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Vernal pools are ephemeral surface water wetlands with unique hydrology, ecology and species composition. Rare and endemic species rely on vernal pool habitat due to specialization traits the species possess ...
Citation Citation
- Title:
- Development of baseline data on Oregon's high desert vernal pools
- Author:
- Wyland, Sara Alice
Vernal pools are ephemeral surface water wetlands with unique hydrology, ecology and species composition. Rare and endemic species rely on vernal pool habitat due to specialization traits the species possess because they are adapted to the extreme conditions. Many vernal pool basins have been topographically and hydrologically altered and are utilized heavily for cattle, which can lead to deleterious effects to vernal pool ecosystems. Little research has been performed on Oregon's high desert vernal pools, impeding proper management and protection. This study was conducted to gather baseline data on the pools over the 2011 and 2012 spring to fall seasons. Water quality analysis was performed to determine if differences exist between natural vernal pools, those that have been altered, and anthropogenic water source alternatives in the region, and to see if water chemistry changes as the pools dry down. Some trends were shown, but the data were highly variable within site classifications. General temporal trends of pools showed increases in temperature, turbidity, conductivity and anions, and decreases in dissolved oxygen and oxidation-reduction potential throughout the seasons. Natural pools displayed opposite temporal trends of turbidity and nitrate than other site types, indicating different chemical functioning. Excavations inside basins where water was only present in the excavation had different water chemistry from excavations where water was overflowing into the natural basin, and from unaltered natural basins, demonstrating impacts of excavated topography. Although some patterns can be recognized, the data was variable and suggest little can be assumed about the water quality status of Oregon’s high desert vernal pools. A GIS and remote sensing method was developed to quantify the change in water surface area in the high desert at various time points by performing supervised classifications of SPOT images. The method was found to be capable of easily deriving surface areas from the SPOT images, with little potential for error. Water surface areas were extracted from ten SPOT images taken from 2010 to 2013. Surface areas were compared to local climate data to assess for determining factors. The temporal resolution of the preliminary analysis was not high enough to determine causation, but results suggest annual precipitation and timing persistence are important factors in water surface areas.
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This study provides an empirical test of the Bockstael-McConnell (1980) household production function (HPF) framework for evaluating wildlife recreation. This is perhaps the first study in which both taste ...
Citation Citation
- Title:
- Measuring benefits of outdoor recreation services : an application of the household production function approach to the Oregon steelhead sport fishery
- Author:
- Strong, Elizabeth J.
This study provides an empirical test of the Bockstael-McConnell (1980) household production function (HPF) framework for evaluating wildlife recreation. This is perhaps the first study in which both taste and technology parameters have been estimated with a theoretical model specification. The results suggest that for steelhead sport fishing in Oregon, the HPF methodology provides a promising recreation valuation technique. Also, some theoretical results are presented which extend Barnett's (1977) formulation of the HPF model to nonconsant returns to scale technologies. Conditions are identified under which it is possible to estimate structural taste and technology parameters. There is also a discussion on welfare analysis in the HPF framework. It is shown that welfare changes can be evaluated in either the input or the commodity markets. Different techniques for calculating two exact welfare measures --- compensating and equivalent variations --- are presented. In the HPF model estimated in this application, anglers are viewed as using market goods and their own time as inputs in the production of fishing experiences from which they derive utility. The two utility-yielding components of a fishing experience are defined as the fishing trip itself and the per trip fish catch. The major difference between this study and most previous studies of angler demand is that fish catch is treated here as an endogenous rather than an exogenous variable. That is, the number of sport-caught fish is found to be influenced by the quantities of inputs used by anglers. An advantage of the HPF framework is that it provides estimates of implicit or hedonic prices for commodities that are not priced on the market. Implicit prices, which are dependent on input prices and technology parameters, may also depend on the quantities of commodities consumed. Empirically specified implicit price functions are presented for both a fishing trip and a sport-caught fish. The results suggest that these implicit prices are not dependent on commodity quantities. The value of a fishing experience is defined in this study as the benefits derived from taking the trip and from catching fish. Estimates of the mean value of a fishing experience are presented in terms of both compensating and equivalent variations. These empirical results may be useful for determining values of fishing sites in Oregon. As is suggested by McConnell (1979) and Bockstael and McConnell (1980), the HPF framework can be used to determine the effects of exogenous quality changes on recreation benefits. In this study selected stream quality variables are included in the fish catch production function. Methods are shown for evaluating the welfare effects of changes in these exogenous quality variables. A model in which one or more quality indices are included could be useful for analyzing welfare effects on anglers of forest management plans or fishery enhancement projects. A problem which arose in this work is that the survey data used for the application was initially gathered for the purpose of apply ing a standard travel cost model. This led to some potentially biased parameter estimates for the HPF model. In spite of some data deficiencies, the results are theoretically plausible; but future research should be directed toward obtaining results for the HPF model which are not subject to these empirical limitations. Also, these results suggest that more research is needed to develop habitat quality indices. Future research efforts should also be directed toward developing multiple-site recreation valuation models. With such models, production relationships can vary across sites and substitution relationships among sites can be examined.
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2253. [Article] A Bayesian approach to marine spatial planning
The marine ecosystem provides a broad spectrum of services for a wide array of user groups. Such broad use of marine resources often results in use conflicts between ecosystem elements and human interests. ...Citation Citation
- Title:
- A Bayesian approach to marine spatial planning
- Author:
- Erhardt, Morgan William
The marine ecosystem provides a broad spectrum of services for a wide array of user groups. Such broad use of marine resources often results in use conflicts between ecosystem elements and human interests. To help mitigate these conflicts, the Bayesian Analysis for Spatial Siting (BASS) tool was developed to incorporate both environmental modeled data and subjective stakeholder input while tracking, maintaining and incorporating uncertainty around both data types. The BASS tool is intended to support marine spatial planning decisions where a wide range of potential user groups have interests that conflict regarding siting decisions. The BASS tool incorporates an initial set of twelve (12) Bayesian Belief Network (BBN) models to provide information on ecosystem and economic services such as habitat suitabilities, device suitabilities and usage pressures which include commercial fishing and recreation activities. These models use environmental data as inputs and return suitability values for potential locations in a near real-time on-request basis. BBN methods were selected for this system to take advantage of their intuitive structural components as well as their ability to incorporate and track uncertainty through the modeling process. Stakeholder input is collected in the system using a subset of software from the AccordTM decision support system by Robust Decisions, Inc. This system uses an intuitive two-step data collection method to quantify stakeholder values regarding the decision making process. In the first step, stakeholder participants rank the decision measures, both modeled and subjective, in terms of importance. This ranking scheme allows for weighting later in the process where exploration of the results may require an understanding of stakeholder priorities. The second step uses another component of the AccordTM system called the Belief Map© to collect the stakeholder’s levels of satisfaction and certainty regarding subjective decision measures. Finally, using an online user interface, the BASS tool allows a decision manager to explore the output data for the sites in terms of both the modeled and stakeholder decision measure values. Additionally, the user can view the tool output with the weighting structure of the various stakeholders to better understand the priorities held by different groups. This method allows a decision manager to better understand the character of a decision and guide its progress toward a resolution that best addresses the most important elements of the process.
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2254. [Article] Distributions and fishery associations of immature short-tailed albatrosses (Phoebastria albatrus) in the North Pacific
Short-tailed albatrosses (Phoebastria albatrus, hereafter "STAL") migrate throughout the North Pacific, overlapping with multiple large scale fisheries. In the Bering Sea, documented bycatch of this species ...Citation Citation
- Title:
- Distributions and fishery associations of immature short-tailed albatrosses (Phoebastria albatrus) in the North Pacific
- Author:
- O'Connor, Amelia J.
Short-tailed albatrosses (Phoebastria albatrus, hereafter "STAL") migrate throughout the North Pacific, overlapping with multiple large scale fisheries. In the Bering Sea, documented bycatch of this species is a focal conservation concern, due to the fact that this species is listed as "endangered" under the U.S. Endangered Species Act. We conducted the first year-round tracking study of immature (≤3 years) STAL, an understudied age class, between 2008 and 2012. We quantify seasonal distributions and fisheries associations. Our findings highlight regional differences in distributions and areas of high vessel associations within the Bering Sea. We examined travel distances across seasons and bird demographics, seasonal ranges of birds, and whether core use areas differed among ages, sexes, or source colonies. Source colonies include Torishima, the main STAL colony, and an anticipated new colony on Mukojima where birds were translocated and hand-reared. Linear mixed models (LMM) were used to evaluate travel distances across temporal and demographic (sex, age, and source colony) variables. Kernel density estimations (KDE) were used to quantify range and core areas. These areas were further analyzed using overlap indices. Regional variations were found in core areas of sexes and age classes. Moreover, STAL in first year of flight have a broader distribution than other ages, which may suggest a period of learning foraging skills or exploratory movements. We also found no concerning differences in year-round distributions between colonies (which included translocated and non-translocated birds), and documented via satellite tracking an initial return to Mukojima by a three year old translocated bird. In the Bering Sea, we examined seasonal distributions and STAL association with Bering Sea/Aleutian Island fisheries. Associations (defined here as STAL locations within 2 hours and 10 kilometers from a vessel setting gear), were quantified spatially and examined with a LMM. STAL-vessel associations occurred year round but predominately during summer and fall months along shelf-break and near canyon habitats. Additionally, the relative abundance of associations with longline vessels vs. other gear types increased from summer to fall, when most STAL bycatch was documented. While greater vessel associations and one bycatch event did occur within STAL high use areas, STAL bycatch during this study period occurred in areas of low longline association. We also did not find variations in fisheries association between translocated and non-translocated STAL.
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2255. [Article] Assessing Policies Promoting Poverty Alleviation and Marine Resource Sustainability in Impoverished Coastal Communities
Full article is forthcoming in African Geographical Review.Citation -
EWEB envisions the development of an investment mechanism that makes payments for ecosystem services (PES) as a way to maintain and improve water quality within the McKenzie River Watershed, Eugene’s sole ...
Citation Citation
- Title:
- EWEB’s Vision: Payments for Ecosystem Services through a Voluntary Incentives Program; An Innovative, Incentive-Based Approach for Preserving Water Quality in the McKenzie River Watershed
- Author:
- Lurie, Sue, Toth, Nancy, Morgenstern, Karl, Duncan, Sally, Fishler, Hillary, Bennett, Drew
EWEB envisions the development of an investment mechanism that makes payments for ecosystem services (PES) as a way to maintain and improve water quality within the McKenzie River Watershed, Eugene’s sole source of drinking water. The public name for this concept is the Voluntary Incentives Program. Under the envisioned Voluntary Incentives Program (VIP), EWEB will provide annual dividend payments to landowners for the valuable services their properties provide including water filtration and purification. These dividends recognize the value of the natural capital provided by these lands and their downstream benefits to the residents of Eugene. A fund with sustainable financing will be established to support the dividend payments and the infrastructure necessary to operate the Voluntary Incentives Program. Financing will come from a variety of sources but could be initially endowed through existing water funds (under existing rate structure) or another utility funding mechanism. Additional possible financing sources other than EWEB include corporations, a voter approved bond measure, development impact fees, and state and federal mitigation programs. EWEB will establish a stewardship boundary identifying riparian forests and floodplains that are eligible to enroll in the VIP. Participation is open to private landowners, local governments, and non-profit organizations that own land within the designated boundary. Based on EWEB’s preliminary analysis, an estimated 6,500 acres of riparian and floodplain areas along the McKenzie and major tributaries are eligible to enroll. Land within the stewardship boundary will need to meet a threshold in order to receive payments. This threshold will be determined by adapting existing riparian forest and wetland habitat standards and definitions from NRCS, USFS, Defenders of Wildlife and other entities to establish the criteria for participation in the VIP. Appropriate infrastructure is essential to implement and run the incentives program: critical tasks include managing the fund, making payments to VIP participants, assessing the quality of land enrolled, negotiating agreements, monitoring properties and verifying compliance, and educating and communicating with the community. The VIP will rely upon a coalition of existing organizations, which will form a watershed investment district (WID), to provide this critical infrastructure, without which successful implementation of the VIP is highly unlikely.
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2257. [Article] Vascular Plant Inventory for Lewis and Clark National Historical Park - Public Version
Natural Resource Technical Report NPS/LEWI/NRTR—2012/603.N Research was conducted under permit # FOCL-2009-SCI-0002 for study number FOCL-00005Citation Citation
- Title:
- Vascular Plant Inventory for Lewis and Clark National Historical Park - Public Version
- Author:
- Kagan, Jimmy, Institute for Natural Resources, Wise, Lindsey Koepke, The Oregon Biodiversity Information Center
Natural Resource Technical Report NPS/LEWI/NRTR—2012/603.N Research was conducted under permit # FOCL-2009-SCI-0002 for study number FOCL-00005
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2258. [Article] Dispersal strength determines meta-community structure in a dendritic riverine network
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by John Wiley & Sons, Ltd., and can be found at: http://onlinelibrary.wiley.com/jo...Citation Citation
- Title:
- Dispersal strength determines meta-community structure in a dendritic riverine network
- Author:
- Lytle, David A., Olden, Julian D., Phillipsen, Ivan, Bogan, Michael T., Schriever, Tiffany A., Boersma, Kate S., Cañedo-Argüelles, Miguel
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by John Wiley & Sons, Ltd., and can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291365-2699
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2259. [Article] Comparison of Contemporary and Heritage Fish Consumption Rates in the Columbia River Basin
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/10745Citation Citation
- Title:
- Comparison of Contemporary and Heritage Fish Consumption Rates in the Columbia River Basin
- Author:
- Harper, Barbara L., Walker, Deward E., Jr.
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/10745
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2260. [Article] The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2011
From 6 April – 19 September 2011 we monitored the distribution, abundance and productivity of the federally Threatened Western Snowy Plover (Charadrius nivosus nivosus) along the Oregon coast. From north ...Citation Citation
- Title:
- The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2011
- Author:
- Institute for Natural Resources, Castelein, Kathleen A., Gaines, Eleanor P., Lauten, David J., Farrar, J. Daniel, Kotaich, Adam A.
From 6 April – 19 September 2011 we monitored the distribution, abundance and productivity of the federally Threatened Western Snowy Plover (Charadrius nivosus nivosus) along the Oregon coast. From north to south, we surveyed and monitored plover activity at Sutton Beach, Siltcoos River estuary, the Dunes Overlook, North Tahkenitch Creek, Tenmile Creek, Coos Bay North Spit, Bandon Beach, New River, and Floras Lake. Our objectives for the Oregon coastal population in 2011 were to: 1) estimate the size of the adult Snowy Plover population, 2) locate plover nests, 3) continue use of mini-exclosures(MEs) to protect nests from predators when and where needed, 4) determine nest success, 5) determine fledging success, 6) monitor brood movements, 7) collect general observational data about predators, and 8) evaluate the effectiveness of predator management. We observed an estimated 247-253 adult Snowy Plovers; a minimum of 214 individuals were known to have nested. The adult plover population was the highest estimate recorded since monitoring began in 1990. We monitored 289 nests in 2011, the highest number of nests since monitoring began in 1990. Overall apparent nest success was 50%. Exclosed nests (n = 48) had a 71% apparent nest success rate, and unexclosed nests (n = 241) had a 48% apparent nest success rate. Nest failures were attributed to unknown depredation (22%), corvid depredation (20%), unknown cause (18%), one-egg nests (16%), abandonment (15%), wind/weather (3%), mammalian depredation (2%), adult plover depredation (2%), infertility (1%), and rodent depredation (1%). We monitored 148 broods, including four from unknown nests, and documented a minimum of 168 fledglings. Overall brood success was 71%, fledging success was 46%, and 1.57 fledglings per male were produced. Continued predator management, habitat improvement and maintenance, and management of recreational activities at all sites are recommended to achieve recovery goals.
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2261. [Article] The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2011
From 6 April – 19 September 2011 we monitored the distribution, abundance and productivity of the federally Threatened Western Snowy Plover (Charadrius nivosus nivosus) along the Oregon coast. From north ...Citation Citation
- Title:
- The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2011
- Author:
- Institute for Natural Resources, Kotaich, Adam A., Portland State University/INR, Farrar, J. Daniel, The Oregon Biodiversity Information Center, Castelein, Kathleen A, Gaines, Eleanor P., Lauten, David J.
From 6 April – 19 September 2011 we monitored the distribution, abundance and productivity of the federally Threatened Western Snowy Plover (Charadrius nivosus nivosus) along the Oregon coast. From north to south, we surveyed and monitored plover activity at Sutton Beach, Siltcoos River estuary, the Dunes Overlook, North Tahkenitch Creek, Tenmile Creek, Coos Bay North Spit, Bandon Beach, New River, and Floras Lake. Our objectives for the Oregon coastal population in 2011 were to: 1) estimate the size of the adult Snowy Plover population, 2) locate plover nests, 3) continue use of mini-exclosures (MEs) to protect nests from predators when and where needed, 4) determine nest success, 5) determine fledging success, 6) monitor brood movements, 7) collect general observational data about predators, and 8) evaluate the effectiveness of predator management. We observed an estimated 247-253 adult Snowy Plovers; a minimum of 214 individuals were known to have nested. The adult plover population was the highest estimate recorded since monitoring began in 1990. We monitored 289 nests in 2011, the highest number of nests since monitoring began in 1990. Overall apparent nest success was 50%. Exclosed nests (n = 48) had a 71% apparent nest success rate, and unexclosed nests (n = 241) had a 48% apparent nest success rate. Nest failures were attributed to unknown depredation (22%), corvid depredation (20%), unknown cause (18%), one-egg nests (16%), abandonment (15%), wind/weather (3%), mammalian depredation (2%), adult plover depredation (2%), infertility (1%), and rodent depredation (1%). We monitored 148 broods, including four from unknown nests, and documented a minimum of 168 fledglings. Overall brood success was 71%, fledging success was 46%, and 1.57 fledglings per male were produced. Continued predator management, habitat improvement and maintenance, and management of recreational activities at all sites are recommended to achieve recovery goals.
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2262. [Article] The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2010
From 8 April – 27 September 2010 we monitored the distribution, abundance and productivity of the federally Threatened Western Snowy Plover (Charadrius alexandrinus nivosus) along the Oregon coast. From ...Citation Citation
- Title:
- The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2010
- Author:
- Institute for Natural Resources, Farrar, Daniel, Castelein, Kathleen A., Kotaich, Adam A., Lauten, David J., Gaines, Eleanor P.
From 8 April – 27 September 2010 we monitored the distribution, abundance and productivity of the federally Threatened Western Snowy Plover (Charadrius alexandrinus nivosus) along the Oregon coast. From north to south, we surveyed and monitored plover activity at Sutton Beach, Siltcoos River estuary, the Dunes Overlook, North Tahkenitch Creek, Tenmile Creek, Coos Bay North Spit, Bandon Beach, New River, and Floras Lake. Our objectives for the Oregon coastal population in 2010 were to: 1) estimate the size of the adult Snowy Plover population, 2) locate plover nests, 3) continue selective use of mini-exclosures (MEs) to protect nests from predators and evaluate whether exclosure use can be reduced, 4) determine nest success, 5) determine fledging success, 6) monitor brood movements, 7) collect general observational information about predators, and 8) evaluate the effectiveness of predator management. We observed an estimated 232-236 adult Snowy Plovers; a minimum of 175 individuals was known to have nested. The adult plover population was the highest estimate recorded since monitoring began in 1990. We monitored 261 nests in 2010, the highest number of nests since monitoring began in 1990. Overall Mayfield nest success was 25%. Exclosed nests (n = 67) had a 72% apparent nest success rate, and unexclosed nests (n = 194) had a 23% apparent nest success rate. Nest failures were attributed to unknown depredation (24%), unknown cause (17%), one-egg nests (15%), rodent depredation (14%), abandonment (12%), wind/weather (5%), corvid depredation (5%), mammalian depredation (4%), wave overwash (2%), infertility (2%), and adult depredation (1%). We monitored 94 broods, including two from unknown nests, and documented a minimum of 80 fledglings. Overall brood success was 55%, fledging success was 33%, and 0.90 fledglings per male were produced. Continued predator management, habitat improvement and maintenance, and management of recreational activities at all sites are recommended to achieve recovery goals.
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2263. [Article] Control of Lepidium latifolium and restoration of native grasses
Lepidium latifolium L. (perennial pepperweed, LEPLA) is an exotic invader throughout western North America. At Malheur National Wildlife Refuge (MNWR) in southeast Oregon, it has invaded about 10% of meadow ...Citation Citation
- Title:
- Control of Lepidium latifolium and restoration of native grasses
- Author:
- Laws, Margaret S.
Lepidium latifolium L. (perennial pepperweed, LEPLA) is an exotic invader throughout western North America. At Malheur National Wildlife Refuge (MNWR) in southeast Oregon, it has invaded about 10% of meadow habitats that are important for wildlife. This study's objective was to determine the most effective and least environmentally harmful treatment to control this weed and restore native vegetation using integrated pest management techniques. During summer 1995, nine 0.24-ha plots in three meadows infested with L. latifolium at MNWR were randomly assigned to a treatment with metsulfuron methyl herbicide, chlorsulfuron herbicide, disking, burning, herbicide (metsulfuron methyl or chlorsulfuron) then disking, herbicide (metsulfuron methyl or chlorsulfuron) then burning, or untreated. Changes in L. latifolium ramet densities and basal cover of vegetation, litter, and bare soil were evaluated in 1996 and 1997. Sheep grazing was evaluated as a treatment for reduction in flower production along roadsides and levees during summer 1997. Revegetation treatments of seeding, transplanting or natural (untreated) revegetation were attempted at plots treated with chlorsulfuron, disking, chlorsulfuron then disking, and at untreated plots from October 1996 through September 1997. Chlorsulfuron was the most effective control treatment with greater than 97% reduction in L. latifolium ramet densities two years after treatment. Metsulfuron methyl was an effective control (greater than 93% reduction) for one year. Disking was ineffective. Burning was ineffective at the one site where sufficient fine fuels existed to carry fire. Herbicide treatments were associated with increased grass and reduced forb cover. Disking was associated with reduced grass and litter cover. Disking combined with either herbicide treatment was associated with reductions in all plant cover (49 to 100%), increased bare ground, and invasion by other weedy species such as Cirsium arvense (L.) Scop. (Canada thistle, CIRAR) and Bromus tectorum L. (cheatgrass, BROTE). Ungrazed L. latifolium averaged 4513 flowers per ramet. Sheep grazing reduced L. latifolium flower production by at least 98%. Revegetation treatments were unnecessary in sites treated with chlorsulfuron and were ineffective at all treatment sites.
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2264. [Article] Origins of the old-growth forest conflict (1971-1989) : a new model for resource allocation
The old-growth forest conflict is part of the evolving debate over how to use the federal public lands. This study documents the origins and development of the old-growth issue through 1989. The controversy ...Citation Citation
- Title:
- Origins of the old-growth forest conflict (1971-1989) : a new model for resource allocation
- Author:
- Wilson, Mark Shelton
The old-growth forest conflict is part of the evolving debate over how to use the federal public lands. This study documents the origins and development of the old-growth issue through 1989. The controversy began in the early 1970s when scientists initiated studies of old-growth forests and northern spotted owls, and the land stewardship policies of the U.S. Forest Service were challenged by both preservation and timber industry interests. This thesis identifies the participants in the old-growth issue along with their views concerning the physical attributes of old-growth forests, values associated with these forests, and the appropriate use of old-growth forests. The timber industry viewed old-growth as a raw material for mills while preservationists primarily valued old-growth as wildlife habitat. The conflict was complicated by the use of different parameters for definitions of old-growth, land ownership, land-use, geographic area, forest type and year of data collection. All sides in the issue tended to view the federal resource management agencies, particularly the Forest Service, as biased or incompetent. Preservation and timber industry interests, agency personnel, and federal judges felt only Congress could provide a solution to the conflict. The various views of old-growth affected behaviors that influenced policy development to advance different ideas of appropriate old-growth use. Preservationists were very effective at using administrative appeals and lawsuits of agency decisions to create a regional timber supply crisis in 1989 and move the issue from a regional level to the national level. The increased level of intensity of the conflict forced both preservation and timber interests to form new coalitions to advance their agendas through their supporters in Congress. Based on the interactions of old-growth issue participants within and among the four elements of competing interest groups, congressional committees and subcommittees, the federal courts, and the federal natural resource management agencies, a new model of policy development "the wobbly diamond" was designed to analyze issue participants' behaviors and the policy development process. Although there was no explicit policy shift at the end of 1989 when Congress passed legislation relevant to the conflict, the result of the overall policy process during 1989 was a dramatic decrease in the amount of federal timber sold and a situation created wherein Congress would be involved in the issue for many years to come.
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Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, ...
Citation Citation
- Title:
- The influence of climate change and restoration on stream temperature
- Author:
- Diabat, Mousa
Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, and channel structure directly influence stream temperature. Numerous studies indicate that increased average air temperature during the past century has led to stream warming across the world. The trend of stream warming was also present in spring-fed watersheds, where summer flow has decreased. In addition, anthropogenic practices that alter the natural landscape and channel structure, such as forest management, agriculture, and mining contributed to stream warming. For example, deforested and unshaded stream reaches or dredged channels were warmer than shaded reaches and meandering streams. Stream temperatures in North American lotic habitats are of a specific concern due to their significant economic, cultural, and ecological value. With climate projections indicating that air temperature will only continue to rise throughout the 21st century, cold- or cool-water organisms, especially fishes, will be affected. Therefore, there is a strong need to better understand the impacts of changing climate, riparian landscape, and channel structure on a stream's heat budget. This may assist in restoring the historic thermal regime in impacted sites and mitigating the impacts of future climate change. This study looks into the relative influences of the different factors on a stream's heat budget with three manuscripts: one on stream temperature response to diel timing of air warming, one on stream temperature response to changes in air temperature, flow, and riparian vegetation, and one on stream temperature response to air warming and channel reconstruction. I used the software Heat Source version 8.05 to simulate stream temperature for all three analyses along the Middle Fork John Day River, Oregon USA. Two of the manuscripts were applied to an upper 37 km section of the Middle Fork John Day River (presented in chapter 2 and 3), where the third manuscript was applied to a 1.5-km section. The sensitivity analysis of stream temperature response to diel timing of air warming (Chapter 2: Diel Timing of Warmer Air under Climate Change Affects Magnitude, Timing, and Duration of Stream Temperature Change) was based on scenarios representing uniform air warming over the diel period, daytime warming, and nighttime warming. Uniform warming of air temperature is a simple representation of increases in the average daily or monthly temperatures generated by the 'delta method'. The delta method relies on adding a constant value to the air temperature time-series data. This constant value is the difference (delta) between base case average air temperatures and the projected one. Scenarios of daytime or nighttime warming represent conditions under which most of the warming of the air occurs during the daytime or the nighttime, respectively. I simulated the stream temperature response to warmer air conditions of +2 °C and +4 °C in daily average for all three cases of air warming conditions. The three cases of different diel distributions of air warming generated 7-day average daily maximum stream temperature (7DADM) increases of approximately +1.8 °C ± 0.1 °C at the downstream end of the study section relative to the base case. In most parts of the reach, the three distributions of air warming generated different ranges of stream temperatures, different 7DADM values, different durations of stream temperature changes, and different average daily temperatures. Changes of stream temperature were out of phase with imposed changes of air temperature. Therefore, nighttime warming of air temperatures would cause the greatest increase in maximum daily stream temperature, which typically occurs during the daytime. The sensitivity analysis of the relative influences of changes in air temperature, stream flow, and riparian vegetation on stream temperature (Chapter 3: Assessing Stream Temperature Response to Cumulative Influence of Changing Air Temperature, Flow, and Riparian Vegetation). This study summarized stream temperature simulation in 36 scenarios representing possible manifestations of 21st century climate conditions and land management strategies. In addition to existing conditions (base case) of flow, air temperature, and riparian vegetation, scenarios consisted of: two air temperature increases of 2 °C and 4 °C, two stream flow variations of +30% and -30%, three spatially uniform riparian vegetation conditions that create averages of effective shade 7%, 34%, and 79%, in addition to 14% for base case conditions. Results suggest that variation in riparian vegetation was the dominant factor influencing stream temperature because it regulates incoming shortwave radiation, the largest heat input to the stream, while variation in stream flow has a negligible influence. Results indicated that increasing the effective shade along the study section, particularly in the currently unshaded sections, could mitigate the influence of increasing air temperature, and would reduce stream temperature maxima below current values even under future climate conditions of warmer air. With the small influence it had, increasing stream flow reduced the 7DADM under low shade conditions. However, increasing stream flow showed counterintuitive results as it contributed to increasing stream temperature maxima when the stream was heavily shaded. The applied study examined the stream temperature response to restoration practices and their potential to mitigate the influence of warmer air conditions (Chapter 4: Estimating Stream Temperature Response to Restoring Channel and Riparian Vegetation and the Potential to Mitigate Warmer Air Conditions). This study focused on a 1.5 km section along the upper part of the Middle Fork John Day River that was modified due to past anthropogenic activities of mining for gold and timber harvest. Currently, the riparian vegetation of the study site is mostly shrubs and stands of short trees. Restoration designs call for the restoration of both the channel structure and replanting the riparian vegetation. Simulation results showed that the 7DADM was higher in the restored channel than the existing channel with both conditions of low and high effective shade conditions. However, a combined restoration practice of channel reconstruction and medium effective shade conditions reduced stream temperature maxima more than restoring riparian vegetation alone. In addition, results showed that restoring riparian vegetation was sufficient to mitigate the influence of warmer air on stream temperature, while restoring the channel alone is not. Heat budget analysis showed that heat accumulation during the daytime increased in the restored channel, which was longer, narrower, and deeper than the existing channel. It is important to emphasize that stream temperature is one of many goals that restoration activities aim to improve. Furthermore, differences in 7DADM among the different scenarios of restoration are negligible. Such small differences could hardly be measure. While this study examined a short section of 1.5 km, longer stream sections may increase the differences in 7DADM. Primary conclusions of this study are: 1) daily maxima of stream temperature will increase in response to increased air temperature regardless of the distribution of air warming during the diel cycle; 2) nighttime air warming caused a greater increase in stream temperature maximum than daytime warming; 3) riparian vegetation was the dominant factor on stream's heat budget, more than air temperature or stream flow; 4) restoring riparian vegetation mitigated the influence of warmer air; 5) restoring channel structure alone was not sufficient to lower temperature maxima; and 6) restoration project was most successful in improving degraded stream temperature when combined with channel reconstruction and improved riparian shade.
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2266. [Article] The Educational values of trees and forests
Authors' affiliation/contact: Department of Environment and Society, Utah State University, Logan, UT 84322-5215 (Terry.Sharik@usu.edu)Citation -
The California brown pelican (Pelecanus occidentalis californicus) is listed as an endangered species under the U.S. Endangered Species Act. The Recovery Plan for this subspecies outlines the need to "Assure ...
Citation Citation
- Title:
- Disturbance and roosting ecology of California brown pelicans (Pelecanus occidentalis californicus) on East Sand Island in the Columbia River Estuary
- Author:
- Wright, Sadie K.
The California brown pelican (Pelecanus occidentalis californicus) is listed as an endangered species under the U.S. Endangered Species Act. The Recovery Plan for this subspecies outlines the need to "Assure long-term protection of adequate food supplies and essential. . .roosting. . . habitat throughout the range." I investigated the effects of disturbance to California brown pelicans roosting on East Sand Island in the Columbia River estuary to determine if disturbances were degrading the quality of the roost site. During the summers of 2001 and 2002, I examined potential differences in pelican numbers, distribution, and behavior on East Sand Island before and after disturbances caused by research activity, non-research anthropogenic factors, and natural factors. East Sand Island was the site of the largest known post-breeding roost for California brown pelicans, with peak numbers of 10,852 counted on the island in September 2002. Year, date, and tide height accounted for over 90% of the variation in pelican numbers on East Sand Island. Research activity on the island was the only category of disturbance that had a detectable effect on the total number of pelicans roosting on East Sand Island. In 2001 the magnitude of research disturbance had a marginally significant negative association with total pelican numbers (P = 0.09), but in 2002 there was no significant association (P = 0.31). Research activity and non-research anthropogenic disturbance were negatively associated with pelican numbers in localized parts of the roost near the west end of East Sand Island, where these disturbance factors were most prevalent. I measured the effects of disturbance on the behavior of roosting California brown pelicans by collecting time-activity budget data for pelicans roosting in a study plot that encompassed 136 m of shoreline. All three categories of disturbance affected the time-activity budgets of roosting pelicans, as indicated by changes during the half hour following a disturbance: the proportion of resting pelicans decreased and the proportion of attentive pelicans increased. Disturbances caused by research activity on the island appeared to have a greater and longer lasting impact on time-activity budgets of pelicans roosting in the study plot, compared to non-research anthropogenic disturbances (i.e., watercraft) or natural disturbances (mostly by bald eagle fly-bys). Although natural disturbances did not appear to have as pronounced an effect as did anthropogenic disturbances on the numbers, distribution, and behavior of pelicans roosting on East Sand Island, natural disturbances may gradually deter pelicans from using the island as a roost. Bald eagles caused more pelicans to flush from East Sand Island than all other types of disturbance combined. Bald eagle disturbance rates (pelicans flushed/hour) steadily increased from 2001 to 2003. It would be useful to monitor use of East Sand Island by nomadic sub-adult bald eagles, which use the island more than breeding adults, to determine trends. In addition, the island should be carefully monitored to detect any large mammalian predators that access the island and all large predators should be removed immediately to prevent abandonment of the island by roosting and nesting colonial waterbirds. East Sand Island is closed to the public to protect breeding and roosting waterbirds from unrestricted human disturbance. Recreational boaters should be educated that the island is closed during the seasons when waterbirds are aggregated on the island so they understand and are more likely to comply with the restrictions. Although researchers took several precautions to minimize disturbance to brown pelicans, as stipulated by a protocol approved by the U.S. Fish and Wildlife Service (USFWS), there was still an apparent negative effect of this source of human activity on pelican numbers and behavior. Unrestricted access by researchers would certainly have a larger impact than observed during this study, so restrictions should continue. Researchers should only access beaches with low pelican densities (Camp to Dike, North and East Beaches; unless otherwise specifically permitted by USFWS), access the west end bird blinds only within 2 hours of low tide, and postpone or cancel any research activities that could potentially flush greater than 15% of the pelicans roosting on East Sand Island.
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2268. [Article] The ecology of wild turkey (Meleagris gallopavo) foraging in Pacific Northwest ecosystems
Wild turkeys (Meleagris gallopavo) were first successfully introduced into Oregon and Washington in the 1960s; the population has grown in size and expanded in distribution to a point where it provides ...Citation Citation
- Title:
- The ecology of wild turkey (Meleagris gallopavo) foraging in Pacific Northwest ecosystems
- Author:
- Evans-Peters, Sara Tondee
Wild turkeys (Meleagris gallopavo) were first successfully introduced into Oregon and Washington in the 1960s; the population has grown in size and expanded in distribution to a point where it provides an important recreational hunting opportunity in both states that generates significant funds for habitat conservation and contributes financially to local economies. Wild turkeys are not native to Oregon or Washington leading some to question if turkeys should be actively managed as a game bird. While no detrimental effects of turkeys have been documented in either state, there has been virtually no research on the biology and ecology of turkeys in Oregon and Washington to contribute information that aids in managing the species and informing the debate about managing for the persistence of a non-native species. In this thesis, I quantify the diet of turkeys in Oregon and Washington and determine if wild turkeys are endozoochorously dispersing the seeds of plants they consume. Contributing information about the basic biology of turkeys could aid management and help contribute to a mechanistic understanding of how turkeys might help shape ecosystem structure and function. I characterized the diet of wild turkeys in Oregon and Washington by examining the crops of hunter harvested and collected turkeys (n = 536) during three time periods (fall-winter, spring and summer) from four geographic regions during 2009-2011. I compared diet composition among regions and between seasons at both a broad categorical level (i.e., fruits, leaves, flowers, invertebrates and underground plant parts) and at the level of individual taxa. Based on previous research, I predicted that consumption of leaves, flowers, and invertebrates would be higher in spring and consumption of fruits would be highest in fall in all regions, but specific taxa that comprised each broad category of food would vary among regions. I detected 123 plant and 35 invertebrate taxa in turkey crops. Consistent with my prediction, wild turkeys consumed significantly more fruits in fall/winter and more leaves and flowers in the spring; contrary to my prediction, invertebrate consumption was higher in fall-winter for three of the four regions. Grasses (Poaceae) were the most common leafy material consumed in all regions during both fall-winter and spring and the most common fruits consumed in all regions during both seasons except in one region, in spring, where oak acorns (Quercus sp.) dominated the diet. Within the grass family, wheat (Triticum sp.) was the most abundant seed in all regions in fall-winter and the most abundant seed in 2 regions in spring while corn (Zea sp.) was the most abundant seed in the remaining regions in spring. The only other plant families that comprised >5% of aggregate percent dry mass within regions (all food categories combined) included Rosaceae, Pinaceae, Fagaceae and Asteraceae in fall- winter and Fabaceae, Fagaceae, Asteraceae, Pinaceae, and Ranunculaceae in spring. Grasshoppers (Acrididae) were the most abundant invertebrate taxa in fall-winter while snails (Gastropoda) were the most abundant invertebrate in spring. Aggregate percent dry mass of food items differed by season for each region and differed among regions when analyzed by season. Within each region, numerous taxa were unique and indicative of season (range: 2-18) but fewer taxa were indicative of region (range: 0-9) indicating there was more variation in diet between seasons than among regions. To examine dispersal capabilities, we recovered seeds contained within wild turkey feces (30 feces/sample, n = 50 samples) during the fall-winter between 2009 and 2011. Twenty-two taxa of seeds were found intact and 9 of those were viable (41%) based on tetrazolium testing. Viability ranged from 2-70%, Fabaceae sp. (pea family) had the highest viability (70%) followed by Toxicodendron sp. (poison oak-ivy, 24.5%) and Symphoricarpos sp. (snowberry, 11.6%); the viability of the remaining 6 taxa was below 10%. The majority of seed taxa present in wild turkey diet in Oregon and Washington were not represented in fecal samples indicating turkeys destroy the majority of taxa consumed during the digestive process. Though wild turkeys appear to be primarily a seed predator, I found they are successfully dispersing 14.5% of the seed taxa identified in the diet. Most taxa identified in the diet and fecal samples were identified to family and there are natives and non-native species within those families. My results do not conclusively document any direct or indirect impacts of turkeys on native plants or wildlife, but do provide a baseline for considering impacts and future information needs.
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2269. [Article] Taxonomy and distribution of the leaf-hopper genus Aphrodes Curtis (Homoptera:Cicadellidae) in North America
The subfamily Aphrodinae is represented in the Nearctic Region by eight species contained in a single tribe, Aphrodini, and genus Aphrodes. The external and internal morphology, biology and ecology of ...Citation Citation
- Title:
- Taxonomy and distribution of the leaf-hopper genus Aphrodes Curtis (Homoptera:Cicadellidae) in North America
- Author:
- Klein, Terry Allen
The subfamily Aphrodinae is represented in the Nearctic Region by eight species contained in a single tribe, Aphrodini, and genus Aphrodes. The external and internal morphology, biology and ecology of the Nearctic members of the genus Aphrodes were investigated. Distributional evidence indicates that six of the eight species, belonging to the subgenera Aphrodes and Anoscopus, have been introduced from the Palearctic Region, presumably via maritime shipping. These six species occur either within the West Coast and adjacent land area or the East Coast and Great Lakes region and adjacent land areas, or both. The other two species, belonging to the subgenus Stroggylocephalus, are believed to be indigenous to North America and are not known to occur elsewhere. These two species have been recorded from numerous North American localities between 35°N and 58°N latitude. The irregular distribution of Nearctic members of the subgenus Stroggylocephalus indicates that these species now exist as relict populations. Two species of the subgenus Stroggylocephalus are recorded from Europe with one, agrestis, reported as occurring in North America. However, records of agrestis in North America were not verified, and prior records are believed to be erroneous. A single female of the subgenus Stroggylocephalus from Kentucky apparently represents a new species, the third known from North America. The Nearctic species of Aphrodes are here assigned to three subgenera: Aphrodes s. s., Anoscopus and Stroggylocephalus. Species differentiation is based primarily on features of the male genitalia. The structure, length, and number of retrorse spines of the aedeagus is unique for each species. The structure of the pygofer hook and style, the shape and setation of the genital plate and the absence or presence of a secondary papilliform structure adjacent to the pygofer hook were found to be useful in discriminating between some species and species groups. Morphological differentiation of females of some species is nearly impossible. The number of dentations on valve II of the ovipositor was found to be unreliable for discriminating species or species groups, in contrast to Readio's findings (1922). Color and color pattern of the forewing, face and crown in males and some females were frequently found to be useful for recognition of some species and species groups even though considerable amounts of variation occur within a species. Wing venation is variable; the venation of the two forewings of the same insect are often different. However, the length of the forewing was found to be a reliable character for distinguishing members of Aphrodes s. s. and Stroggylocephalus from Anoscopus. Crown L:W ratios of the females are usually smaller than the males and ratios of both sexes are unreliable for species differentiation because of the amount of infras pecific variation. Evidence regarding anatomy of the reproductive organs of species of Aphrodes, studied for the purpose of comparison with representatives of other genera and subfamilies of leafhoppers, although limited in scope, provides information useful for species differentiation in sexually mature males. The structure of the reproductive tracts supports the conclusion that the species studied belong to a single genus Aphrodes, or at most to two genera, Aphrodes and Stroggylocephalus. The Nearctic species of the genus Aphrodes are characterized through illustrations, verbal descriptions and a diagnostic key. Infraspecific variation consists primarily of differences in color, color pattern and size. The male genitalia are relatively uniform with some minor differences occurring in the length and rugosity of the styles, rugosity and crenulations on the lateral margin and apex of the pygofer hooks, and length and position of the retrorse spines of the aedeagus. The nymphal instars of three species--A. bicinctus, albifrons and serratulae--are described. The color and color pattern were found to be distinct for each of these species from the second ins tar to the final molt. Field and laboratory studies demonstrate that at least some of the species of Aphrodes are polyphagous. Two species, serratulae and albifrons, appear to prefer grasses, but will also feed on clovers. Those Nearctic species of Aphrodes that have been studied with reference to habitat preference are found in such places as near the base of plants, in soil surface litter, and under or around rocks and boards. Members of Aphrodes s. s. and Anoscopus are univoltine, with a few females surviving the winter. Adults of Stroggylocephalus have been recorded during nearly every month which suggests a polyvoltine life cycle.
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Understanding the movement behavior and foraging strategies of individuals across multiple spatial and temporal scales is essential not only for understanding the biological requirements of individuals ...
Citation Citation
- Title:
- Foraging ecology, diving behavior, and migration patterns of harbor seals (Phoca vitulina richardii) from a glacial fjord in Alaska in relation to prey availability and oceanographic features
- Author:
- Womble, Jamie Neil
Understanding the movement behavior and foraging strategies of individuals across multiple spatial and temporal scales is essential not only for understanding the biological requirements of individuals but also for linking individual strategies to population level effects. Glacial fjords scattered throughout south-central and southeastern Alaska host some of the largest seasonal aggregations of harbor seals (Phoca vitulina richardii) in the world, and an estimated 15% of the harbor seal population in Alaska is found seasonally at these glacial ice sites. Over the last two decades, the number of harbor seals has declined at two of the primary glacial fjords, in Aialik Bay in south-central Alaska and in Glacier Bay in southeastern Alaska, thus raising concerns regarding the viability of seal populations in glacial fjord environments. From 2004-2009, the foraging ecology, diving behavior, and migration patterns of harbor seals from Glacier Bay National Park, Alaska were examined in relation to prey availability and oceanographic features in Glacier Bay and the surrounding regions of southeastern Alaska. Time-depth recorders, very high frequency transmitters, and satellite-linked transmitters were used to quantify the vertical and horizontal movement patterns of harbor seals in the marine environment. Specifically, (1) I characterized the diving behavior, foraging areas, and foraging strategies of female harbor seals from terrestrial and glacial ice sites relative to prey availability during the breeding season (May-June) in Glacier Bay, (2) I quantified the intra-population variation in at-sea post-breeding season (September-April) distribution and movement patterns of female harbor seals in relation to oceanographic features, (3) I quantified the post-breeding season migration patterns of female harbor seals relative to the boundaries of the marine protected area of Glacier Bay National Park, and (4) I characterized the use of the continental shelf region of the eastern Gulf of Alaska by female harbor seals from Glacier Bay, both as a foraging area and as a migratory corridor in relation to oceanographic features. During the breeding season, there was a substantial degree of intra-population variation in the diving behavior and foraging areas of juvenile and adult female seals from glacial ice and terrestrial sites in Glacier Bay. The presence of multiple diving strategies suggests that differences in the relative density and depth of prey fields in glacial ice and terrestrial habitats in addition to seal age and reproductive status may influence diving and foraging behavior of harbor seals. During the post-breeding season, juvenile and adult female harbor seals ranged extensively beyond the boundaries of the marine protected area of Glacier Bay National Park, throughout the northern inshore waters of southeastern Alaska and the continental shelf region of the eastern Gulf of Alaska between Cross Sound and Prince William Sound, Alaska (up to 900 kilometers away). Seals exhibited a relatively high degree of intra-population variation in their at-sea post-breeding season distribution patterns that may be a function of extrinsic factors such as oceanographic characteristics, which can influence prey availability as well as intrinsic factors including previous experience with foraging areas and seal condition and age. Use of the continental shelf region of the eastern Gulf of Alaska by harbor seals as a foraging area may be due to enhanced biological productivity which may be associated with ephemeral hydrographic and/or static bathymetric features. Despite extensive migrations of seals from Glacier Bay during the post-breeding season, there was a high degree of inter-annual site fidelity of seals to Glacier Bay the following breeding season after seals were captured.
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2271. [Article] Stable, low-growing plant communities in the western Cascade Mountains : species processes and their implications for rights-of-way management
The processes that lead to stable, low-growing plant communities and the characteristics of the species that form them are of great interest to rights-of-way (ROW) managers and others wishing to better ...Citation Citation
- Title:
- Stable, low-growing plant communities in the western Cascade Mountains : species processes and their implications for rights-of-way management
- Author:
- Nesmith, Jonathan C. B.
The processes that lead to stable, low-growing plant communities and the characteristics of the species that form them are of great interest to rights-of-way (ROW) managers and others wishing to better understand plant community resistance to tree invasion on managed landscapes. The use of stable, low-growing plant communities as a mechanism to control tree invasion on ROWs has been widely acknowledged, but little is known about what plant characteristics lead to stable communities or how different treatment methods affect low-growing communities in the Pacific Northwest. The goal of this study was to assess the resistance of stable, low-growing communities to tree invasion on ROW in the Pacific Northwest and to identify common characteristics among the species in these communities that contributed to the formation of stable communities. To address this goal, we investigated 1) the abilities of different species within the low-growing component of the ROW communities to resist invasion by trees and to fill newly created gaps caused by disturbance, 2) the growth patterns and potential for vegetative reproduction of trailing blackberry (Rubus ursinus Cham and Schlecht) and creeping snowberry (Symphoricarpos mollis Nutt.) to understand how different clonal propagation patterns affect spread into unoccupied space and infilling of currently colonized areas, and 3) the effectiveness of several common vegetation control methods for reducing the density of undesirable species and promoting the development of lowgrowing plant communities on ROW. These factors are important processes that determine the stability of a low-growing plant community. This project was conducted at three sites in the western foothills of the Cascade Mountains of Oregon and Washington. Species composition and abundance was measured in roughly 330 2x2 m plots at each site prior to the application of three different treatments aimed at removing tall-growing target species. The plots were measured again two years later to assess changes in species cover. The growth pattern and architecture of trailing blackberry and creeping snowberry was also investigated through the careful excavation of both individual plants and lxi m plots centered in dense thickets of each species. The various treatments used in this study resulted in an average increase in nontarget cover of 65% from 2000 to 2002 while reducing tall target cover by an average of 53%. No difference was found in the change in average nontarget cover or tall target cover among treatments. The effectiveness of the various treatments in reducing target cover varied significantly based on the type of target species being treated. There were no strong differences in resistance among the common lowgrowing species to invasion by tall target species. The range in increase in tall target cover in plots dominated by low-growing species was highly skewed, as tall target cover increased very little in many plots and by as much as 28% in a very few. In the first two years following disturbance, shrubs capable of rapid horizontal expansion through vegetative reproduction, such as trailing blackberry and bracken fern (Pteridium aquilinum), were most successful filling gaps. Their ability to expand rapidly led to their high abundance following disturbance. The successful colonization of gaps by trailing blackberry was a result of its growth pattern, which focused on rapid spread as this species produced new canes annually that grew up to 1.9 m during their first year. This may allow it to be a successful colonizer of gaps. It was also capable of forming dense thickets and averaged 113 stems/m2. The growth pattern of creeping snowberry, which focused more on infilling, may allow it to maintain areas of dense, persistent cover, as it averaged 237 stems/m2 in dense thickets. It was also capable of horizontal spread through the initiation of new ramets along creeping stems. These stems averaged 0.6 m during their first year of growth. Both strategies of growth and spread allowed these shrubs to form thickets of dense vegetation. The use of stable low-growing plant communities as a management tool to reduce tree seedling establishment and growth can have many benefits including reduced costs due to lower tree density and longer periods of time between treatments, increased wildlife habitat, and aesthetic appeal. However, for this management approach to be most successful, one must have an understanding of the plant community where it is being applied, the plant characteristics that will lead to the formation of stable, low-growing communities, and how the different available treatment options will affect the resulting plant community. This study addressed many of these topics to produce a more comprehensive understanding of how stable, low-growing plant communities can be used as a management tool for reducing tree invasion in the Pacific Northwest. The two-year duration of this study, while allowing for many new insights, limited the scope of some of our conclusions. Continued monitoring of these research sites, as has been done in several locations in the northeast United States, would greatly increase the strength of our conclusions.
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2272. [Article] Understanding the impact of climate change on snowpack extent and measurement in the Columbia River Basin and nested sub basins
Shifting climate patterns in the Columbia River basin are affecting snow pack, and, as a result, stream flow throughout the region. In the Oregon Cascades, ever growing populations, and their associated ...Citation Citation
- Title:
- Understanding the impact of climate change on snowpack extent and measurement in the Columbia River Basin and nested sub basins
- Author:
- Brown, Aimee Lyn
Shifting climate patterns in the Columbia River basin are affecting snow pack, and, as a result, stream flow throughout the region. In the Oregon Cascades, ever growing populations, and their associated activities, place increasing stress on an already over allocated hydrologic system. Political pressures, including the possibility of renegotiation or termination of the Columbia River Treaty between the United States and Canada; societal pressures, including a desire for ecosystem services and fish habitat; and economic pressures, including a need for adequate streamflow for hydropower generation and irrigation, all necessitate a better understanding of current and future snow pack. This work focuses on analyzing the ability of the current snowpack measurement system to represent and capture snowpack in the Columbia River basin and its sub basins under both today’s climate and future climates. In addition, this work develops a more comprehensive knowledge of the impact climate warming will have on snow-covered areas across the region. To determine the efficacy of current snow water equivalence (SWE) measurement sites, the locations and characteristics of sites in the McKenzie River Basin, a sub basin of the Columbia River basin, were considered. SWE was distributed through the basin using the physically based model, SnowModel. SWE values at the four SNOTEL sites in the basin ranged from 0.18-0.37 m at peak SWE. Three of the sites had SWE values greater than 180% of average SWE of the snow covered area. Using elevation, aspect and slope, a 16-node binary regression tree explained controlling variables on SWE at the basin scale. As expected, elevation is the primary determinant in SWE distribution, however, the influence of different parameters shifted throughout the accumulation and ablation seasons. Updated high resolution PRISM precipitation and temperature data are used to map areas within the Columbia River basin and two nested sub basins that are at risk of turning from winter snow dominated precipitation regimes to winter rain dominated under warming scenarios ranging from 1-3°C. Within the Columbia River basin, the Oregon Cascades exhibit the greatest degree of sensitivity to changes in precipitation. Under a 2°C warming scenario, an increase that the International Panel on Climate Change finds highly likely to occur within the next 30 years, 30% of current-day snow covered area in Oregon’s Willamette River Basin will be at risk of turning from snow to rain. The water storage that will be lost if such a change does occur (0.73 km3) is equivalent to more than 8 months worth of water at the current rate of water use in the basin. Data from nine regional stations in the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) Cooperative Observer Program were used to validate placement of snow by the model. The conclusions of this work suggest that the placement of snow measurement sites requires refinement and improvement if the measurements are to accurately represent basin wide snowpack today and in the future. Water and natural resource managers will find the results presented here useful for siting future measurement locations that capture and represent SWE during times of interest. While political, societal and economic pressures will only increase, these findings provide early steps for the creation of a more robust system that has the potential to help stakeholders make informed decisions about their water resources, their communities and their needs.
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MIKE SHE is a fully distributed, physically-based hydrologic model that can simulate water movement over and under the Earth's surface. Evapotranspiration (ET) is one of the components of this model. MIKE ...
Citation Citation
- Title:
- Use of MIKE SHE for estimation of evapotranspiration in the Sprague River Basin
- Author:
- Shakya, Suva R.
MIKE SHE is a fully distributed, physically-based hydrologic model that can simulate water movement over and under the Earth's surface. Evapotranspiration (ET) is one of the components of this model. MIKE SHE uses a modification of the Kristensen -Jensen (1975) method to calculate actual ET. This method is based on addition of the three evapotranspiration components – interception storage, transpiration by the plant and evaporation from the soil surface, to compute total actual evapotranspiration. The validity of the Kristensen-Jensen method has been tested on an arid region within the Sprague River subbasin of the Upper Klamath basin in southern Oregon. The model was setup on a 1,000 m by 1,000 m flat surface as a one-dimensional grid cell. There are sixteen computation layers which make three soil profile layers with varying soil properties. Meteorological data from the Pacific Northwest Cooperative Agricultural Weather Network (AgriMet) were used to setup the model. Soil physical properties were taken from the Soil Survey Geographic (SSURGO) database of the Natural Resources Conservation Service (NRCS). Values of the van Genuchten parameters for soil water retention and hydraulic conductivity as a function of soil texture from Carsel and Parrish (1988) were applied. Wetland vegetation such as duckweed and cattail, natural vegetation such as big sagebrush, ponderosa pine and juniper, and agricultural crops such as grass pasture and maize were used to test MIKE SHE evapotranspiration simulation. The length of growth stage, crop coefficient, leaf area index (LAI) and root depth values were taken from the literature. Actual crop ET rates were calculated based on AgriMet reference ET which uses the Kimberly Penman (Wright, 1982) method. The alfalfa reference ET was converted to a grass reference by multiplying by a factor of 0.833 (Jensen et al., 1990). The single crop coefficient method was used and soil stress was accounted for using the FAO 56 method (Allen et al, 1998). Simulated irrigation was applied to maize and grass to keep the root zone soil moisture close to field capacity. Crop ET rates from the MIKE SHE simulation were then compared to the AgriMet based ET rates, resulting in a comparison of Kristensen-Jensen method against the Kimberly Penman method. Both the Kristensen-Jensen and AgriMet simulation scenarios were driven by the same reference ET and the same FAO 56 basal crop coefficient. Differences are therefore a function of different methods for dealing with soil moisture stress. Results indicate that the MIKE SHE simulated evapotranspiration corresponds to the Kimberly Penman method for the duckweed and cattail wetlands species with resulting Nash and Sutcliffe (NS) efficiencies of 0.97 and 1.00, respectively. The big sagebrush, juniper, and ponderosa pine species required a soil stress correction factor for the crop coefficients and the results yielded NS efficiency values of 0.14, 0.59 and 0.68, respectively. Irrigation was automatically turned on for maize at a 20 percent soil moisture deficit to minimize the effects of water stress and the resulting NS efficiency was 0.85. For pasture, an irrigation based on average monthly water deficit for pasture in Klamath was used (Cuenca et al.,1992). This resulted in a NS efficiency of 0.77. Each crop requires unique treatment within the model. Required vegetation parameters such as crop coefficient and LAI, climatic factors such as reference ET, and soil hydraulic properties need to be based on local conditions to the extent possible. It should be noted that the MIKE SHE simulations were run in a one-dimensional mode which precluded accounting for spatial variability or lateral flow of surface or groundwater. The simulation results indicate that converting the study area into a well irrigated pasture would require application of substantial amounts of irrigation water by sprinkler or flooding. Wetlands would require even more water to flood the land, but would be well suited for development of regional habitat. Big sagebrush, juniper and ponderosa pine survive under natural conditions but experience considerable plant stress brought on by soil water deficits which limit plant production below the maximum possible growth.
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2274. [Article] Ecological study of aquatic myxobacteria in a woodland stream
Most studies of bacteria in water have concerned public health; little attention has been given to organisms which are indigenous to the aquatic environment. Myxobacteria are known to occur in soil, in ...Citation Citation
- Title:
- Ecological study of aquatic myxobacteria in a woodland stream
- Author:
- Carlson, René Virginia
Most studies of bacteria in water have concerned public health; little attention has been given to organisms which are indigenous to the aquatic environment. Myxobacteria are known to occur in soil, in the marine environment, and several have been studied in relation to diseases of salmonid fishes. However, little information is available regarding the role of myxobacteria in the freshwater environment. The major purpose of this research was to obtain data on the occurrence, distribution, and activities of aquatic myxobacteria in a woodland stream. As a preliminary step for studying the ecology of myxobacteria in the freshwater stream, a culture medium and procedure were developed to provide a means for isolation and enumeration of these organisms. Enumeration of myxobacteria was based on the morphology of the colonies growing on the dilute nutrient medium, cytophaga peptonized milk agar (CPM). The low nutrient concentration of this medium favored spreading of the myxobacterial colony and the production of rhizoid edge patterns which are typical of myxobacteria and distinguishable from eubacterial colonies. The enumeration method was used to obtain data on the occurrence and distribution of myxobacteria as compared to the total bacteria population in Berry Creek. Results of the ecological study conducted over a two and a half year period indicate that myxobacteria are present in this aquatic environment all during the year with highest levels obtained in the fall (October and November) and lowest levels during the summer (July and August). Seasonal variations also occurred in the types of myxobacteria comprising the population of the stream. It is interesting to note that peaks in the myxobacterial and the total bacterial populations occurred in advance of the peak in flow rate. Water temperature and flow rate did not seem to influence the population levels as might be expected if the myxobacteria were transient members of the microbial flora. Additional surveys have shown that the myxobacteria are widespread in fresh water; they have been found in abundance in bottom sediments and surface films as well as in the flowing waters. Myxobacteria also appear to be well adapted to the aquatic environment. It was shown that they are able to utilize the dilute nutrients present in water for their growth. In an attempt to determine the possible role myxobacteria play in the aquatic environment, the predominant myxobacterial types were isolated and studied morphologically and biochemically. All the organisms studied corresponded to the classical definition of myxobacterial cells: gram negative, slender, weakly refractile rodshaped bacteria which exhibit gliding motility. Colony morphology of these myxobacteria plated on CPM has been studied in detail and found to be a constant characteristic of the particular type of myxobacteria isolate. Photographs of several of the predominant forms present in the stream samples illustrate the distinguishable morphology of the myxobacterial colonies. Six morphological groups have been arbitrarily designated on the basis of colony morphology; these morphological groups also show similarities in their biochemical capabilities. Biochemical studies on the myxobacterial isolates indicated that most of the strains were able to utilize simple carbohydrates. All of the isolates were capable of degrading various macromolecules, such as chitin, starch, aesculin, caesin, gelatin, and carboxy methyl cellulose. One of the isolates obtained was strictly proteolytic. The ability to hydrolyze macromolecules appears to be characteristic of aquatic isolates as well as of other myxobacteria. One myxobacterium isolated was believed to be intimately associated with the sheathed bacterium, Sphaerotilus natans. The latter organism was abundant in the sucrose and urea enriched section of Berry Creek. This myxobacterium could not utilize sucrose or urea and occurred only in the enriched section of the stream when Sphaerotilus was present. The fish pathogen, Chondrococcus columnaris was also isolated from Berry Creek water. This myxobacterium can be distinguished from the other aquatic myxobacteria on the basis of its unique colony morphology. This strain of C. columnaris proved to be one of the common serological types found in the Pacific Northwest. Based on the results obtained thus far, it is possible to speculate on the role of myxobacteria in the freshwater environment. All of the myxobacteria isolated in this study are capable of decomposing complex materials, it seems likely therefore, that these organisms may be active in the decomposition of such complex organic compounds, including the remains of other bacterial cells, which are present in the aquatic habitat. Since the isolates studied are also able to utilize the nutrients present at low levels in the stream water, these myxobacteria are not dependent on macromolecular substrates. Myxobacteria with these abilities are apparently well adapted to the aquatic environment.
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2275. [Article] Assessment of the potential for conflict between existing ocean space use and renewable energy development off the coast of Oregon
Oregon's ocean waters are a potential source of wind, wave, and tidal energy; of interest to renewable energy entrepreneurs and to the U.S. government as it seeks to bolster energy security. In order to ...Citation Citation
- Title:
- Assessment of the potential for conflict between existing ocean space use and renewable energy development off the coast of Oregon
- Author:
- Sullivan, Colleen M. (Colleen Marie)
Oregon's ocean waters are a potential source of wind, wave, and tidal energy; of interest to renewable energy entrepreneurs and to the U.S. government as it seeks to bolster energy security. In order to install technology to capture this energy, however, it may be necessary to mitigate conflict with existing ocean space users. The objective of this research was to construct a conflict analysis model in a GIS to answer the following research questions: (1) Within the study area off the coast of Oregon, where are stakeholders currently using ocean space and how many uses overlap? (2) To what extent might existing ocean space use present potential for conflict with renewable energy development? (3) How do various types of uncertainty affect analysis results? (4) What are the implications of these findings for ecosystem based management of the ocean? All available spatial information on ocean space usage by commercial fishing, commercial non-fishing, recreational, Native American, and scientific communities was gathered. Stakeholder outreach with these communities was used to vet the collected data and allow each to contribute knowledge not previously available through GIS data clearinghouses maintained by government or interest groups. The resulting data were used as inputs to a conflict visualization model written in Python and imported to an ArcGIS tool. Results showed extensive coverage and overlap of existing ocean space uses; specifically that 99.7% of the 1-nm² grid cells of the study area are occupied by at least 6 different categories of ocean space use. The six uses with the greatest coverage were: Fishing – Trolling, Habitat, Military, Fishing - Closure Areas, Protected, and Marine Transportation - Low Intensity. An uncertainty analysis was also completed to illustrate the margin for error and therefore the necessity of appropriate stakeholder outreach during the renewable energy siting process, as opposed to relying only on a GIS. Ranking of each category by its potential for conflict with renewable energy development demonstrated which areas of the ocean may be particularly contentious. Because rankings are subjective, a tool was created to allow users to input their own rankings. For the purpose of this report, default rankings were assigned to each as justified by the literature. Results under these assumptions showed that space use and potential for conflict were highest between the coast and approximately 30 nm at sea. This is likely because certain space use is limited by depth (e.g., recreational use); there is increased shipping density as vessels approach and depart major ports; and increased fuel costs associated with traveling further from shore. Two potential applications of model results were demonstrated. First, comparison with existing wave energy permit sites highlighted relative potential for conflict among the sites and the input data detailed the specific uses present. Second, comparison with areas determined most suitable for development by the wave energy industry illustrated that areas of high suitability often also had high rankings for potential for conflict. It appeared that the factors that determined development suitability were often the same factors that drew current ocean space users to those locations. Current support at the state, regional and federal level under the National Ocean Policy for the use of marine spatial planning as a tool to implement ecosystem based management of the oceans requires that tools such as the one developed in this research are used, to ensure that all components of the marine ecosystem are considered prior to implementation of a management plan. The addition of renewable energy to the current social landscape of the ocean will reduce the resource base for many categories of ocean space use. Model results demonstrated that mitigation of conflict between development and existing space use is not merely a best practice supported by current policy, but a necessity. Results presented a visualization of the social landscape of the ocean that could help managers determine which stakeholders to engage during the initial stage of choosing a site for development.
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The metabolism of Strongylocentrotus purpuratus (Stimpson) was investigated at several levels of urchin organization. Some experiments were performed with tissues from recently collected (acclimatized) ...
Citation Citation
- Title:
- Metabolic adjustment to temperature in Strongylocentrotus purpuratus (Stimpson)
- Author:
- Ulbricht, Richard Jules
The metabolism of Strongylocentrotus purpuratus (Stimpson) was investigated at several levels of urchin organization. Some experiments were performed with tissues from recently collected (acclimatized) urchins, Other experiments were performed with tissues from urchins held at one of two temperatures (acclimated) for 30 days. Body-component oxygen consumption was measured for bodywall, gut, testis, and ovary slices from seasonally acclimatized and temperature-acclimated urchins. Metabolic rates of testis and ovary underwent seasonal shifts appearing to compensate for changes in habitat temperature -- i. e., higher and lower rates during cold and warm periods, respectively. Rates of body wall and gut underwent seasonal shifts in a direction opposite those of testis and ovary -- i. e. , inverse compensation. This gonadal-nonreproductive difference was observed less conclusively with temperature-acclimated urchins. Compensatory shifts occurred with testis. Equivocal shifts occurred with body wall, gut, and ovary. Inverse compensation of metabolic rate resulted when oxygen-consumption measurements were repeated with gut slices and homogenates from temperature-acclimated urchins. Radiotracers glucose-1-¹⁴C, glucose-6-¹⁴C, and acetate- 1-¹⁴C -- were incubated with gut, testis, and ovary homogenates from temperature-acclimated urchins. Cold acclimation caused higher CO₂ and lower lipid activities in the testis. Conversely, warm acclimation caused higher CO₂ and lower lipid activities in the gut. Conversion of glucose to CO₂ was greater in gut than in testis. Conversion of acetate to lipid was generally greater in testis than in gut. Phosphogluconate oxidation and lipid synthesis relative to glycolysis and oxidation, respectively, increased in the testis following warm acclimation. Conversely, glycolysis and oxidation relative to phosphogluconate oxidation and lipid synthesis, respectively, increased in the gut following warm acclimation. Cold acclimation resulted in higher levels of glycogenesis for testis and ovary but in equivocal differences for gut. Cytochrome c oxidase activity was determined in gut, testis, and ovary extracts from seasonally acclimatized and temperatureacclimated urchins. Changes in enzyme activity paralleled those in the oxygen-consumption and radiotracer results. Gut activity was highest in September, whereas testis and ovary activities were highest in December and March, respectively. Gut activity was higher following warm acclimation, but testis and ovary activities were higher following cold acclimation. Glucose 6-phosphate dehydrogenase (G6PDH) activity was determined in gut, testis, and ovary extracts from temperature-acclimated urchins. Changes in G6PDH activity were the reverse of those in the oxygen-consumption, radiotracer, and cytochrome c oxidase results, suggesting that changes in the effectiveness with which glycolysis and phosphogluconate oxidation compete for the common substrate, glucose 6-phosphate (G6P), may compensate for each other. Warm acclimation generally increased gonadal G6PDH activity but failed to alter gut activity. Gonadal G6PDH activity was generally much higher than was that of the gut. The apparent G6PDH-G6P affinity for gut, testis, and ovary was increased following cold acclimation. Body-component weights were determined from the urchins used in the metabolic rate-season studies. Gonadal ash-free dry weights expressed as a percentage of the total were maximal in the fall and minimal in the spring, whereas those of the body wall were maximal in the spring and minimal in the fall. Seasonal changes in the gut were negligible by comparison. The above temperature-induced changes in urchin metabolism are discussed relative to temperature-induced changes in whole-urchin metabolism and to situations confronting intertidal populations of urchins. Gonadal catabolism appears maximal in the winter or spring and minimal in the fall, whereas gonadal anabolism appears maximal in the fall and minimal in the spring. Nonreproductive catabolism appears maximal in the fall and minimal in the winter, whereas nonreproductive anabolism appears maximal in the spring and minimal in the fall.
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2277. [Article] Seasonal life history of Oncorhynchus mykiss in the South Fork John Day River Basin, Oregon
Understanding seasonal changes in growth, survival, and movement rates is crucial to salmonid management. These life history characteristics provide a context for evaluation of management actions. We evaluated ...Citation Citation
- Title:
- Seasonal life history of Oncorhynchus mykiss in the South Fork John Day River Basin, Oregon
- Author:
- Tattam, Ian A.
Understanding seasonal changes in growth, survival, and movement rates is crucial to salmonid management. These life history characteristics provide a context for evaluation of management actions. We evaluated the life history of individually marked Oncorhynchus mykiss gairdneri in the South Fork John Day River basin in Northeastern Oregon. This thesis focuses on Murderers and Black Canyon creeks, two tributaries to the South Fork John Day. These are semi-arid, mid elevation basins with naturally reproducing populations of summer steelhead and redband trout (both O. mykiss). Summer steelhead populations in this basin have declined from historic abundances, and are protected under the Endangered Species Act. In Chapter 2, we evaluate life history variation in Murderers Creek during four consecutive seasons. Growth rate varied significantly with season (F[subscript 3,88] = 62.56, P < 0.0001), with most growth occurring during spring. Location and season interacted F[subscript 6,88] = 4.45, P < 0.001) to influence individual growth rates. As a result, regions of high growth potential shifted up and down-stream seasonally. However, we found low rates of O. mykiss movement (<3%) in Murderers Creek during summer, suggesting that individuals did not track resource availability at a large scale. Apparent survival rate varied among reaches, but was consistently higher in the upstream most reach compared to the two lowermost reaches. Survival rates were similar between summer and fall, indicating that declining fall temperatures did not increase mortality. A shift in population distribution occured during fall (September through December), as some O. mykiss emigrated from tributaries into the mainstem South Fork John Day River. In Chapter 3, we investigate differences in fall life history between and within tributaries. A significantly greater proportion of O. mykiss emigrated from Murderers Creek compared to Black Canyon Creek during two consecutive years (P < 0.001 for both years). There were no significant differences in proportion of emigrants between years within either stream (P > 0.10 for both streams). In Murderers Creek, odds of emigration were related to stream reach of summer residence. Odds of fall emigration were also significantly and positively related to body length in fall and growth rate during summer. This suggests that competitive dominants volitionally emigrated from Murderers Creek during fall. After emigration, O. mykiss dispersed primarily further downstream into the Mainstem John Day River. Radio-telemetry indicated that the majority of fall emigrants occupied a < 6 km section of the Mainstem John Day River. Fall emigrants had growth rates during their winter niche shift that were significantly (P < 0.001) higher than those of individuals remaining in tributaries. This study underscores the need to monitor during all seasons to accurately characterize habitat quality. Life history patterns are an important population response to environmental change. This thesis provides an ecological context for monitoring recovery of O. mykiss populations in the South Fork John Day River basin.
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2278. [Article] An investigation of the utilization of four study areas in Yaquina Bay, Oregon, by hatchery and wild juvenile salmonids
Results of a study of spatial and temporal utilization of a tidal river estuary by hatchery and wild juvenile salmonids (Oncorhynchus spp. and Salmo spp,), of overlap in food habits of hatchery and wild ...Citation Citation
- Title:
- An investigation of the utilization of four study areas in Yaquina Bay, Oregon, by hatchery and wild juvenile salmonids
- Author:
- Myers, Katherine West Whitney
Results of a study of spatial and temporal utilization of a tidal river estuary by hatchery and wild juvenile salmonids (Oncorhynchus spp. and Salmo spp,), of overlap in food habits of hatchery and wild juvenile salmonids, and of size and relative abundance of associated fish species are reported in this thesis. The investigation was conducted in Yaquina Bay, Oregon in 1977 and 1978 to provide information for evaluation of concerns over the biological impact of large releases of hatchery salmon on wild fish in the estuary. A 100- X 3-m beach seine was used to sample four beach study areas from July 1977 through December 1978, and a 222-m lampara net was used to sample two channel study areas from March 1978 through October 1978. Approximately 2. 2 million hatchery salmon were released into Yaquina Bay in 1977, and 9.6 million were released in 1978. Tags, fin clips, dye marks, scales, species, release date, external parasites, visceral fat, size, and fin erosion were used to determine hatchery or wild origin of individual salmonids in the catch. Chinook (Oncorhynchus tshawytscha), chum (0. keta), and coho (0. kisutch) salmon, in decreasing order, were the most abundant wild salmonid species, and coho salmon were the most abundant hatchery species. In 1978 wild populations of chum and coho salmon were present in the estuary for 2-3 mo (March-June), and wild Chinook were present during 9 mo (January, April-November). Increase in mean length of wild chum and Chinook, and decrease in mean length of wild coho, indicated that wild chum and Chinook utilized the estuary as a rearing area, and wild coho did not. Lack of overlap in peak migration periods of wild chum (early April), coho (mid May), and chinook (late July-early August) suggests the need to minimize overlap in utilization of the estuary by hatchery and wild juvenile salmonids. The length of residence of hatchery coho in Yaquina Bay was described by the equation: N=N 0 e-kt. The "residency half-life" (E®2) ranged from 1. 7 to 9. 0 days for different No release groups of hatchery coho in 1977 and 1978. Juvenile hatchery coho that remained for an extended period (1-3 mo) in Yaquina Bay during 1977 increased in mean length from 11.5 cm FL in mid July to 21. 0 cm FL in October. Some individuals within summer release groups of hatchery chinook also remained in the estuary for extended periods (> 2 mo)a Groups of juvenile hatchery coho and chinook released into Yaquina Bay earlier in the year (June-August) remained in the estuary for longer periods than groups released later in the year (September-October), Overlap in food habits of hatchery and wild juvenile salmonids in the estuary was C ften high, although overlap was found to vary with species, time, habitat, space, length of estuarine residence, and prey abundance. In terms of biomass, larval and juvenile fish (Clupeidae, Engraulidae, and Osmeridae) were the most important prey organisms of hatchery and wild coho and chinook salmon in Yaquina Bay. Approximately 58 fish species were captured at the study areas in 1977 and 1978, and 17 were identified in the stomach contents of hatchery and wild salmonids. Overlap in spatial and temporal utilization and in food habits of hatchery and wild juvenile salmon in the estuary indicates that the potential for competition between these groups does exist, should space or food resources become a limiting factor. To reduce overlap in spatial and temporal utilization, consideration should be given to not releasing hatchery salmon during peak migration periods of wild chum, coho, and chinook salmon. To reduce length of residence of hatchery coho and chinook released after May, mid to late summer releases should be considered.
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2279. [Article] Eelgrass-macroalgae interactions; context-dependency in upwelling-influenced estuaries
This dissertation investigates the context-dependency of species interactions between seagrass and macroalgae in upwelling-influenced estuaries. In all coastal systems, nutrient loading is multidirectional, ...Citation Citation
- Title:
- Eelgrass-macroalgae interactions; context-dependency in upwelling-influenced estuaries
- Author:
- Hessing-Lewis, Margot, 1979-
This dissertation investigates the context-dependency of species interactions between seagrass and macroalgae in upwelling-influenced estuaries. In all coastal systems, nutrient loading is multidirectional, resulting from mostly freshwater and marine inputs. The directionality of nutrient inputs may affect the rate of supply of organic matter to the system. In systems where freshwater nutrient loading dominates, and has increased through time, research shows that blooms of fast-growing macroalgae often result in loss of critical seagrass habitats. In upwelling-influenced systems, marine- based nutrient inputs dominate during the summer, also resulting in blooms of ulvoid macroalgae during these productive months. The dominance of marine nutrients in these estuaries, coupled with additional variation in the physicochemical characteristics of seagrass beds, present novel contexts to study the outcomes of species interactions between the seagrass (Zostera marina L. (eelgrass) and ulvoid macroalgae. I studied these interactions at two different spatial scales that both address the relative importance of marine versus terrestrial nutrient sources on interaction outcome. Regionally, I studied between-estuary, latitudinal patterns in species interactions relative to differences in marine and terrestrial drivers of nutrient loading. Within an estuary, I also compared interactions among zones along an estuarine gradient, where nutrient patterns were reflective of the relative contribution of marine- based nutrients. At both scales of inquiry I employed both observational and experimental approaches to quantify species interaction dynamics. At the regional scale, I used a 5- year observational dataset from four estuaries along the Oregon and Washington coasts to study the relationship between eelgrass and ulvoid macroalgae (Chapter 2). Across latitudes that span ~220 km, macroalgal production was highest in the southern estuaries, and associated with decreased eelgrass production compared to the northern estuaries. However, through time, no estuarine site, regardless of its macroalgal biomass, was associated with declining eelgrass biomass. Contrary to systems where macroalgal production is driven by terrestrial inputs, I found that blooms in upwelling- influenced systems were associated with both marine and terrestrial drivers of nutrient inputs and production. In Coos Bay (South Slough), at the within-estuary scale, I also found differences in macroalgal and eelgrass biomass among sites along an estuarine gradient. Here too, based on a 2-year seasonal dataset of producer dynamics, I found no temporal relationship between eelgrass and macroalgae producer dynamics (Chapter 3). I used a comparative-experimental framework to understand the impact of macroalgal manipulations (additions and removals) on interactions with eelgrass along this gradient. In intertidal seagrass beds in the marine and polyhaline zones of the estuary I found that interaction strength was neutral and sometimes positive. However, in the riverine zone, interaction strength was negative, caused by decreased eelgrass density following macroalgal manipulation. To further examine the mechanisms informing interaction outcomes in the marine zone, a large-scale macroalgal manipulation was conducted, coupled with a mesocosm experiment (Chapter 4). For the mesocosm experiment I manipulated macroalgae and nutrients as in the field, but found dissimilar results. In the mesocosms, where water movement was limited and no tidal action occurred, negative effects of macroalgal addition were found. These were associated with increased light attenuation and decreased sediment oxygen levels. Contrary to these results, I found no macroalgal, or covariate effects in the field experiment. I also manipulated water column nutrients in both experiments, and found limited effects of nutrient enrichment on eelgrass, but not macroalgae, in the mesocosm experiment. Throughout these studies I demonstrated that the mechanisms determining context-dependency in upwelling-influenced estuaries are informed by physical and biogeochemical conditions, coupled with high ambient marine-derived nutrient concentrations. These findings are important to coastal management because they suggest that the strength, direction and mechanisms of interactions are shaped by local abiotic conditions and long-term nutrient regimes, rather than high nutrient concentrations per se. Given the shifting nature of nutrient concentrations in coastal waters associated with both coastal development and climate change, knowledge of context dependency can also be used to assess and forecast future changes in species interactions.
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The United States Pacific Northwest is well known for its shellfish farming. Historically, commercial harvests were dominated by the native Olympia oyster, Ostrea lurida, but over-exploitation, habitat ...
Citation Citation
- Title:
- Identification of optimal broodstock for Pacific Northwest oysters
- Author:
- Stick, David A.
The United States Pacific Northwest is well known for its shellfish farming. Historically, commercial harvests were dominated by the native Olympia oyster, Ostrea lurida, but over-exploitation, habitat degradation, and competition and predation by non-native species has drastically depleted their densities and extirpated many local populations. As a result, shellfish aquaculture production has shifted to the introduced Pacific oyster, Crassostrea gigas. An underlying objective of this dissertation is the use of molecular genetics to improve our ability to accurately identifying optimal oyster broodstock for either restoration of Olympia oysters or farming of Pacific oysters. The ecological benefits provided by oysters as well as the Olympia oyster's historical significance, has motivated numerous restoration/supplementation efforts but these efforts are proceeding without a clear understanding of the genetic structure among extant populations, which could be substantial as a consequence of limited dispersal, local adaptation and/or anthropogenic impacts. To facilitate this understanding, we isolated and characterized 19 polymorphic microsatellites and used 8 of these to study the genetic structure of 2,712 individuals collected from 25 remnant Olympia oyster populations between the northern tip of Vancouver Island BC and Elkhorn Slough CA. Gene flow among geographically separated extant Olympia oyster populations is surprisingly limited for a marine invertebrate species whose free-swimming larvae are capable of planktonic dispersal as long as favorable water conditions exist. We found a significant correlation between geographic and genetic distances supporting the premise that coastal populations are isolated by distance. Genetic structure among remnant populations was not limited to broad geographic regions but was also present at sub-regional scales in both Puget Sound WA and San Francisco Bay CA. Until it can be determined whether genetically differentiated O. lurida populations are locally adapted, restoration projects and resource managers should be cautious of random mixing or transplantation of stocks where gene flow is restricted. As we transition from our Olympia oyster population analysis to our Pacific oyster quantitative analysis, we recognize that traditional quantitative trait locus (QTL) mapping strategies use crosses among inbred lines to create segregating populations. Unfortunately, even low levels of inbreeding in the Pacific oyster (Crassostrea gigas) can substantially depress economically important quantitative traits such as yield and survival, potentially complicating subsequent QTL analyses. To circumvent this problem, we constructed an integrated linkage map for Pacific oysters, consisting of 65 microsatellite (18 of which were previously unmapped) and 212 AFLP markers using a full-sib cross between phenotypically differentiated outbred families. We identified 10 linkage groups (LG1-LG10) spanning 710.48 cM, with an average genomic coverage of 91.39% and an average distance between markers of 2.62 cM. Average marker saturation was 27.7 per linkage group, ranging between 19 (LG9) and 36 markers (LG3). Using this map we identified 12 quantitative trait loci (QTLs) and 5 potential QTLs in the F1 outcross population of 236 full-sib Pacific oysters for four growth-related morphometric measures, including individual wet live weight, shell length, shell width and shell depth measured at four post-fertilization time points: plant-out (average age of 140 days), first year interim (average age of 358 days), second year interim (average age of 644 days) and harvest (average age of 950 days). Mapped QTLs and potential QTLs accounted for an average of 11.2% of the total phenotypic variation and ranged between 2.1 and 33.1%. Although QTL or potential QTL were mapped to all Pacific oyster linkage groups with the exception of LG2, LG8 and LG9, three groups (LG4, LG10 and LG5) were associated with three or more QTL or potential QTL. We conclude that alleles accounting for a significant proportion of the total phenotypic variation for morphometric measures that influence harvest yield remain segregating within the broodstock of West Coast Pacific oyster selective breeding programs.
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2281. [Article] A cooperative effort to track Humboldt squid invasions in Oregon
Interannual variability of Humboldt squid (Dosidicus gigas) occurrence in the northern California Current System is largely unknown. In Oregon, the distribution of this versatile predator and what is influencing ...Citation Citation
- Title:
- A cooperative effort to track Humboldt squid invasions in Oregon
- Author:
- Chesney, Tanya A.
Interannual variability of Humboldt squid (Dosidicus gigas) occurrence in the northern California Current System is largely unknown. In Oregon, the distribution of this versatile predator and what is influencing their range expansion from Mexico is poorly understood due to the recent nature of their "invasion" and a lack of monitoring. Humboldt squid are large predators that have the potential to affect ecosystem structure and fisheries because of their high-energy demands and ability to exploit a variety of oceanographic conditions and prey sources. Developing baseline distribution information is a critical first step to assess their potential ecological, social, and economic impacts, and to develop models to predict future range expansion. This study has two main objectives: (1) to document where and when Humboldt squid have been present in Oregon through cooperative fisheries research, and (2) to correlate the sightings with oceanographic conditions using a geographic information system (GIS) and species distribution modeling (SDM). I conducted 54 interviews with local fishermen and aggregated their squid sightings with available fishery-independent survey and fishery-dependent observer data from the National Marine Fisheries Service. I compiled a total of 339 Humboldt squid sightings, reported for the years 2002-2011 from the Oregon coast to 131° west longitude. Correlation analyses were performed for Humboldt squid sightings and sea surface temperature (SST), chlorophyll a content (chla), sea surface height anomalies (SSH), dissolved oxygen at 30 m depth (30 m DO), and sea surface salinity (SSS) using a GIS, nonparametric multiplicative regression (NPMR) habitat modeling, and maximum entropy modeling (Maxent). Results indicate that oceanographic conditions have the potential to influence Humboldt squid occurrence, and in Oregon, sightings vary temporally and spatially. Combining the sightings from fishermen and scientific surveys greatly enhanced the spatial extent of the data. Humboldt squid were most frequently observed between 124.4°W and 125°W in proximity to the shelf-break at the 200 m isobath, with peak sightings (116) recorded in 2009 and the fewest (6) reported in 2003 and 2011. The highest occurrence of Humboldt squid were observed at a SST of 10.5-13.0°C, 0.26-3.0 mg m⁻³ chla content, -4.0-1.0 m SSH anomalies, 32.2-32.8 psu SSS, and at 3-4.5 ml L⁻¹ and 6-7 ml L⁻¹ 30 m depth DO. Maps of estimated likelihood of occurrence generated by NPMR were consistent with overlayed observations from fishermen, which were not used in the model because they were limited to presence-only information. An interdisciplinary approach that incorporates cooperative fisheries research and ecosystem-based management is necessary for monitoring Humboldt squid in Oregon. Traditional methods are insufficient because Humboldt squid are data-poor, highly migratory, and are main predators of many commercially important fisheries in Oregon. Based on my findings, sightings recorded by fishermen covered a much larger area over a longer time frame than the scientific survey and observer data, and excluding their knowledge would have led to a different interpretation of Humboldt squid distribution and environmental tolerances. Although there is uncertainty in the data from potential map bias or misidentification of smaller Humboldt squid, incorporating sightings from fishermen with traditional fisheries research increases the quantity and quality of information. Cooperative monitoring for Humboldt squid could include training in species identification and sea condition reporting in logbooks. Future "invasions" are likely, and more eyes on the water will improve our understanding of the behavior and impacts of Humboldt squid on coastal resources.
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This study delineates and characterizes the distribution of montane meadows in the Willamette National Forest, identifies encroachment patterns in relation to topographic features and proximity to trees ...
Citation Citation
- Title:
- Meadow classification in the Willamette National Forest and conifer encroachment patterns in the Chucksney-Grasshopper meadow complex, Western Cascade Range, Oregon
- Author:
- Dailey, Michele Meadows
This study delineates and characterizes the distribution of montane meadows in the Willamette National Forest, identifies encroachment patterns in relation to topographic features and proximity to trees in the Chucksney-Grasshopper meadow complex, and examines tree species and age distributions in relation to distance from forest edges or isolated tree clusters in the West Middle Prairie meadow. The Willamette National Forest covers approximately 6780 km² and intersects two main physiographic provinces comprised of the Cascade Crest Montane Forests and Subalpine/Alpine regions to the east, and the Western Cascades Montane, Lowland, and Valley regions to the west. Tree species commonly found in the study area include firs, cedar, pine, larch, spruce, and hemlock. Non-forested openings, including meadows, are distributed throughout the study area. Matched Filtering analysis was applied to Landsat ETM+ imagery acquired in September 2002 and combined with ancillary data that delineates stand replacing fire and harvest disturbances that occurred between 1972 and 2004 to create a vegetation classification of the Willamette National Forest that identifies meadows. The meadow classification was then combined with data depicting topographic position, slope, aspect, and elevation. Chi-squared statistics were applied to determine if meadows were significantly concentrated in areas characterized by these physical factors. In the western extent of the Willamette National Forest, meadows are concentrated on steep, south and east facing ridges between 1000 and 2000m in elevation. In the eastern extent of the Willamette National Forest, meadows are concentrated in valleys between 500 and 1000 meters in elevation and occur on both gentle and steep, east and south facing slopes. The vegetation classification provides a consistent and comprehensive dataset of meadow distribution in the Willamette National Forest. The Chucksney-Grasshopper meadow complex is contained by the Chucksney Mountain roadless area and comprised of approximately 8 distinct meadows located 27 kilometers northeast of Oakridge in the Willamette National Forest. The meadows occur on mostly south and east facing steep slopes near the ridgeline, and host varied dry and mesic plant communities. Herbaceous cover for three snapshots in time was classified using aerial photographs taken in 1947, 1972, and 2005 to determine conifer encroachment into the meadows. Chi-squared statistics were applied to determine if encroachment patterns were associated with slope, aspect, or proximity to tree cover. Encroachment occurred significantly closer to existing trees in all meadows suggesting the ameliorating effects of forest create conditions favorable for seedling establishment. Encroachment was also significant on steep, south and east facing slopes in some meadows, but also on gentle, west facing slopes in other meadows indicating a complex interaction of land use history, physical, and biological factors. The encroachment history analysis provides the preliminary framework for a model that can be used to identify meadows at risk for invasion. The West Middle Prairie of the Chucksney-Grasshopper complex, also known as Meadow 4, is a 21 hectare meadow characterized by a dry meadow community at the northern boundary, a mesic forest-meadow mosaic towards the southern boundary, and a rock garden at the western boundary. This meadow underwent mechanical tree removal in 1964 and a prescribed burn in 1996 to thwart conifer invasion. Four transects intersecting burned and unburned areas at the forest edge and through isolated tree clusters were sampled to determine the distribution of tree species and ages relative to their position in the transect. Data imply Pinus contorta invasion was promoted by the 1996 burns and that seedling establishment has occurred progressively from forest edges as well as simultaneously in a band along the forest edge. These findings suggest the prescribed burn was not adequate to control invasion and such management methods should be reviewed in the context of on-going research into alternate eradication measures. This research also supports other work that suggests initial seedling establishment accelerates subsequent seedling establishment and that eradication of early invaders is important for efficient management. This study can inform meadow habitat maintenance and restoration in three ways: it provides and inventory of meadows in the Willamette National Forest, a framework for a tool to predict which meadows are at risk for invasion and therefore are potential targets for action, and finally a report on past maintenance efforts and observation of invasion patterns at a fine scale.
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2283. [Article] Forest-meadow dynamics in the central western Oregon Cascades : topographic, biotic, and environmental change effects
Montane meadows comprise a small area of the predominantly forested landscape of the Oregon Cascade Range. Tree encroachment in the last century in these areas has threatened a loss of biodiversity and ...Citation Citation
- Title:
- Forest-meadow dynamics in the central western Oregon Cascades : topographic, biotic, and environmental change effects
- Author:
- Rice, Janine, M.
Montane meadows comprise a small area of the predominantly forested landscape of the Oregon Cascade Range. Tree encroachment in the last century in these areas has threatened a loss of biodiversity and habitat. Climate change in the coming century may accelerate tree encroachment into meadows, and exacerbate biodiversity loss. Multiple environmental factors of topography, biotic interactions, climate, and disturbance, whose interactions and impacts are unclear, influence forest encroachment into meadows. This dissertation examines these complex interactions and factors in two montane meadow ecosystems at Lookout (44º 22′N, 122º 13′W) of the Western Cascade Range and Bunchgrass (44º 17′N, 121º 57′W) of the High Cascade Range of Oregon. A change detection analysis quantifies how topographic factors and proximity to edge were related to tree encroachment into the two montane meadows of the Cascade Range of Oregon. Areas that have experienced tree encroachment were identified and partitioned by distance to forest edge, aspect, and slope class using historical air photo interpretation over 54 years from 1946, 1967, and 2000 at Lookout and Bunchgrass meadows in the western Cascades of Oregon. Meadow area decreased by more than 1% per year, with a net decrease of 60%, and a net loss of 22 ha at Lookout Meadow and 28 ha at Bunchgrass Meadow from 1946 to 2000. From 72% (Lookout) to 77% (Bunchgrass) of meadow area within 5 m of a forest edge became forest by 2000. Twothirds to three-quarters of meadow area on south and west aspects at both sites converted to forest from 1946 to 2000. Two-thirds of meadow conversion to forest from 1946 to 2000 occurred on slopes <6° at Bunchgrass Meadow, but meadow conversion to forest was more evenly distributed among slope classes at Lookout Meadow. Restoration efforts may need to focus on westerly or southerly aspects in areas < 5 m from the forest edge. The effects of biotic interactions and climate on the spatial patterns of two species (Lodgepole pine and Grand fir) were tested at Bunchgrass Meadow, a 37-ha meadow complex in the High Cascades of Oregon. A spatial analysis was used to quantify spatial patterns of more than 900 saplings and trees of these two species that had established since 1916 in a 0.21 ha early tree succession area. The light- and heat-tolerant species, Lodgepole pine, tended to establish initially and at relatively longer distances from other trees; Lodgepole seedlings avoided establishment within 2 m of >35-yr-old Grand fir. In contrast, the shade-tolerant species, Grand fir, tended to establish subsequently at relatively short distances to other trees, and was closely associated with older trees of both species. Lodgepole pine establishment was associated with warm, dry late summers, while Grand fir establishment was associated with wet springs and cool summers. Tree encroachment was regulated by both climate variability and biotic interactions responding to species’ environmental tolerances. Environmental tolerances influenced the rate of tree species establishment in the meadow, but biotic interactions were more important than exogenous factors, such as climate, in controlling the spatial patterns of encroachment dynamics. The relative contributions of climate change, atmospheric CO2 concentrations, and fire regimes, and their interacting effects on past and future non-forested areas were investigated with a modeling experiment. A generalized ecosystem model, LPJ-GUESS, was used to disentangle the impacts of environmental drivers (increased temperature, increased atmospheric CO2 concentrations, and changing fire frequency) on primary production, biomass, and extent of meadow (non-forest area) at a site representing montane meadow and forests of the western Cascades of Oregon. Model projections based on a moderately high future-warming scenario (4 °C increase from 2000 to 2100) indicated that fire disturbance played the largest role in reducing projected forest area and expanding non-forested areas, while fire suppression had the largest opposite effect. Increased temperature altered species composition to higher temperature-tolerant tree species, but it did not have a significant effect on the projected extent of forest or nonforest areas. Increased atmospheric CO2 concentration increased forest biomass, but it did not significantly change the projected extent of non-forest area. Projected changes in the extent of forest and non-forest areas lagged behind the potential impacts of environmental changes on primary production and biomass. The net effects of potential future environmental factors point to a continued expansion of forests and reduction of non-forested areas if fire suppression is maintained. The use of fire or tree removal may continue to be required to preserve these unique and vital meadow ecosystems of the Oregon Cascades.
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2284. [Article] An ecological study of Diatomovora amoena, an interstitial acoel flatworm, in an estuarine mudflat on the central coast of Oregon
The distribution and abundance of the interstitial acoel turbellarian, Diatomovora amoena Kozloff, 1965 was studied in an estuarine intertidal sand flat in Yaquina Bay, Oregon, from May 1970 through May ...Citation Citation
- Title:
- An ecological study of Diatomovora amoena, an interstitial acoel flatworm, in an estuarine mudflat on the central coast of Oregon
- Author:
- Thum, Alan Bradley
The distribution and abundance of the interstitial acoel turbellarian, Diatomovora amoena Kozloff, 1965 was studied in an estuarine intertidal sand flat in Yaquina Bay, Oregon, from May 1970 through May 1971. Monthly measurements of biological (organics, sulfides, chlorophyll, and carotenoids), pore water (salinity, pH,oxygen, and temperature), and sediment (fine sediment percentage, grain size, sorting, skewness, and kurtosis) factors were made along a transect at four intertidal stations with elevations of -2.0, 0.0, 1. 6, and 3.0 feet, stratified by selection from a curve for tidal exposure, and at two depths (0, 0 cm to 0. 5 cm and 0. 5 cm to 1. 0 cm) of the sediment. Estuarine factors that were monitored continuously included temperature, salinity, tide elevation, and insolation. The interrelationships among these environmental parameters, their roles in the interstitial sediment system, and the hydrology of the groundwater in the beach, were investigated in order to characterize the interstitial environment of the sand flat and to determine the environmental factors limiting the distribution and abundance of D. amoena. Seasonality was indicated in most of the factors measured. The sediment system was strongly reducing during summer and fall as organic production increased. Particle size analyses showed that transport and deposition of fine sediments contributed to the development of reducing conditions. The properties of the interstitial environment of D. amoena were found to be controlled by the level of groundwater, rate of percolation, and degree of mixing within the beach. Density of D. amoena was highest during the fall and early winter, and lowest throughout the winter. Summer production of plant material in the lower intertidal lead to reducing conditions at the sediment surface. Reduction in animal density at the lower two stations was attributed to these reducing conditions, and to the rafting of animals away from the intertidal with the algal mat. Decrease in animal density in the upper two stations was attributed to lethal low temperatures and salinities that occurred during heavy precipitation in the winter and coincided with low tidal exposure. Exclusion of animals from depths greater than 0. 5 cm in the sediment was attributed to lethal levels of sulfide. Tolerance of D. amoena to temperature, salinity, and sulfide was determined experimentally. The 25 combinations of temperature and salinity, and the 12 combinations of temperature and sulfide that were employed were selected on the basis of actual levels measured in the study area. The temperature and salinity survival results were fitted to a response surface which was used to evaluate these factors in limiting animal distribution. Survival of acoels was independent of temperature up to 6 hours of exposure, and strongly temperature-dependent after 24 hours of exposure. Initial mortality was attributed to osmotic stress. Upon exposure to sulfide at 50 μgm S/ml, these animals did not survive beyond 6 hours, demonstrating that sulfide in high concentrations is toxic to D. amoena. At lower concentrations of sulfide (10 μgm S/ml), the acoels were able to live for over 20 hours. Lowering the temperature at both concentrations helped to prolong the lives of the animals. Levels of sulfide similar to those used in the experiment Levels of sulfide similar to those used in the experiment (10 μgm S/0.5 cm³ = 50 μgm S/ml.) were found at the sediment surface in the lower two stations during September, at which time animal density was found to be decreasing. At the upper two stations in September, where the level of sulfide was 3 μgm S/0.5 cm³, the acoel population was found to be increasing, thus bearing out the assumption that population density is, indeed, affected by sulfide. The nature of the interstitial sediment system as a habitat for meiofaunal organisms was explored and the role of the groundwater hydrology, as a buffer against seasonal variation in the estuary, in maintaining this system was examined. A portion of the littoral shore considered in this investigation was conceptualized as a factor model, the principal parts of which were selected for study. The seasonal cycles of the major input factors were found to be relatively stable from year to year, while the timing of these cycles varied. The numerous positive and negative correlations that were found within and between the biological, pore water, and sediment groups of factors indicated the multiplicity of direct and indirect interactions and supported the contention that the tidal flat is a complex interrelated system. Change in one or more of the major factors, such as precipitation, river runoff, sedimentation, or tidal prism, can be expected to have diverse effects on the littoral sediment environment.
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2285. [Article] Variation in the timing of coho salmon (Oncorhynchus kisutch) migration and spawning relative to river discharge and temperature
Coho salmon (Oncorhynchus kisutch) migration and spawning are unique components of the salmon life cycle because they require synchrony of behavior with other individuals as well as with acceptable fluvial ...Citation Citation
- Title:
- Variation in the timing of coho salmon (Oncorhynchus kisutch) migration and spawning relative to river discharge and temperature
- Author:
- LovellFord, Rachel
Coho salmon (Oncorhynchus kisutch) migration and spawning are unique components of the salmon life cycle because they require synchrony of behavior with other individuals as well as with acceptable fluvial conditions. As with other organisms that exhibit group mating behavior, it is likely that environmental cues trigger coho salmon movement to spawning grounds. These cues may also provide usable habitat for migration and spawning. River discharge, temperature, and length of day have long been assumed to be the environmental cues which trigger migration and spawning of coho salmon as coho return within the same season each year to spawn. Hatchery studies have also shown that the timing of reproductive behavior is heritable. If this heritability is determined by the fluvial conditions of the spawning grounds, then a predictable relationship should exist between reproductive behavior and the hydrologic and thermal regimes. Surprisingly, no defensible correlations between discharge thresholds and spawning or migrating activity have been identified for naturally reproducing coho salmon. Thermal, velocity, and depth limitations have been identified for coho salmon, but these values have not been examined in combination or within the context of a hydrologic and thermal regime. This study compares interannual patterns in the timing of coho mid-river migration in the North Umqua (180 km up river from the estuary) and the initiation of spawn timing in the Smith River basins (Oregon) with river discharge and water temperature data to ascertain whether these behaviors are driven by fluvial conditions. Additionally, we used this data to identify the window over which most migration and spawning takes place in our test systems. On the North Umpqua, coho salmon mid-river migration initiated (first 5% of migrants) after summer peak temperatures and following a threshold average daily temperature of 18 C°, but before fall storm events occurred. In most years, approximately 75% of the migrating coho salmon have moved past the Winchester Dam before fall storms initiated and when discharge remained less than the 11 year average for the month of November, more similar to summer than winter flow levels. Additionally, characteristic lengths and numbers of peaks within the distribution of annual migrations were attributable to the generational cohort that the migration belonged to despite the similarity in population size across all years. These patterns in the distribution of generational cohorts suggest an inherited timing response as well as highlight cohorts which may contain diminished sub-populations. The initiation of coho salmon spawning appears limited both by a thermal threshold of 12 C° in all basins, as well as by a minimal discharge threshold, which is unique to each stream. Continued spawning activity occurs as discharge remains elevated from fall levels. It is also notable that there was no statistical difference in the date of the initiation of spawning within each basin in a given year or across years at a given site. Together, these studies highlight the important role that the coho salmon genome plays in reproductive timing as well as the ways that fluvial thresholds limit reproductive behavior in time. Coho have survived because of their genome has been resilient when faced with environmental change. Future work should consider variability in fluvial conditions relative to coho salmon phenotypic plasticity over time. Coho salmon phenotypic plasticity will determine whether the rate of change of the hydrologic and thermal regimes important to coho salmon survival outpaces the coho’s ability to adapt. This study contributed to this future work by establishing baseline relationships between the behavior of a threatened species and measurable environmental thresholds.
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2286. [Article] Larval dispersal in marine fishes: novel methods reveal patterns of self-recruitment and population connectivity
Many marine fish populations are severely declining due to over-fishing, loss of both juvenile and adult habitats, and accelerating environmental degradation. Fisheries management and the implementation ...Citation Citation
- Title:
- Larval dispersal in marine fishes: novel methods reveal patterns of self-recruitment and population connectivity
- Author:
- Christie, Mark R.
Many marine fish populations are severely declining due to over-fishing, loss of both juvenile and adult habitats, and accelerating environmental degradation. Fisheries management and the implementation of marine protected areas (MPAs) and other conservation tools are currently hindered by large gaps in knowledge about larval dispersal and its subsequent effects on population dynamics and regulation. This lack of knowledge is due to the inherent difficulty associated with tracking miniscule marine fish larvae. Population genetics approaches are particularly promising, but current methods have been of limited use for inferring ecologically relevant rates of population connectivity because of the large population sizes and high amounts of gene flow present in most marine species. To address these issues, I developed novel genetic methods of identifying parent-offspring pairs to directly track the origin and settlement of larvae in natural populations. These parentage methods fully account for large numbers of pair-wise comparisons and do not require any demographic assumptions or observational data. Furthermore, these methods can be used when only a small proportion of candidate parents can be sampled, which is often the case in large marine populations. I also employed Bayes’ theorem to take into account the frequencies of shared alleles in putative parent-offspring pairs, which can maximize statistical power when faced with fixed numbers of loci. I accounted for genotyping errors by introducing a quantitative method to determine the number of loci to allow to mismatch based upon study-specific error rates. These novel parentage methods were applied to yellow tang (Zebrasoma flavescens, Acanthuridae) sampled around the Island of Hawai'i (measuring 140 km by 129 km) during the summer of 2006. We identified four parent-offspring pairs, which documented dispersal distances ranging from 15 to 184 kilometers. Two of the parents were located within MPAs and their offspring dispersed to unprotected areas. This observation provided direct evidence that MPAs can successfully seed unprotected sites with larvae that survive to become established juveniles. All four offspring were found to the north of their parents and a detailed oceanographic analysis from relevant time periods demonstrated that passive transport initially explained the documented dispersal patterns. However, passive dispersal could not explain how larvae eventually settled on the same island from which they were spawned, indicating a role for larval behavior interacting with fine-scale oceanographic features. Two findings together suggested that sampled reefs did not contribute equally to successful recruitment: (1) low levels of genetic differentiation among all recruit samples, and (2) the fact that the 4 documented parents occurred at only 2 sites. These findings empirically demonstrated the effectiveness of MPAs as useful conservation and management tools and highlighted the value of identifying both the sources and successful settlement sites of marine larvae. I next examined patterns of larval dispersal in bicolor damselfish (Stegastes partitus, Pomacentridae) collected during the summers of 2004 and 2005 from reefs lining the Exuma Sound, Bahamas (measuring 205 km by 85 km). Parentage analysis directly documented two parent-offspring pairs located within the two northern-most sites, which indicated self-recruitment at these sites. Multivariate analyses of pair-wise relatedness values confirmed that self-recruitment was common at all sampled populations. I also found evidence of “sweepstakes events”, whereby only a small proportion of mature adults contributed to subsequent generations. Independent sweepstakes events were indentified in both space and time, bolstering the direct observations of self-recruitment and suggesting a role for sweepstakes analyses to identify the scale of larval dispersal events. This dissertation provides insights into the patterns of larval dispersal in coral-reef fishes. The coupling of direct (e.g., parentage) and indirect (e.g., assignment methods, sweepstakes analyses) methods in conjunction with continued technological and methodological advances will soon provide large-scale, ecologically relevant, rates of larval exchange. By uncovering the dynamics of these enigmatic processes, the implementation of conservation and management strategies for marine fishes in general will undoubtedly experience greater success.
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2287. [Article] Snag longevity, bird use of cavities, and conifer response across three silvicultural treatments in the Oregon Coast Range
In the interest of meeting multiple forest management goals that include maintenance of wildlife, particularly cavity-nesting birds, uneven-aged silvicultural treatments are used increasingly in the Pacific ...Citation Citation
- Title:
- Snag longevity, bird use of cavities, and conifer response across three silvicultural treatments in the Oregon Coast Range
- Author:
- Walter, Scott T.
In the interest of meeting multiple forest management goals that include maintenance of wildlife, particularly cavity-nesting birds, uneven-aged silvicultural treatments are used increasingly in the Pacific Northwest. However, questions remain regarding the responses of cavity-nesting birds and residual green trees to different harvest intensities and patterns. To study these issues, between 1989 and 1991 the Oregon State University College of Forestry Integrated Research Project (CFIRP) applied 3 silvicultural treatments to 30 mature (85-125 year old) Douglas-fir stands in the Oregon Coast Range. Silvicultural treatments consisted of group-selection cuts (18 stands with 33% of the timber volume extracted from 0.2-0.6 ha patches), two-story regeneration harvests (6 stands with 75% scattered removal of the timber volume resulting in 20-3 0 distributed residual trees/ha), and clearcuts (6 stands that retained 1.2 mature green trees/ha). In addition, 939 conifers 53 cm diameter at breast height [DBH]) were topped to create snags in clustered and scattered arrangements. In the current study, CFIRP stands were utilized to 1) test for differences in cavity-nesting bird use of snags across silvicultural treatments and snag arrangements 10 years after harvest, 2) compare 10 year with 5 year nesting levels, 3) evaluate associations between snag characteristics and cavity nest site location, 4) quantify snag fall, 5) assess silvicultural treatment effects on residual tree growth and condition, and 6) quantify tree mortality. Snags and topped conifers that remain alive were observed for nesting and foraging use during the 2001 breeding season. Eight species of birds nested in created snags and a mean of 5.1 total cavities/snag were found one decade after creation. However, no active nesting was observed in topped trees that remained alive. Higher cavity-nesting bird levels, species richness, and species diversity occurred in open-canopy stands (two-story and clearcut treatments) compared to closed-canopy stands (group-selection treatment). Bird species composition was most similar between two-story and clearcut stands, and least similar between clearcut and group-selections stands. No difference was found in nesting or foraging levels between clustered and scattered snags. Active nests in created snags were most commonly located in the top 25% of bole, cavities on average faced northeast, and created snags with and without dead branches received equal nesting use. Compared with 6 years prior, the mean number of cavities per created snag increased 3.3- to 6-fold, and 4 additional avian species were observed nesting. One topped conifer fell in the decade since creation. Residual green trees (n = 848) were measured for growth and condition from November, 2001 to February, 2002. Across silvicultural treatments, residual green tree basal area, DBH, and height growth, and crown width and crown fullness did not differ among silvicultural treatments 10-12 years following harvest. Overall, 45% of trees experienced greater basal area growth in the decade following harvest than in the decade prior to harvest. Among silvicultural treatments, mean live crown ratio (live crown length/total tree height) of residual trees was significantly greater (0.74) in clearcuts and the percentage of trees with epicormic branching (35%) was significantly higher in two-story stands. Over the last decade residual tree mortality resulted in 134 standing dead trees (snags) and 185 blowdowns. Two-story stands experienced the highest recruitment of snags (0.76 per ha) and blowdowns (1.12 per ha). Results from this study suggest that topped, large conifers provide snags that offer valuable nesting and foraging habitat for cavity-nesting birds during the first decade after treatment, if the tree dies. Snags in both clustered and scattered arrangements appear to receive equal use by cavity-nesting birds. Also, snags created by topping may have the potential to stand for several decades in the Oregon Coast Range. Furthermore, although silvicultural treatments in this study did not appear to affect residual tree basal area growth during the first 10 years after treatment, partial harvests can promote increased diversity in stand structural complexity, which includes longer tree crowns, epicormic branching, and new snag recruitment, that also can benefit cavity-nesting bird populations through increased nesting and foraging opportunities.
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Coral reef ecosystems are the oceanic equivalent of tropical rainforests, in terms of biodiversity. The estimated 1,037,000 square kilometers worldwide of reef provide habitat for over one million species ...
Citation Citation
- Title:
- An evaluation of the likelihood of successful implementation of the long term coral reef monitoring program on the Commonwealth of the Northern Mariana Islands
- Author:
- Kylstra, Pam
Coral reef ecosystems are the oceanic equivalent of tropical rainforests, in terms of biodiversity. The estimated 1,037,000 square kilometers worldwide of reef provide habitat for over one million species of plants and animals (Hinrichsen, 1997). Coral reefs are important to the economy of coastal nations because of the fisheries and tourism industries they support. Reef ecosystems provide a host of important natural services such as storm buffering, a protein source for islanders, breeding and nursery grounds for marine organisms, water filtration and a source of biomedically important products. Coral reef areas also have aesthetic and intrinsic value that is reason enough to protect them. Coral reefs are also among the most endangered ecosystems on Earth. Naturally occurring disturbances are compounded by the impacts of anthropogenic disturbance. Factors that threaten the health of coral reef ecosystems on a global scale include global warming, the continuing increase in coastal populations and associated impacts such as nutrient pollution, sedimentation and runoff, coral mining, ship groundings, overfishing, and recreational overuse. Globally, coastal areas accommodate about 60% of Earth's human population. A significant portion of the population lies within tropical regions. This population pressure subjects coral reef environments to effects of increased competition for coastal resources, increased coastal pollution and problems related to coastal construction. The synergistic effect of stressors has been the irreversible degradation worldwide of 10% of reefs and another 60% in critical condition leaving, only 30% as stable (Wilkinson, 1993). The coral reefs of the Commonwealth of the Northern Mariana Islands (CNMI) are a good example of how the combination of increasing human population and the associated environmental pressure has resulted in degradation of the reef ecosystem. The CNMI has undergone significant change in economic and population growth within the past decade. To accommodate the rapid and continuing development of the tourism industry, numerous golf courses and resort hotels have been constructed on Saipan. The population of Saipan has increased over 30% in the last ten years. Currently, the local/resident population is 60,000 while the visitor population is 750,000 per year. This rapid growth has had serious ecological consequences. Coral roads have been converted to four lane highways and infrastructure such as septic tank systems has not been improved to meet higher demand. More and more development projects have been proposed without adequate consideration of environmental impacts. Conflicts over the use and conservation of marine and watershed resources continue to arise. The continuing decline of reef systems globally and in specific areas like the CNMI, highlights the need for effective methods of assessing change in nearshore ecosystems. This paper explores the ways that coral reef monitoring can provide information about reef health that serves to affect positive changes in management strategies for marine systems. Using a criteria drawn from case study comparisons of ongoing, well established coral monitoring programs and evaluation framework proposed by policy analysts Using criteria drawn from case, the Long Term Marine Monitoring Program (LTMMP) on Saipan, CNMI is evaluated. The evaluation provides insight about coral monitoring plan components that are essential to the effectiveness of coral reef monitoring programs. This report is an outgrowth of an internship the author performed with the CNMI Division of Environmental Quality on the island of Saipan from June to October of 1997. The University of Oregon Micronesia and South Pacific Program and the government of the Commonwealth of the Northern Mariana Islands (CMNI) sponsored the internship project. The objectives of the internship were to assist in field data collection and continuing development of the ongoing Long Term Marine Monitoring Plan (LTMMP) Assist and instruct Marine Monitoring Team (MMT) members in basic computer skills, understanding of data applicability, management, interpretation and analysis, basic biology and resource management techniques as it relates to marine monitoring work Facilitate inter-governmental agency coordination of marine monitoring activities Assess likelihood of success and explore challenges facing Saipan in implementation of the monitoring program This report first describes functions and services provided by coral reefs and an introduction to the stresses and disturbances that compromise the health of reef systems globally. Using examples from case studies of established marine monitoring programs, this report considers how effective monitoring can reveal changes in the reef system over time, enabling conservation measures to be taken. It then turns to the island of Saipan and briefly describes the environmental and socio-economic framework within which the coral reef related provisions of the CNMI coastal management program are considered. This background information is used to evaluate the Long Term Marine Monitoring Plan currently in place on the CNMI. This evaluation provides insight into the challenges to implementation of coral reef monitoring plans and recommendations for improvements in the LTMMP on Saipan.
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2289. [Article] The use of ơ15N and ơ¹³C to analyze food webs and identify source-sink relationships in riparian canopy vegetation of the Oregon Coast Range
In the Coast Range of western Oregon, some natural resource managers are converting red alder-dominated riparian areas to conifers to increase the future source of in-stream large wood for salmonid habitat. ...Citation Citation
- Title:
- The use of ơ15N and ơ¹³C to analyze food webs and identify source-sink relationships in riparian canopy vegetation of the Oregon Coast Range
- Author:
- Scott, Emily E.
In the Coast Range of western Oregon, some natural resource managers are converting red alder-dominated riparian areas to conifers to increase the future source of in-stream large wood for salmonid habitat. However, studies in Alaska have shown red alder-dominated riparian areas support greater invertebrate biomass compared to conifer-dominated areas. In addition, red alder can influence the nutrient dynamics of a site with N-rich litter inputs. Thus, these forest conversions have the potential to change riparian food webs and nutrient dynamics. The objectives of this thesis were to determine the utility of natural abundance stable isotopes of nitrogen and carbon in food web analyses and to describe nutrient dynamics and source-sink relationships in red alder- and Douglasfir- dominated riparian areas of the central Oregon Coast Range. We address three questions in this study: 1) What is the degree and source of δ15N and δ13C variation in foliage of Douglas-fir and red alder? 2) Are Douglas-fir and red alder isotope signatures sufficiently distinct to be used in food web analysis? and 3) Are there differences in nutrient dynamics and source-sink relationships between Douglasfir- and red alder-dominated riparian areas? To address these questions, we sampled foliage, litterfall, forest floor material, and soil from ten Douglas-fir- and red alder-dominated riparian sites as well as foliage from plantation Douglas-fir and red alder for δ15N, δ13C, and nutrient concentrations. Douglas-fir had greater variation in foliage δ15N within a tree crown, within a site, and among sites than red alder. Red alder had consistent foliage at all scales, near 1 .5%o, a value that is characteristic of nitrogen fixing species. Both species had similar levels of variation in foliage δ13C at all scales. Douglas-fir was slightly enriched in '3C compared to red alder suggesting greater water-use efficiency in Douglas-fir. Overall, the difference between δ15N and δ13C of red alder and Douglas-fir at our study sites were, on average, less than 2.O%o. It is unlikely stable isotopes could be used over broad geographic areas as a tool for determining the contributions of Douglas-fir versus red alder to food webs, although site-specific research may be possible where Douglas-fir and red alder demonstrate greater isotopic differences. Douglas-fir and red alder exhibited opposite source-sink relationships with soil for N exchange: Douglas-fir was a sink for soil N whereas red alder served as a N source. Douglas-fir sites had a higher N status and lower soil δ15N along the stream compared to upslope, trends not found at red alder sites. Soil δ15N near streams on Douglas-fir sites was similar to the soil δ15N on red alder sites suggesting that a legacy of past red alder along the stream may have contributed to the N status and soil δ15N gradients on Douglas-fir sites. Soil δ15N and soil δ15N did not indicate a presence of marine N on our sites. δ15N and δ13C of foliage and soil suggested decomposition processes of leaf litter differed between Douglas-fir and red alder, likely due to different lifter chemistries and possible influences on decomposition enzymes. A shift in species composition from red alder-dominated to Douglas-fir-dominated riparian areas would alter source-sink relationships with soil N and litter decomposition processes, although some legacies of soil enrichment in N by red alder would persist.
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2290. [Article] Population genetics of ranid frogs : investigating effective population size and gene flow
This dissertation focuses on the evolutionary forces of genetic drift and gene flow in frog populations. The balance of these two forces and the force of mutation largely determine the amount of neutral ...Citation Citation
- Title:
- Population genetics of ranid frogs : investigating effective population size and gene flow
- Author:
- Phillipsen, Ivan Clayton
This dissertation focuses on the evolutionary forces of genetic drift and gene flow in frog populations. The balance of these two forces and the force of mutation largely determine the amount of neutral genetic variation within populations as well as the degree of genetic similarity among populations. The stochastic evolutionary change caused by genetic drift can be quantified through the use of the effective population size (N[subscript e]) parameter. The effective size of a population is the number of breeding individuals in a conceptual, ideal population that would evolve by genetic drift at the same rate as the real population being studied. How a population responds to mutation, selection, and gene flow depends on N[subscript e], rather than the actual census population size (N). In most natural populations, N[subscript e] is considerably smaller than N. For these reasons, N[subscript e] is a fundamental parameter in basic population genetics theory as well as in applied conservation genetics. The degree of neutral genetic similarity between populations is highly dependent upon gene flow. When gene flow between a pair of populations is low, the populations are likely to become genetically differentiated. Conversely, when gene flow between populations is high, the populations will tend to be more genetically similar. Amphibians are good model organisms for studying genetic drift and gene flow because they tend to exhibit strong population structure at small spatial scales. This is a consequence of their generally small population sizes, natal philopatry, limited dispersal capabilities, and restricted habitat requirements. They are expected to have easily-detectable signatures of spatial genetic structure and genetic drift. Amphibians can be used as models to further our understanding of evolutionary processes and that understanding can be applied to the conservation of amphibians. Equipped with knowledge of what naturally influences genetic drift and gene flow in amphibians, we can apply the principles of population genetics to mitigate the genetic consequences of amphibian declines. In Chapters 2 and 3, I used molecular genetic data from frog populations to investigate N[subscript e] and the related parameter N[subscript b] (the effective number of breeders). Chapter 2 is a study of a single population of the Oregon spotted frog (Rana pretiosa). My aim was to determine where in the life cycle of this species the greatest reduction in N[subscript b] occurs. I used genetic data from microsatellites to estimate N[subscript b] at two different life stages, eggs and metamorphs, and found that estimates of N[subscript b] were similar at both stages. This result suggests that inflated variance in family size due to egg mass mortality is not a primary cause of N[subscript e] reductions relative to N in this species. Chapter 3 is a comparison of N[subscript e] estimates within and among four species of frogs in the family Ranidae: R. pretiosa, R. luteiventris, R. cascadae, and Lithobates pipiens. I obtained N[subscript e] estimates for 90 populations across the four species, using microsatellite data and several different estimators. The first three species and the western populations of L. pipiens have very small effective sizes (< 50). Eastern populations of L. pipiens are much larger, with N[subscript e] estimates in the hundreds and thousands. I also found significant correlations between N[subscript e] estimates and latitude, longitude, or altitude in R. luteiventris and L. pipiens. Chapter 4 is a study of gene flow among populations of the Cascades frog (Rana cascadae) in the Olympic Mountains of Washington. I quantified genetic differentiation among 22 R. cascadae populations with data from microsatellite markers and used a landscape genetics approach to identify environmental features that have strong influences on gene flow in this species. I used a Random Forests statistical procedure to assess which of several structural connectivity models and 15 landscape variables explained the most variation in genetic distances among populations. I found that the best-fitting Random Forests models were based on different structural connectivity models for two datasets: 'within' and 'between' genetic clusters of populations. The landscape variables identified as the most important also differed across the two datasets, suggesting that landscape influences vary across spatial scales. The results presented in this dissertation led to an increased understanding of effective population size in ranid frogs and of the environmental factors that influence population structure in R. cascadae. These studies provide a foundation for further research on the specific factors that influence genetic drift and gene flow in these species.
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Quaking aspen (Populus tremuloides Michx.) is known to be a widely distributed, shade-intolerant and short-lived hardwood found in both seral, even-aged and stable, uneven aged stands. There have been ...
Citation Citation
- Title:
- Influence of silvicultural treatments, overstory, and understory vegetation on quaking aspen (Populus tremuloides) regeneration in southeastern Idaho
- Author:
- Muñoz, Bethany L.
Quaking aspen (Populus tremuloides Michx.) is known to be a widely distributed, shade-intolerant and short-lived hardwood found in both seral, even-aged and stable, uneven aged stands. There have been reports of extensive aspen mortality, crown thinning, and branch dieback across North America that have been linked to the occurrence of severe droughts since 2001-2002. Because of reports of low aspen regeneration across the Intermountain West, as well as predictions of increases in aspen regeneration in the Northeastern US, researchers and land managers have now focused on managing aspen stands under the assumption that there are multiple aspen types. They have focused on improving resilience within quaking aspen stands with changing ecological conditions. For this thesis I focused on a project the Bureau of Land Management (BLM), Pocatello Field Office initiated in part to improve aspen restoration and resilience of stands in Soda Springs, ID. The BLM conducted two mechanical removal treatments: cut and pile, and slash/lop and scatter. In addition several sites were broadcast burned to reduce fuel loads and conifer density, to enhance aspen regeneration and improve aspen stand resilience. According to the Soda Springs Hills Fuels Reduction and Ecosystem Restoration Environmental Assessment (EA), the BLM aimed to meet the objective of 2500 quaking aspen suckers per ha (1000 suckers per ac) within the two years following treatment, an index of treatment adequacy. My primary objective for this thesis was to assess the influence of each silvicultural treatment, including the change in overstory and understory vegetation, on regeneration of aspen. Mean aspen regeneration two growing seasons after treatment was 11,532 suckers/ha on sites that received slash/lop and scatter treatment, followed by broadcast burning. With these high levels of suckering, there were also low densities of residual overstory conifers (≤ 4 trees/ha with a basal area ≤ 2 m²/ha). In comparison, sites that received the cut and pile treatment followed by a broadcast burn had a mean aspen regeneration of 44 suckers/ha, with higher densities of overstory conifers (≥ 32 trees/ha with a basal area ≥ 26 m²/ha). In slash/lop and scatter treatments without burning, sucker densities were as high as 1117 suckers/ha with low densities of conifers (0 trees/ha). In comparison, the site that received the cut and pile treatment without burning had an aspen regeneration of 0 suckers/ha, with a high density of conifers (36 trees/ha with a basal area of 47 m²/ha). Overall, sites with low residual overstory cover of large conifer trees (< 4 trees/ha), regardless of the treatment, had higher sucker densities two growing seasons after treatment (6244 suckers/ha, on average) than those seen in sites with a remnant overstory of >16 trees/ha (29 suckers/ha, on average). Also, sites that were burned, regardless of the mechanical treatment used, had higher sucker densities (11,244 suckers/ha) than those seen in sites that were not burned (576 suckers/ha). When comparing aspen sucker densities to competing understory woody cover following mechanical treatment, aspen sucker density was lowest (411 suckers/ha) on the site where both tree and shrub percent cover were highest (10 and 16%, respectively). Suckering appeared to be positively correlated with grass cover, however, with as high as 1117 suckers/ha growing with a high percentage of grass cover (≥ 26 %), on sites measured for change in understory following mechanical treatment. Results were collected on a small number of sites and thus have limited statistical significance. However, we are confident that observed trends have values for managers. We suggest that transects should continue to be monitored to observe the long-term effects of silvicultural treatments on overstory and understory vegetation, which are likely to be influenced by climate variability and other disturbances into the future.
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The Steller Sea Lion Research Initiative was passed in 2001 to provide funding to help scientists determine causes and solutions for the population crash of Steller sea lions (Eumetopias jubatus). In response ...
Citation Citation
- Title:
- Steller sea lions (Eumetopias jubatus) of Oregon and Northern California: seasonal haulout abundance patterns, movements of marked juveniles, and effects of hot-iron branding on apparent survival of pups at Rogue Reef
- Author:
- Scordino, Jonathan
The Steller Sea Lion Research Initiative was passed in 2001 to provide funding to help scientists determine causes and solutions for the population crash of Steller sea lions (Eumetopias jubatus). In response to need to understand population dynamics of Steller sea lions, NOAA Fisheries has spearheaded a large-scale, range-wide research program. The study involved capturing and hot-iron branding sea lions at rookeries from northern California around the Pacific Rim to Russia to provide individually recognizable animals for studies of behavior and vital rates. I report the results of monitoring pups branded and tagged at Rogue Reef, Oregon and St. George Reef, California to determine movement patterns and the affects of branding on apparent survival of Steller sea lion pups immediately after branding. Counts of Steller sea lion adult female, adult male, juveniles, and pups were collected at haulouts and rookeries of Oregon and northern California from 2002 through 2005. Movement patterns of Steller sea lions were inferred from count data. Adult males were seasonal inhabitants of Oregon and California during the breeding season from May through September before dispersing to northern feeding grounds. Females, juveniles, and pups were dispersed throughout haulouts in Oregon and northern California during all seasons but have seasonally high concentrations at Sea Lion Caves, Oregon in the winter and at the breeding rookeries during the summer breeding season. The high wintertime abundance of females and pups at Sea Lion Caves suggests that it should be considered as critical habitat for Steller sea lions of the eastern stock. Resights of marked sea lions collected between northern California and Alaska between 2001 and 2005 were analyzed to determine juvenile and pup dispersal patterns. Most pups stay close to their natal rookery, although 9 - 22% of individuals each year were observed to disperse further than 500 km. As 1-year olds, the mean maximum dispersal range expanded, which may have been a sign of weaning. Sexually dimorphic patterns in sea lion movements were apparent at 3 years of age as males were observed to disperse farther north than females. The percentage of females observed at their natal rookery increased each year to a maximum of 87% as 4-year-olds. This suggested that sexual maturity occurs at, or close to, 4 years of age for females. Branding provided a useful tool for analyzing movements of Steller sea lions, yet it may have impacts on survival of individuals. Concerns raised by NOAA Fisheries over branding impacts on pup survival were addressed with a study at Rogue Reef in 2005. One-hundred-and-sixty pups captured on 18 July, 2005 were randomly assigned to a treatment of flipper tag only (unbranded pups) or flipper tag and hot-iron branding (branded pups). Aside from the treatment of branding, all pups were handled and treated identically. Over the 73-day course of this study, I found lower apparent survival for branded pups than unbranded pups, with a final apparent survivorships of 0.23 (95% CI 0.01 – 0.48) for branded pups and 0.46 (95% CI 0.15 – 0.77) for unbranded pups. Apparent survivorship includes both mortality and emigration, so differences may be due to differences in emigration rates of the two groups, mortality rates, or both. The scope of inference for this study is only to Rogue Reef in 2005. However, it should provide a good model for future brand evaluation studies at other rookeries and for other pinniped species. Branding is currently the best and only available tool for long-term studies of survival, reproduction rates, and age at sexual maturity which are all critical for demographic models. Nonetheless, researchers should assess the impacts of branding at each rookery, and will need to consider whether knowledge from branding Steller sea lions is worth the potential reduction in pup survival or change in pup emigration behavior observed in this study.
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Pacific Northwest prairies have become significantly reduced in extent, and in the Willamette Valley of Oregon, less than one percent of native upland prairies remain. Many species have been impacted by ...
Citation Citation
- Title:
- Responses of Pacific Northwest prairies to soil nutrient manipulations : implications for restoration of Castilleja levisecta and control of invasive species
- Author:
- Lawrence, Caitlin Elizabeth
Pacific Northwest prairies have become significantly reduced in extent, and in the Willamette Valley of Oregon, less than one percent of native upland prairies remain. Many species have been impacted by this extreme loss of habitat, including Castilleja levisecta (golden paintbrush), a threatened hemiparasitic forb species endemic to the Pacific Northwest. Many of the prairie fragments that remain are poor quality, and face the threat of invasion from non-native species and a loss of biodiversity. These non-native species pose an obstacle to restoration and to the reintroduction of threatened and endangered species. Nutrient enrichment has been shown to promote increased invasion of communities, decrease success of native species, and decrease biodiversity. A way to counter these effects is through carbon addition to the soil which stimulates microbial activity and immobilizes nutrients, making them unavailable to plants. This strategy has potential as a restoration tool to improve conditions for native species, which are often outcompeted under high nutrient conditions. We tested the efficacy of carbon addition for controlling non-native species and restoring C. levisecta in two Willamette Valley prairies. We created treatments of varying nutrient availability and measured the responses of the plant community and of C. levisecta. Experimental plots were established in autumn 2012 with either carbon (sucrose) addition, ambient soil nutrients (controls), or nutrient addition (NPK fertilizer). Nutrient treatments were reapplied throughout the length of the experiment. Crossed with these treatments in a fully factorial design were seeding treatments of C. levisecta and of thirteen other native species, to increase the diversity of the plant community, providing host plants for C. levisecta, a hemiparasitic plant. In the two growing seasons following treatment we conducted plant community surveys and counted and measured seedlings of C. levisecta to determine the effects of the nutrient manipulations and seeding treatments on the community overall and on this threatened plant. Community composition differed significantly between the different nutrient treatments (perMANOVA, p<0.001) at both study sites, and in both years of the experiment. Mean total vascular plant cover was significantly reduced by carbon addition compared to ambient nutrient availability, and increased by nutrient addition. Native grasses were unaffected by nutrient manipulation at either site, whereas non-native grasses were greatly reduced by carbon addition and increased by nutrient addition, compared to ambient soil nutrient availability. Non-native forbs were also greatly reduced by carbon addition, and were also reduced by nutrient addition by the second year of the experiment. Richness of non-native species was more affected by nutrient manipulation than richness of natives, and was either increased or unaffected by nutrient enrichment and decreased by carbon addition. Some non-native species were found to be highly affected by the nutrient manipulation, while others were not, suggesting that carbon addition may be an effective control for only certain non-native species. At both sites, C. levisecta emergence was lower in carbon addition plots compared with controls. In nutrient addition plots, C. levisecta emergence was higher at one site but lower at the other compared with controls, suggesting that nutrient addition may be beneficial only under certain conditions. Additionally, by the second year of the experiment, there was no difference in C. levisecta numbers between the control and nutrient addition plots at one site, and there were fewer in the nutrient addition plots than in controls at the other site. The seeding of additional native species increased community richness but had little effect on diversity and no effect on C. levisecta establishment. Overall, these results suggest that nutrient enrichment can promote the success of non-native species and that carbon addition can be used to counter these effects on a species- and site-specific basis. However, carbon addition did not improve reintroduction success of a threatened plant species, C. levisecta, and the effects of nutrient addition on its success after two years were mixed.
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2294. [Article] The ecology and production dynamics of four black fly species (Diptera:simuliidae) in western Oregon streams
Ecological and production studies of Prosimulium caudatum Shewell, P. dicum Dyar and Shannon, Simulium arcticum Malloch and S. canadense Hearle (Diptera: Simuliidae) were made in 1971 and 1972 in three ...Citation Citation
- Title:
- The ecology and production dynamics of four black fly species (Diptera:simuliidae) in western Oregon streams
- Author:
- Speir, Jon A.
Ecological and production studies of Prosimulium caudatum Shewell, P. dicum Dyar and Shannon, Simulium arcticum Malloch and S. canadense Hearle (Diptera: Simuliidae) were made in 1971 and 1972 in three streams near Corvallis, Oregon. The purpose of the study was to characterize the biology and population dynamics of larvae, and to compare the production of the four species under various spatial and temporal conditions. A total of 54 annual production estimates was derived utilizing 37 stations. In addition, 17 annual drift and 22 emergence (as pupae) determinations were made. Data on the physical and chemical characteristics of the streams, and on larval associates, parasites, predators and food types were obtained at all stations. Laboratory experiments provided data on feeding rates and predator impact. The two Prosimulium species always coexisted, and occurred in all streams. Simulium arcticum and S. canadense were studied in two streams only. All species were univoltine and had egg stage durations exceeding 40 weeks. Prosimulium spp. larvae appeared in mid-February and were on riffles for an average of 10.3 weeks. Simulium arcticum hatching began about six weeks later. Larvae of this species developed in an average of 8.8 weeks. Development of S. canadense began about nine weeks later than for Prosimulium spp. but lasted nearly as long. All four black flies had six larval instars. All larvae were filter feeders, and fed primarily on the suspended materials in the streams. Detritus made up from 65-90% of the diet, with the rest being filamentous algae. Alimentary tract clearing of larvae was usually accomplished in less than one hour. Black fly immatures were associated with about 75 other benthic insect species. Of these, nine were likely important simuliid natural enemies. Fish were minor black fly predators. Gastromermis nematodes occurred in about 3% of all mature simuliid larvae. Annual losses due to drift averaged about 6%. Simuliid drift appeared to be a function of standing crop density. Growth-related crowding may also have been a factor. Effects of diel light conditions, temperature and discharge were minimal. A diel emergence pattern existed for Simulium spp. adults only. The time between emergence and oviposition was likely about 0.5 week for all species. Emergence at most stations was single peaked, and averaged 3. 6 weeks in duration. The sampling universe at each station could be effectively partitioned to exclude areas where larvae did not exist. Thus, the weekly stratified random sampling program provided population estimates with error terms of usually 15% or less. All quantitative data were expressed on a per m² of overall riffle basis (and not on a per m² of habitat basis) to make the study more comparable to other benthic research. Density, biomass and production differences between stations, streams and years were minimal for each species, and therefore were treated as replicates. Initial densities ranged from over 11000 to about 16000 larvae/m². Mortality for aggregates of all species was similar, with about 70% of all losses occurring during the first half of larval life. Growth for all species was generally logistic and averaged over 0.090 gig per day annually. Production, averaged for 1971 and 1972, in g/m² , was: P. caudatum, 2.644; P. dicum, 2.908; S. canadense, 3. 141; and S. arcticum, 3.950. This species ranking also held for initial density, mean density and mean biomass. Biomass and production were almost always closely correlated. Mortality variations had a greater influence on production than did growth rate. Averaged for all species, the mean total mortality due to drift and parasites was 6.2% and 0.5% respectively. An average of 10.7% of colonizing larvae survived to emerge. Predator-caused losses were estimated to provide the 82.6% needed to balance the loss budget. Black fly larvae were the dominant processor of suspended materials in the three streams. On the average, they outnumbered all other primary consumers combined on riffles by a factor of 27. Simuliid larvae functioned as the primary prey reservoir for as many as 20 species of insect carnivores from February through June of both years.
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2295. [Article] Systematics of the salamander genus Dicamptodon strauch (Amphibia:Caudata:Ambystomatidae)
Dicamptodon is the single, extant genus of the ambystomatid subfamily Dicamptodontinae. Two species, D. ensatus (Eschscholtz) and D. copei Nussbaum are recognized. D. ensatus is found in the forested, ...Citation Citation
- Title:
- Systematics of the salamander genus Dicamptodon strauch (Amphibia:Caudata:Ambystomatidae)
- Author:
- Nussbaum, Ronald A.
Dicamptodon is the single, extant genus of the ambystomatid subfamily Dicamptodontinae. Two species, D. ensatus (Eschscholtz) and D. copei Nussbaum are recognized. D. ensatus is found in the forested, mountain regions of northwestern California and western Oregon, in the Willapa Hills and Cascade Mountains of Washington, in extreme southwestern British Columbia, and in the northern and central Rocky Mountains of Idaho. D. copei is found in the Olympic Mountains, Willapa Hills and southwestern Cascades of Washington; and in the vicinity of the Columbia River Gorge in extreme northwestern Oregon. The two species are sympatric in the Columbia River Gorge, southern Willapa Hills, and southwestern Cascades of Washington. The two species differ, among other characters, in blood serum proteins, sensitivity to thyroxine, mode of life history, body size, relative head size, limb length, tail height, tooth number, gill raker number, color, and degree of ossification of skeletal elements. Geographic variation is prominent in D. ensatus. Multivariate analysis of morphometric characters of larval populations discriminates three groups: a Rocky Mountain Group, a Cascade and Oregon Coast Range Group, and a Californian Group. The first two groups seem to be more similar to each other than either is to the Californian Group. The Californian Group can be divided into a southern subgroup and a northern subgroup; and the northern subgroup can be further separated into a coastal subgroup and an interior highlands subgroup. These groups are all more-or-less verified by analysis of color of larvae and adults, and morphometric characters of adults. These groups correspond geographically with major features of topography in the Pacific Northwest. The California Group is confined south of the geologically old and complex Klamath-Siskiyou Mountains. The southern Californian subgroup is found south of the "North Coast Divide", and the northern subgroup is found north of this Divide in an area of northwestern drainage. The interior highlands subgroup of the northern Californian subgroup is found in the higher, summer-dry mountains of northern California where the substrate is complex and of a different origin than the coastal substrate. Strong morphoclines occur across the Klamath-Siskiyou Region into southwestern Oregon. The Rocky Mountain Group is separated from the Cascade and Oregon Coast Range Group by the broad, arid Columbia Plateau. Variation is slight over the relatively small range of D. copei, and what variation exists seems to be a function of geographic distance. The dicamptodontines have been an evolutionarily conservative group confined to the humid temperate, Arcto-Tertiary environments of western North America throughout their Cretaceous and Tertiary history. A remnant of the once wide-spread, ancestral habitat occurs today in the humid fog belt of northwestern California and southwestern Oregon. D. ensatus living in this area today exhibit the most primitive features of all living Dicamptodon. These include: large heads, long limbs and tails, many teeth and gill rakers, propensity to transform, and perhaps the habit of vocalizing as a terrestrial, defensive adaptation. D. copei is viewed as a relatively recent derivitive of an ensatus-like ancestor. This ancestor is believed to have had a propensity for neoteny and body attenuation associated with life in the extreme climatic, physical, and biotic environments imposed by Pleistocene glaciation. Isolation in western Washington during a glacial maximum allowed these tendencies, along with small body size, to be selected for, unhampered by gene flow from outside populations. It is thought that the ensatus-like ancestor of D. copei was more similar to recent northern populations of D. ensatus than to recent Californian populations of D. ensatus. Californian populations were relatively unaffected by Pleistocene climatic extremes, as they passed this period in the milder, ancestral environment of southern, coastal latitudes. During the last glacial maximum, the Rocky Mountain populations were probably continuous with populations on the lower eastern slopes of the Washington Cascades, via a connecting, wet, forested parkland, which existed south of the Cordilleran ice sheet in north-central Washington. This parkland was broken up after the ice retreated, during the Altithermal interval, about 7-4,000 years ago, and it was at this time that the Rocky Mountain Group became isolated. Postglacial readjustments in the ranges of D. copei and D. ensatus account for their current narrow zone of sympatry. Subspecies of D. ensatus and D. copei are not recognized.
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2296. [Article] Spatial Association of Humpback Whales (Megaptera novaeangliae) and their Prey in the Southern Gulf of Maine, USA
Efficient foraging strategies result in a predator spatially overlapping with its prey, foraging in the most profitable patches, and minimizing the time transiting between patches. Previous studies investigating ...Citation Citation
- Title:
- Spatial Association of Humpback Whales (Megaptera novaeangliae) and their Prey in the Southern Gulf of Maine, USA
- Author:
- Kirchner, Theresa
Efficient foraging strategies result in a predator spatially overlapping with its prey, foraging in the most profitable patches, and minimizing the time transiting between patches. Previous studies investigating baleen whale foraging strategies have generally focused on investigating spatial overlap with prey patches, patch profitability or movement within feeding grounds. The present study investigated the fine-scale strategies of movement between individual prey schools and larger prey patches in humpback whales (Megaptera novaeangliae) bubble-feeding on sand lance (Ammodytes spp.) in and around the Stellwagen Bank National Marine Sanctuary, USA. The goal was to investigate the presence of hierarchically nested spatial structures in both sand lance patches and whale bubble-feeding behavior, and to compare the scales and geometry of these patches between predator and prey behavior on each hierarchical scale. Furthermore, the profitability of sand lance schools in feeding areas was investigated. Using animal-borne tag technology to record underwater movement of whales in combination with surface observations of whale behavior, the locations of bubble-feeding events were identified. Concurrent hydroacoustic measurements of the prey distribution in the water column were used to identify the locations and energetic parameters of sand lance schools around tagged whales. First Passage Time analysis was used to determine the spatial scale of individual bubble-feeding events. Based on spatial proximity, feeding events and prey schools were grouped into larger feeding bouts and prey patches to investigate the presence of hierarchically nested scales. Up to three hierarchy levels were found in bubble-feeding behavior of nine whales tagged on six days between 2008 and 2012, and up to five hierarchy levels in the sand lance prey field around the tagged whales. There was a significant positive correlation between the lengths of whale bubble-feeding bouts and the lengths of sand lance patches over three common hierarchy levels. On each hierarchy level, the lengths of whale bubble-feeding bouts were significantly smaller than those of sand lance patches. Mean inter-feeding bout distances were significantly positively correlated with mean inter-prey patch distances over two hierarchy levels. Mean distances between feeding events were similar to the mean distances between prey schools. On larger hierarchy levels, mean inter-bout distances were greater than mean distances among prey patches. Mean school height and density tended to be greater in schools recorded inside than outside of feeding bout areas. The prey field structures found here were likely a result of the specific habitat requirements of sand lance. The results of this study suggest that the tagged whales were able to adapt their foraging movement to the structure of the prey field. By feeding on neighboring schools, whales could minimize the time spent between prey schools. On larger spatial scales, whales did not feed on neighboring prey patches. This could be a result of decreased abilities to find the nearest patch, or because, rather than restricting their foraging movement to neighboring patches, the whales were targeting specific patches. The foraging movement observed in this study led to spatial overlap of the tagged whales with sand lance schools that were characterized by properties rendering them more energetically profitable for bubble-feeding whales. While hierarchically structured foraging movement has been found in other marine predators, this is the first study that demonstrates this kind of foraging mechanism for baleen whales.
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2297. [Article] The influence of biophysical feedbacks and species interactions on grass invasions and coastal dune morphology in the Pacific Northwest, USA
Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially ...Citation Citation
- Title:
- The influence of biophysical feedbacks and species interactions on grass invasions and coastal dune morphology in the Pacific Northwest, USA
- Author:
- Zarnetske, Phoebe Lehmann, 1979-
Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially alter physical features in an environment, and this can lead to cascading effects on the biological community. Aquatic-terrestrial interface ecosystems are excellent systems to study the interactions among invasive ecosystem engineers, physical features, and biological communities, because interactions among vegetation, sediment, and fluids within biophysical feedbacks create and modify distinct physical features. Further, these systems provide important ecosystem services including coastal protection afforded by their natural features. In this dissertation, I investigate the interactions and feedbacks among sand-binding beach grass species (a native, Elymus mollis (Trin.), and two non-natives, Ammophila arenaria (L.) Link and A. breviligulata Fernald), sediment supply, and dune shape along the U.S. Pacific Northwest coast. Dunes dominated by A. arenaria tend to be taller and narrower compared to the shorter, wider dunes dominated by A. breviligulata. These patterns suggest an ecological control on dune shape, and thus, coastal vulnerability to overtopping waves. I investigate the causes and consequences of these patterns with experiments, field observations, and modeling. Specifically, I investigate the relative roles of vegetation and sediment supply in shaping coastal dunes over inter-annual and multi-decadal time scales (Chapter 2), characterize a biophysical feedback between beach grass species growth habit and sediment supply (Chapter 3), uncover the mechanisms leading to beach grass coexistence and whether A. breviligulata can invade and dominate new sections of coastline (Chapter 4), and examine the non-target effects resulting from management actions that remove Ammophila for the recovery of the threatened Western Snowy plover (Charadrius alexandrinus nivosus) (Chapter 5). I found that vegetation and sediment supply play important roles in dune shape changes across inter-annual and multi-decadal time scales (Chapter 2). I determined that a biophysical feedback between the beach grass growth habits and sediment supply results in species-specific differences in sand capture ability, and thus, is a likely explanation for differences in dune shape (Chapter 3). I found that all three beach grass species can coexist across different sediment deposition rates, and that this coexistence is largely mediated by positive direct and indirect species interactions. I further determined that A. breviligulata is capable of invading and dominating the beach grass community in regions where it is currently absent (Chapter 4). Combined, these findings indicate that A. breviligulata is an inferior dune building species as compared to A. arenaria, and suggest that in combination with sediment supply gradients, these species differences ultimately lead to differences in dune shape. Potential further invasions of A. breviligulata into southern regions of the Pacific Northwest may diminish the coastal protection ability of dunes currently dominated by A. arenaria, but this effect could be moderated by the predicted near co-dominance of A. arenaria in these lower sediment supply conditions. Finally, I found that the techniques used to remove Ammophila for plover recovery have unintended consequences for the native and endemic dune plant communities, and disrupt the natural disturbance regime of shifting sand. A whole-ecosystem restoration focus would be an improvement over the target-species approach, as it would promote the return of the natural disturbance regime, which in turn, would help recover the native biological community. The findings from this dissertation research provide a robust knowledge base that can guide further investigations of biological and physical changes to the coastal dunes, can help improve the management of dune ecosystem services and the restoration of native communities, and can help anticipate the impacts of future beach grass invasions and climate change induced changes to the coast.
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2298. [Article] Nearshore distribution of barnacle and mussel larvae and oceanographic mechanisms of onshore transport and delivery
Recruitment of larvae from the plankton is an important determinant of community structure in marine systems. In populations of many marine species, recruitment determines the basic demographic parameters ...Citation Citation
- Title:
- Nearshore distribution of barnacle and mussel larvae and oceanographic mechanisms of onshore transport and delivery
- Author:
- Tyburczy, Joe
Recruitment of larvae from the plankton is an important determinant of community structure in marine systems. In populations of many marine species, recruitment determines the basic demographic parameters of immigration, emigration, and reproduction. Moreover, the effect of recruitment as an "ecological subsidy" can determine the strength of interactions among species and whether populations are limited by recruitment itself, or by competition or predation. For this reason, understanding the transport of larvae is essential for management and conservation. In Chapter 2, my coauthors and I investigated the vertical and cross-shelf distribution of barnacle and bivalve larvae with a series of paired day/night sampling cruises off the coast of central Chile. Barnacle larvae were generally found close to shore (within 1.5 km), and the cross-shelf distribution of all taxa varied little despite contrasting upwelling conditions. Since current velocities decrease quickly with proximity to shore, larvae distributed in the nearshore are less likely to be dispersed long distances. Further, the consistent cross-shelf distribution of larvae suggests that they are not necessarily swept on- or offshore by upwelling or relaxation. Depth distributions consistent with classical diel vertical migration (DVM; swimming deeper during the day, shallower at night) were found in barnacle nauplii, but not barnacle cyprids or in bivalve larvae. One potential advantage of DVM is that it may limit offshore transport and thereby increase the odds that larvae will reach suitable habitat when they are competent to settle. Another possible benefit of DVM is that it may increase feeding opportunity in shallow water at night when visual predation risk is low, while providing refuge at depth during the day when visual predation in the upper water column is greater. In Chapter 3, my coauthors and I undertook a large-scale study in northern Monterey Bay, CA that integrated high-frequency physical and biological sampling to allow resolution of multiple different potential mechanisms of onshore larval transport and settlement. Depending on location within Monterey Bay, three processes were found to be associated with onshore barnacle settlement: regional upwelling, local diurnal upwelling driven by afternoon sea breezes, and the passage of an upwelling shadow front. Based on these findings we propose a novel conceptual model that encompasses oceanographic processes at multiple scales and reconciles apparent inconsistencies between empirical results and existing theories. In Chaper 4, my coauthors and I developed a simple larval transport model using data on currents, offshore flux of barnacle larvae, and onshore settlement of barnacles from the empirical study in Chapter 3. A parameter set was found that produced model settlement correlated with observed settlement. The fit of modeled and observed settlement was sensitive to model parameters. However, for all parameter sets examined, onshore transport of particles was much greater at depth. This result from the larval transport model is consistent with the conceptual model proposed in Chapter 3. Further, during intervals when onshore transport was observed, model particle trajectories clearly show onshore transport only at depth via two of the mechanisms identified in Chapter 3 (local diurnal upwelling and passage of the upwelling shadow front).
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2299. [Article] Rheological and spectroscopic characterization of surimi under various comminuting and heating conditions
Optimization of comminuting and heating conditions for surimi gel preparation obtained from three fish species: Alaska pollock (AP) (Theragra chalcogramma), Pacific whiting (PW) (Merluccius productus), ...Citation Citation
- Title:
- Rheological and spectroscopic characterization of surimi under various comminuting and heating conditions
- Author:
- Poowakanjana, Samanan
Optimization of comminuting and heating conditions for surimi gel preparation obtained from three fish species: Alaska pollock (AP) (Theragra chalcogramma), Pacific whiting (PW) (Merluccius productus), and threadfin bream (TB) (Nemipterus spp.) was the focus of this study. Three parameters during comminution were separately evaluated: chopping time, chopping temperature, and salting time. Results from fracture gel analysis suggested a strong relation between the fish's environmental habitat and optimal final chopping temperature. Extending chopping time to 15 min under strictly controlled temperature at 0 °C was preferable for cold water fish AP surimi. Even though high chopping temperature (20 °C) for a shorter time (12 min) surprisingly resulted in strong gel texture similar to that of 0 °C for 15 min, high chopping temperature should not be employed for AP surimi. AP could set as a gel at this temperature within a shorter time in a holding tank which could subsequently cause a problem when extruded on the cooking belt. Temperate water fish Pacific whiting, demonstrated its maximum gel strength when chopped at 15-20 °C. The optimum comminution condition for warm water fish threadfin bream surimi was to chop the surimi until the paste temperature reached between 25-30 °C. Prolongation of chopping once the surimi hit its threshold (optimum) temperature diminished the quality of the resulting protein gel. Cooling system connected to the chopping bowl is strongly recommended as it will allow the comminution process to be extended as long as possible until the surimi paste reaches its target temperature. Raman spectroscopy disclosed the different level of protein unfolding based on secondary structure of α-helix and β-sheet during various comminuting conditions. Unfolding of protein was facilitated by increased chopping temperature to a greater degree than extended chopping time. Extending chopping could denature the light meromyosin structure as it could not form a semi gel-like structure at temperatures between 32-40 °C. Protein solubility of surimi paste in salt solution always decreased with prolonged chopping time. The decrease rate accelerated with increased chopping temperature. The formation of disulfide interchange gradually took place during chopping as observed from Raman spectroscopy. Also the surface hydrophobicity increased with extended chopping time. However, gel strength behaved differently according to the various chopping conditions indicating the lack of its relationship between salt soluble protein, disulfide formation, and surface hydrophobicity to gel strength. During extending chopping time, not only more mechanical force is applied to unfold protein structure, but proteins also have longer time to be extracted more by salt. Addition of salt at a different time during chopping process was therefore conducted using threadfin bream surimi due to its higher thermostability. Extending chopping time without salt followed by salt addition at the last step resulted in lower gel texture compared to the conventional chopping protocol where salt is always added at the early stage of comminution. Mechanical chopping could unfold protein structure; however, proteins, rather than staying solubilized, would precipitate and form a randomized structure under the chopping condition without salt. The heating condition greatly affected the gelation and rheological properties of AP surimi. The highest elastic modulus was obtained with the slowest heating rate at 1 °C/min. Increased heating rate did not only shorten the time for proteins to unfold and form a well-organized network, it also interfered with the protein network through the vibration of water molecules as phase angle increased. This suggested that AP surimi gained more viscous properties and failed to form an elastic gel. Adjusting moisture content along with applying various frequencies did not alter the pattern of G' formation when paste was heated at different heating rates. AP surimi favored the slow heating.
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2300. [Article] Science basis for changing forest structure to modify wildfire behavior and severity
Fire, other disturbances, physical setting, weather, and climate shape the structure and function of forests throughout the Western United States. More than 80 years of fire research have shown that physical ...Citation Citation
- Title:
- Science basis for changing forest structure to modify wildfire behavior and severity
- Author:
- Graham, Russell T., McCaffrey, Sarah, Jain, Theresa B.
Fire, other disturbances, physical setting, weather, and climate shape the structure and function of forests throughout the Western United States. More than 80 years of fire research have shown that physical setting, fuels, and weather combine to determine wildfire intensity (the rate at which it consumes fuel) and severity (the effect fire has on vegetation, soils, buildings, watersheds, and so forth). Millions of acres of forestlands (mainly in dry forests dominated by ponderosa pine and/or Douglas-fir) contain a high accumulation of flammable fuels compared to conditions prior to the 20th century. Forests with high stem density and fuel loading combined with extreme fire weather conditions have led to severe and large wildfires (such as those seen in the summers of 2000, 2002, and 2003) that have put a number of important values at risk. Although homes in the path of a wildfire are perhaps the most immediately recognized value, these wildfires also put numerous other human and ecological values at risk, such as power grids, drinking water supplies, firefighter safety, critical habitat, soil productivity, and air quality. For a given set of weather conditions, fire behavior is strongly influenced by stand and fuel structure. Crown fires in the dry forest types represent an increasing challenge for fire management as well as a general threat to the ecology of these forests and the closely associated human values. Crown fires are dependent on the sequence of available fuels starting from the ground surface to the canopy. Limiting crown fire in these forests can be accomplished by actions that manage in concert the surface, ladder, and crown fuels. Reducing crown fire and wildland fire growth across landscapes decreases the chances of developing large wildfires that affect human values adjacent to forested areas. However, a narrow focus on minimizing crown fire potential will not necessarily reduce the damage to homes and ecosystems when fires do occur. Homes are often ignited by embers flying far from the fire front, and by surface fires. Fire effects on ecosystems can also occur during surface fires where surface and understory fuels and deep organic layers are sufficient to generate high temperatures for long periods. Fuel treatments can help produce forest structures and fuel characteristics that then reduce the likelihood that wildfires will cause large, rapid changes in biophysical conditions. Fuel treatments can also help modify fire behavior sufficiently so that some wildfires can be suppressed more easily. Subsequent, sustained fuel treatments can maintain these conditions. Different fuel reduction methods target different components of the fuel bed. Thinning mainly affects standing vegetation, and other types of fuel treatments such as prescribed fire and pile burning woody fuels are needed to modify the combustion environment of surface fuels. In forests that have not experienced fire for many decades, multiple fuel treatments—that is, thinning and surface fuel reduction—may be required to significantly affect crown fire and surface fire hazard. Fuel treatments cannot guarantee benign fire behavior but can reduce the probability that extreme fire behavior will occur. Fuel treatments can be designed to restore forest conditions to a more resilient and resistant condition than now exists in many forests, and subsequent management could maintain these conditions, particularly in dry forests (ponderosa pine and Douglas-fir) where crown fires were historically infrequent. The degree of risk reduction will depend to some degree on the level of investment, social and economic acceptability of treatments, and concurrent consideration of other resource values (for example, wildlife). This report describes the kinds, quality, amount, and gaps of scientific knowledge for making informed decisions on fuel treatments used to modify wildfire behavior and effects in dry forests of the interior Western United States (especially forests dominated by ponderosa pine and Douglas-fir). A review of scientific principles and applications relevant to fuel treatment primarily for the dry forests is provided for the following topics: fuels, fire hazard, fire behavior, fire effects, forest structure, treatment effects and longevity, landscape fuel patterns, and scientific tools useful for management and planning.