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In 1986, researchers from Oregon State University, led by Dr. David Brauner, came to the small Catholic community of St. Paul, Oregon as part of ongoing research on the French-Canadian inhabitants of the ...
Citation Citation
- Title:
- Women of valor : the Sisters of Notre Dame de Namur, St. Paul, Oregon, 1844-1852
- Author:
- Poet, Rebecca McClelland
In 1986, researchers from Oregon State University, led by Dr. David Brauner, came to the small Catholic community of St. Paul, Oregon as part of ongoing research on the French-Canadian inhabitants of the Willamette Valley between 1829 and the mid-1860s. They were searching for the remains of the first Catholic Mission in the Pacific Northwest. What they found was a cellar belonging to nuns who ran a boarding school for the daughters of the French-Canadians between 1844 and 1852. These women were upper-middle class Belgians belonging to the Sisters of Notre Dame de Namur order. The purpose of this research was to examine the archaeological data recovered from this project to see whether this novel situation was recognizable in the archaeological record. Secondly the objective was to intensively review the written record to determine details regarding the daily lives of these women. The final objective was to see what the combination of literature and archaeology can reveal about the texture of their lives. The research was divided into three phases: field archaeology, literature search, and artifact analysis. Field archaeology was accomplished over two field seasons and included pedestrian survey and surface collection and test pit and block excavation. Artifact analysis was loosely structured on a functional classification developed by Roderick Sprague. Artifacts were broken into three study units: block excavation, surface collection, and test pit excavation. Six Sisters of Notre Dame de Namur set foot on the shores of the Oregon Territory on August 1, 1844. They were the first Catholic nuns to come to the Pacific Northwest. Coming at the invitation of Father Francis Norbert Blanchet, they set up a boarding school for the daughters of the retired French-Canadian fur trappers who had settled in the Willamette Valley. Their school was in the small Catholic community of St. Paul. During their short stay in St. Paul they taught school while learning to survive. They developed skills such as bread-making, clothes washing, carpentry, livestock husbandry, and gardening. They left the Willamette Valley in 1852 and moved to San Jose in California where they established a college. The written record shows that the site where the Sisters lived served a dual function as a religious and educational facility and as a homestead. Archaeological evidence exists for the educational facility and homestead, but the religious aspect of the site was not apparent. The historical record shows that the inhabitants of the site were unique individuals within the location of French Prairie. The archaeology supports this, but does not definitively indicate gender, class, or ethnicity.
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372. [Article] The effect of precipitation variation on soil moisture, soil nitrogen, nitrogen response and winter wheat yields in eastern Oregon
The semi-arid regions of the Pacific Northwest are characterized by a high degree of annual temperature and precipitation variation. As a result of this climatic variation, dryland nitrogen fertilizer ...Citation Citation
- Title:
- The effect of precipitation variation on soil moisture, soil nitrogen, nitrogen response and winter wheat yields in eastern Oregon
- Author:
- Glenn, D. M. (David Michael)
The semi-arid regions of the Pacific Northwest are characterized by a high degree of annual temperature and precipitation variation. As a result of this climatic variation, dryland nitrogen fertilizer trials on fallow- ,wheat rotations typically demonstrate a variable response. Wheat growers in the area must not only cope with this climatic variation and its sundry effects upon their livelihood, they must also make decisions regarding the future level of anticipated climatic variation. The specific objectives were to: 1) develop a climatically responsive yield potential prediction model for soft white winter wheat from historical data at the Sherman Branch Experiment Station (Moro, OR); 2) modify this model for use on commercial fields; 3) field simulate five fallow-crop precipitation patterns characteristic of the variation found in the Sherman county area of eastern Oregon in order to test the yield potential model: 4) examine the effects of precipitation variation on nitrogen fertilizer responses, moisture storage and depletion and nitrogen mineralization; and 5) establish a quantitative relationship between precipitation/ soil moisture and nitrate accumulation in both the fallow and crop seasons. Two interacting regression models were developed to estimate grain yield levels in the 250-350 mm precipitation zone of eastern Oregon. The first model estimates yield potential from monthly precipitation and temperature values. The second model estimates the percent grain reduction due to delayed crop emergence. The grain yield model was adapted to commercial fields using a Productivity Index factor (PI). The PI is a measure of the productivity of other locations in relation to the Sherman Branch Experiment Station, using water-use-efficiency (WUE) as the basis of comparison. The field simulation of five fallow-crop precipitation patterns demonstrated that the maximum grain yield response occurred at 40 kg N (soil + fertilizer)/metric ton. The grain yield model demonstrated a 15% level of accuracy on a commercial field basis in both field trials and a survey of past production levels (1972-1980). It was hypothesized that the distribution of precipitation in the fallow and crop periods had an effect on both the amount and distribution of stored soil moisture. The field simulation demonstrated that more soil moisture was stored at the 90-240 cm depths by the patterns with more fallow season precipitation when measured in March of the crop year. Soil moisture storage and storage efficiencies fluctuated throughout the fallow and crop periods. At the cessation of the winter precipitation season in both the fallow and crop periods (March), the storage efficiency was highest when low levels of precipitation occurred. At this point in time, the mean crop period storage efficiency was 10% below the mean fallow period storage efficiency (34 and 44%, respectively) in both simulation studies. Soil moisture, temperature and immobilization requirements of crop residues interact to affect the net amount of nitrogen mineralization. The mineralization model proposed by Stanford and Smith (1972) was tested under field conditions. When the nitrogen immobilization requirement of the crop residues was included, the actual and predicted values were in agreement at the close of the 1978 fallow period. A nitrogen deficit was predicted at the 0-30 cm depth at the close of the 1980 fallow; however, the actual levels indicated a net accumulation of nitrate-nitrogen. Crop season mineralization, inferred from Mitscherlick and a-value extrapolations, in 1979 demonstrated that there was a decreasing amount of net mineralization during the crop season with increasing amounts of both fallow and crop season precipitation. Crop season mineralization in 1980 indicated that there was no net accumulation of nitrogen, rather a tie-up of 14 kg N/ha. This result reflects both the unsatisfied immobilization requirement predicted for the 1979 fallow season and crop season denitrification.
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The study of the vegetation of one of the natural coastal prairies in Oregon was undertaken for the purpose of describing some of its synecological features. Specific objectives of the study were to describe ...
Citation Citation
- Title:
- Synecological features of a natural headland prairie on the Oregon coast
- Author:
- Davidson, Eric Duncan
The study of the vegetation of one of the natural coastal prairies in Oregon was undertaken for the purpose of describing some of its synecological features. Specific objectives of the study were to describe certain plant assemblages in the study area, present phenological relationships on some of the assemblages, and discuss and illustrate some examples of evidence of succession on the study area. The study area is a prairie located on a headland about one mile north of the Tillamook-Lincoln county line (Sec. 3 in T6S, R11W). This prairie is one of the many situated on the headland bluffs and slopes along the northern Pacific coast. During an initial period of reconnaissance, familiarization with the plant species and communities in the study area was gained. Several surveys along most of the Oregon coast were made to compare the study area with other coastal prairies. A total of 38 distinctive stands of vegetation within the prairie were sampled in a series of five repetitive sessions from January to October in 1966. Presence and vegetative cover of species were recorded. In addition, soil depths in these stands were recorded. Seven transects from the prairie through the ecotone to the forest were established and the presence of species along them was recorded. With the aid of an association table five distinctive communities were differentiated in the sampled stands. These were: 1. Equisetum maximum community, restricted to sites with high soil moisture during the entire year. 2. Polystichum munitum-Rubus parviflorus community, usually on soils 18 inches deep or less. Species in this community form the major part of the ecotone vegetation. 3. Carex obnupta community, usually on soils 12 inches deep or less. Carex is the only important species in this community. 4. Artemisia suksdorfii-Solidago canadensis community, found on the exposed, south-facing end of the prairie on deep soils. It is a community found commonly in prairies farther north on the coast. 5. Solidago canadensis community, situated farther up in the prairie than the Artemisia-Solidago community, on deep soils. It was judged to be an earlier successional stage of the Artemisia-Solidago community. Two more groups were apparent in the table, but these were judged not to be distinct communities in the field. These were: 6. Lupinus littoralis group, considered part of the internal pattern of one or more of the large grassy communities not sampled. The peculiar grouping of Lupinus littoralis is attributed to the large, heavy seeds of that species which always drop directly to the ground, rather than being distributed farther by the wind. 7. Angelica lucida-Rubus spectabilis group, judged to be an aberrant form of the Polystichum-Rubus parviflorus community. A discussion of successional aspects of this and other coastal prairies on the Pacific coast was based on the results of field work carried out during this study, a knowledge of activities on this prairie from 1916 to the present time, and on historical accounts and old photographs concerning the coastal vegetation. It was tentatively concluded that the coastal prairies were maintained for long periods in the past mostly by fires set by the coastal Indians who lived on them. When the white settlers arrived with their cattle and sheep, many prairies, including the study area, were maintained by grazing pressure, and the spread of hardy introduced grasses was encouraged. The stands sampled in the study area were thought to have become established during a period of no stock grazing from 1938 to the present time. It was suggested that the Polystichum munitum-Rubus parviflorus community may provide sites for the growth of Picea sitchensis within this prairie.
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The characterization of bathymetry and its time evolution is very important for both oceanographic science applications, and for societal reasons relating to coastal engineering and development. Historically, ...
Citation Citation
- Title:
- Hybrid approach to estimating nearshore bathymetry using remote sensing
- Author:
- Catalán Mondaca, Patricio A.
The characterization of bathymetry and its time evolution is very important for both oceanographic science applications, and for societal reasons relating to coastal engineering and development. Historically, the process of depth surveying has been costly and labor-intensive. This is especially true in nearshore regions, hence a method that is both economic and reliable is of great interest. In this regard, depth inversion techniques take advantage of the interaction between the surface wave field and the underlying bathymetry such that observations of surface wave propagation can be coupled with a dispersion relation to infer bathymetry. Using field measurements, several different types of wave observation data have been tested in inversion methods, e.g. arrays of pressure sensors (Holland, 2001), marine radar (Bell, 1999), aerial photogrammetry (Dugan et al., 2001) and video imagery (Stockdon and Holman, 2000). Typically, these studies use the linear wave dispersion relation and measured wave phase speeds (c) to perform the inversion, and agreement is generally good in intermediate water depths in the absence of currents; errors increase as waves enter shallow water, increase in nonlinearity, and eventually break. In addition, numerical techniques exist that account for some nonlinear processes (e.g. Kennedy et al., 2000b; Misra et al., 2003) but they require more input data, usually in the form of high resolution free surface measurements. These nonlinear methods can potentially make improved depth estimates, however, they have only been tested with synthetic data. In this study, we undertake a novel approach for investigating phase speeds of nonlinear waves and the potential for using them for depth inversions. The approach is novel in the sense that our observational data set consists of both in situ and remotely sensed data and also high resolution numerical data for interpolating between the in situ measurements. Our observations were made from a set of laboratory experiments conducted in large scale wave flume. Laboratory wave conditions included both regular and random waves and a range of wave heights and periods were considered. The final data set used for the depth inversion algorithm was reduced to regular cases only. The wave height profile H(x) is simulated with high spatial resolution using a combined refraction/difraction model REF/DIF1 (Kirby and Dairymple, 1994), where the in situ data is used for calibration. Next, wave parameters such as phase speed, wavenumber and frequency are estimated based on the remote video measurements. The resulting hybrid data set is used as input for performing depth inversion including nonlinearity using the composite dispersion relation of Kirby and Dalrymple (1986). Results indicate that inclusion of nonlinearity significantly improves the retrieved depths, especially in shallow water. The resulting degree of accuracy is comparable with previous observations for intermediate water. Analysis of the error suggests that the main source of error can be attributed to the phase speed estimation, thus it is apparent that the composite dispersion equation is capable of explaining the principal physical process well.
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375. [Article] Tidal and atmospheric forcing of the upper ocean in the Gulf of California, Part 2: Surface heat flux
Satellite infrared imagery and coastal meteorological data for March 1984 through February 1985 are used to estimate the net annual surface heat flux for the northern Gulf of California. The average annual ...Citation Citation
- Title:
- Tidal and atmospheric forcing of the upper ocean in the Gulf of California, Part 2: Surface heat flux
- Author:
- Abbott, Mark R., Winant, Clinton D., Paden, Cynthia A.
Satellite infrared imagery and coastal meteorological data for March 1984 through February 1985 are used to estimate the net annual surface heat flux for the northern Gulf of California. The average annual surface heat flux for the area north of Guaymas and Santa Rosalia is estimated to be +74 W m-2 for the 1984–1985 time period. This is comparable to the +20–50 W m-2 previously obtained from heat and freshwater transport estimates made with hydrographic surveys from different years and months. The spatial distribution of the net surface heat flux shows a net gain of heat over the whole northern gulf. Except for a local maximum near San Esteban Island, the largest heat gain (+110–120 W m-2) occurs in the Ballenas and Salsipuedes channels, where strong tidal mixing produces anomalously cold sea surface temperatures (SSTs) over much of the year. The lowest heat gain occurs in the Guaymas Basin (+40–50 W m-2), where SSTs are consistently warmer. In the relatively shallow northern basin the net surface heat flux is fairly uniform, with a net annual gain of approximately +70 W m-2. A local minimum in heat gain (approximately +60 W m-2) is observed over the shelf in the northwest, where spring and summer surface temperatures are particularly high. A similar minimum in heat gain over the shelf was observed in a separate study in which historical SSTs and 7 years (1979–1986) of meteorological data from Puerto Penasco were used to estimate the net surface heat flux for the northern basin. In that study, however, the heat fluxes were higher, with a gain of +100 W m-2 over the shelf and +114 W m-2 in the northern basin. These larger values are directly attributable to the higher humidities in the 1979–1986 study compared to the 1984-1985 satellite study. Significant interannual variations in humidity appear to occur in the northern gulf, with relatively high humidities during El Niño years and low humidities during anti-El Niño years. High humidities reduce evaporation and the associated latent heat loss, promoting a net annual heat gain. In the northern Gulf of California, however, tidal mixing appears to play a key role in the observed gain of heat. Deep mixing in the island region produces a persistent pool of cold water which is mixed horizontally by the large-scale circulation, lowering surface temperatures over most of the northern gulf. These cold SSTs decrease evaporation by reducing the saturation vapor pressure of the overlying air. As a result, heat loss is substantially reduced, even when humidities are low. By removing heat from the surface, tidal mixing alters the time scale of air-sea interaction and reduces or possibly even inhibits the formation of deep water masses via convection. Over climatological timescales, it may be tidal mixing that ultimately maintains the estuarinelike circulation in the northern Gulf of California, differentiating it from the Mediterranean and Red seas, which lose heat to the atmosphere.
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377. [Article] Dynamics of Vector-Host Interactions in Avian Communities in Four Eastern Equine Encephalitis Virus Foci in the Northeastern US
This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by the Public Library of Science. The published article can be found at: http://journals.plos.org/...Citation Citation
- Title:
- Dynamics of Vector-Host Interactions in Avian Communities in Four Eastern Equine Encephalitis Virus Foci in the Northeastern US
- Author:
- Molaei, Goudarz, Andreadis, Theodore G., Armstrong, Philip M., Muller, Tim, Thomas, Michael C., Shepard, John J., Medlock, Jan
This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by the Public Library of Science. The published article can be found at: http://journals.plos.org/plosntds/
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378. [Article] Canyon Grasslands of the Hells Canyon National Recreation Area : How have they changed over time and what is their future trajectory?
The canyon grasslands of the Hells Canyon National Recreation Area (HCNRA) are a unique ecosystem within the Pacific Northwest Bunchgrass Region (PNWBR) with a long history of natural and anthropogenic ...Citation Citation
- Title:
- Canyon Grasslands of the Hells Canyon National Recreation Area : How have they changed over time and what is their future trajectory?
- Author:
- Pack, Samantha J.
The canyon grasslands of the Hells Canyon National Recreation Area (HCNRA) are a unique ecosystem within the Pacific Northwest Bunchgrass Region (PNWBR) with a long history of natural and anthropogenic disturbances including fire, invasive species introduction, historical livestock grazing, and cultivation. Even with this history, these canyon grasslands contain some of the last remnants of the Pacific Northwest Bunchgrass Region. For thousands of years, these grasslands were occupied by the Nez Perce Tribe and have been grazed since the 1700s. In addition to grazing, settlers cultivated many parts of the HCNRA and some of these homesteads can still be seen today. Both historical and current land uses are strongly influenced by the natural topography of these canyon grasslands, with the highest concentration of land use centered on benchlands while steep canyon slopes avoided cultivation and were used less by livestock. The different plant associations of these grasslands are also influenced by the unique topography of the HCNRA due to the relationships between soil moisture and depth and abrupt alterations in aspect, slope, and elevation. Very few studies have examined the plant associations of the canyon grasslands of the HCNRA, even fewer have asked how they have changed over time, and there are no studies looking into their future trajectory by assessing the seed bank. The first study in my thesis (Chapter 2) focused on how canyon grasslands have changed over time using a repeated survey of vegetation from four different plant associations within the Lower Imnaha Subbasin. From the original study conducted in 1981, a total of 19 different plots in four plant associations were chosen to be resampled in 2014. Since the original study was used to classify seral stages within the plant associations, these successional stages were used to determine if the plant communities had transitioned between the seral classes over the 33 year-time-period. In addition, given the importance of topography to these grasslands, elevation, slope, and aspect were evaluated for their relationship to successional changes. Both Nonmetric Multidimensional Scaling (NMS) and Indicator Species Analysis were used to verify the seral stage classifications for each plot in 1981 and 2014. To evaluate how each association had changed between sampling years, Multi-response Permutation Procedures (MRPP) and NMS were used. Most of these plant associations were relatively stable and had, for the most part, remained at the same seral stage or transitioned to a later seral stage. Among the plant associations, slope was the topographical variable that appeared most related to the transitions in seral stages. Steeper slopes either remained at the same seral stage or transitioned to a later one, while gentler slopes (< 20%) tended to shift from later to earlier seral stages. A relatively new introduced annual grass to the region, Ventenata dubia (not present in the 1981 sampling), was found in three of the four plant associations and was most abundant on the benchlands. The results of this resurvey suggest that topography is related to both the distribution of plant associations and which sites will shift in seral stage over time across the canyon grasslands of the Lower Imnaha Subbasin. The second study of my thesis (Chapter 3) focused on using a seed bank study as one of the many ways to examine the future trajectory of the plant communities in the canyon grasslands of the Lower Imnaha Subbasin, with a particular focus on the benchlands. The seed bank contains the regenerative pool for plant communities and represents the potential for a community to respond to disturbances. The seed bank from benchland sites in one plant association was evaluated in relation to the standing vegetation, successional stage, and historical cultivation. To my knowledge, this was the first seed bank study for the grasslands of this region. Vegetation cover and soil samples were collected from 8 sites, including two previously cultivated and two reference noncultivated sites. NMS was used to extract the strongest community gradients, which naturally separated out the seral stage classifications of the vegetation. To evaluate differences between the vegetation and the seed bank, between successional stages, and between cultivation histories, MRPP was used. Results from the seed bank study are consistent with many other studies around the world in perennial grasslands showing that the vegetation and seed bank are often dissimilar. Similarities between the vegetation and seed bank were highest in the annual grass dominated stage compared to the early seral stage. The effects of cultivation appear to still be evident in the seed bank, where cultivated sites have significantly more introduced grasses compared to noncultivated sites (p < 0.05). There was an overall greater abundance of introduced annual forb and grass species in the seed bank on these benchland sites, suggesting that they may be native seed limited and could easily shift to invasive species dominance after further disturbance, especially on previously cultivated areas. The results of both of these studies suggest that benchlands and lower sloped sites surrounding them in the canyon grasslands of the Lower Imnaha Subbasin may less resistant and resilient to disturbance. Priorities for future research and management may also need to focus on the plant communities of benchlands in these unique grasslands.
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379. [Article] The historic and contemporary ecology of western Cascade meadows : archeology, vegetation, and macromoth ecology
Montane meadows in the western Cascades of Oregon occupy approximately 5% of the landscape, but contribute greatly to the region's biodiversity. Western Cascades meadows are dynamic parts of the landscape ...Citation Citation
- Title:
- The historic and contemporary ecology of western Cascade meadows : archeology, vegetation, and macromoth ecology
- Author:
- Highland, Steven A.
Montane meadows in the western Cascades of Oregon occupy approximately 5% of the landscape, but contribute greatly to the region's biodiversity. Western Cascades meadows are dynamic parts of the landscape and have contracted by over 50% in the past two hundred years in the HJ Andrews Experimental Forest (hereafter Andrews Forest). Many studies have linked the loss of meadows with local extirpation of species and loss of regional biodiversity, but these processes depend upon the factors that create and maintain meadows, and how species respond to meadow configuration. The prehistory of these meadows is poorly understood, as is the contemporary ecology. This study combined previously collected archeological and moth datasets, aerial photographs, and new plant, tree core, and moth data to investigate interactions between landforms, disturbance, vegetation, and moth abundance and diversity in montane meadows of the western Cascades of Oregon. Burning by prehistoric people may have created and maintained montane meadows, but relatively little evidence remains of the activities of prehistoric peoples in the western Cascades. This study assessed the extent to which prehistoric people preferentially used different landforms and vegetation types by inferring use from landscape distributions of archaeological sites. Descriptions of 359 previously recorded and four newly discovered archeological sites in the McKenzie River watershed of western Oregon were examined using GIS and chi-square analysis to determine how sites were distributed relative to classified vegetation and landforms of the 3700-km² McKenzie River watershed. The high ridges of the HJ Andrews Experimental Forest were analyzed using air photo change detection and archaeological field surveys to identify how archeological sites were distributed relative to landforms and vegetation communities, including meadows. The field surveys documented physical evidence (archeological sites) confirming Native American use of the meadows and surrounding open forests. The locations of these sites indicate that Native Americans utilized the edges between large open meadows and open forests, as well as gently sloping open meadows. The prior extent of meadows (before air photos) was estimated by dendrochronology of 220 trees along present-day and inferred past meadow edges. Forest age structure and the open-grown forms of Douglas fir suggests a much more open habitat, potentially due to fire, was present more than 200 years ago. Moths are major consumers of vegetation when in caterpillar stage and are food sources for many birds and mammals, and contribute greatly to the insect diversity in a region. Moth species richness and abundance may be associated with the distribution of vegetation communities and seasonal timing, and the conservation of rare moths may depend on the conservation of rare vegetation habitats. A dataset of moths sampled 10 times/year at 20 locations in the 64-km² Andrews Forest over the period 2004-2008 was analyzed using generalized linear mixed models (GLMM), non-metric multidimensional scaling (NMS), multi-response permutation procedure (MRPP), analysis of variance (ANOVA), and two tailed t-test to identify the overall patterns of rare and common moth distribution as well as moth community relationships to structurally and taxonomically derived vegetation classes and seasonality. Five hundred fourteen species and 69,168 macromoth individuals were identified. Moth species abundance and diversity were significantly higher in low elevation coniferous forests than in other vegetation types, according to the GLMM. Sixty-six rare moth species were significantly associated with high elevation open habitats. Species associated with meadows also were significantly more likely to be hardwood or herb-feeders than conifer-feeders as caterpillars, based on ANOVAs. The 26 most common moth species were significantly associated with low elevation coniferous forests and were more likely to be conifer-feeders as caterpillars, based on ANOVAs. Common moth species were significantly more likely to emerge earlier in warmer years than in cooler years, based on a two-tailed t-test. Managing the western Cascades landscape for moth biodiversity and for moth abundance requires maintenance and potentially expansion of rare upland habitats as well as lowland coniferous forests. Montane meadows in the Andrews Forest are contracting in size, but it is not known how these changes have affected moth and plant biodiversity. The rate and pattern of meadow contraction from 1949 to 2005 along the high ridges of the Andrews Forest were analyzed using air photo change detection. Overall meadows contracted by nearly 50% from 1949 to 2005, but rates of meadow loss were much higher for the largest meadow complexes. Plant community diversity in seventeen meadows and the diversity, abundance, and community structure of moths at 98 locations sampled in the summers of 2008, 2009, and 2010 were related to measures of meadow size, isolation, and other variables using cluster analysis (CLA), MRPP, NMS, and generalized additive models (GAMs). Plant diversity in meadows was significantly positively related to meadow area in 1949 and the distance of the meadow from the road, based on GAM analysis. Plant community structure was most closely correlated with meadow area in 1949 and slope, based on CLA, MRPP, and NMS analysis. Calendar day explained the most variation in moth species richness, abundance, and community structure, but the next most important explanatory variables differed according to feeding guild, based on GAMs. Richness, abundance, and community structure of herb-feeding moths was related to meadow area in 1949 and elevation. For angiosperm-feeding moths, area-perimeter ratio in 2005 explained the most variation in richness, abundance, and community structure after calendar day. For gymnosperm-feeding moths, meadow area change from 1949-2005, a variable measuring the amount of increase in coniferous tree cover, explained the most variation in richness, abundance, and community structure after calendar day. The abundance and diversity of herb-feeding moths and meadow plants exhibited a lagged response to habitat loss, which may indicate an extinction debt. In contrast, angiosperm-and gymnosperm-feeding moths responded quickly (within 50 years) to increases in their habitat. Managing for the conservation of biodiversity in the upper elevations of the Andrews Forest will require targeted management strategies for different groups of organisms. Herb-feeding moths and meadow plants will benefit from expansion of open meadow habitat, while angiosperm and gymnosperm-feeders will require the maintenance of edge environments and coniferous forests.
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380. [Article] Predictability and Constraints on the Structure of Ecological Communities in the Context of Climate Change
Ecologists must increasingly balance the need for accurate predictions about how ecosystems will be affected by climate change, against the fact that making such predictions at the ecosystem-level may ...Citation Citation
- Title:
- Predictability and Constraints on the Structure of Ecological Communities in the Context of Climate Change
- Author:
- Barner, Allison K.
Ecologists must increasingly balance the need for accurate predictions about how ecosystems will be affected by climate change, against the fact that making such predictions at the ecosystem-level may be infeasible. Although information about responses of individual species to a changing environment is increasing, scaling such information to the community level is challenging. To date, predicting responses of ecological communities to climate change is constrained by limited theoretical and empirical knowledge about the response of communities and ecosystems to change. My dissertation addresses several knowledge gaps in our understanding of community structure under climate change. This research draws from a rich experimental tradition in the species-diverse model ecosystem of the US Pacific Northwest rocky intertidal to test ecological theory. In Chapter 2, I assessed whether the response of multiple species of coralline algae to global change could be predicted from basic first principles of chemistry, physiology, and ecology. Given the rate of global change, and the time-consuming process of experimentally determining species responses to climate change, I hypothesized that species can be grouped using existing theory, either by their evolutionary relatedness or by their ecological traits, such that climate responses are similar within a group. Such a scheme would greatly reduce the number of experiments needed to characterize species climate vulnerability, requiring the characterization of the response of groups of species to climate change, rather than individual species. Using a suite of five co-occurring species of intertidal articulated coralline algae (Corallina vancouveriensis, Corallina officinalis, Bossiella plumosa, Bossiella orbiginiana, and Calliarthron tuberculosum), I applied this framework to generate ten mutually exclusive hypotheses that could explain organismal response to ocean acidification, a consequence of global climate change that threatens marine calcifying species. I found that all species had similar responses to ocean acidification, and that responses were generally predicted by the body size of the individual. Despite the power that such a framework provides in understanding group-level response to climate change, predicting community-level response requires knowledge of how organisms affect one another. In Chapter 3, I quantified species interactions in a series of removal experiments to estimate the reciprocal effects between a canopy-forming intertidal kelp (Saccharina sessilis) and a suite of understory species that persist beneath the kelp canopy. This experiment was replicated in different oceanographic conditions across a large latitudinal gradient, as a step towards understanding how interactions might change with climate change. However, the experiment demonstrated that interactions between the canopy and understory were consistent among different environmental conditions. Furthermore, the strongest effect was that of understory species, particularly articulated coralline turf algae, on the canopy species. The coralline turf algae both facilitated the recruitment of the canopy species and buffered the canopy from abiotic stress during its adult life stage. Combining experimental results and observational surveys, a hypothesized interaction network for these species was constructed, highlighting the importance of direct and indirect species interactions in promoting species coexistence. A long-standing controversy in ecology is whether or not species interactions can be inferred from observational data, as opposed to from experimental tests. Although the rocky intertidal ecosystem is unique for its ease of experimental manipulation, quantifying species interactions experimentally is often difficult or impossible. As an alternative, many have turned to statistical methods to estimate species interactions from observational data, namely, from patterns in species pairwise co-occurrences. In Chapter 4, I examined these co-occurrence methods and their potential relationship to experimentally measured species interactions. I first used a suite of different co-occurrence methods to generate a set of predicted species interactions of macrophytes and invertebrates from observational surveys conducted in the rocky intertidal zone of Oregon. I then compared the predicted species interactions to the same pairwise species interactions determined experimentally and assembled from the literature. Overall, of the seven methods tested, each generated a different set of predicted species interactions from the same data, and all methods predicted interactions that did not match those in the experimental database. Thus, predicting species interactions from patterns in occurrence remains elusive. Importantly, much work remains to be done to understand the link between species co-occurrences and their actual interactions with one another on the landscape. A key limiting frontier in climate change ecology is determining the influence of species interactions on species distributions across the landscape, and the sensitivity of such interactions to changes in climate. Finally, in Chapter 5, I used theory from the published literature and knowledge from my previous chapters to make predictions the recovery of low rocky intertidal communities after a disturbance. The process of community development after disturbance has been studied in many ways, from the successional studies of the early 1900s, to modern community assembly theory. In recent years, a focus on the unpredictability of community assembly has emerged, paying particular attention to the role of historical contingency, or priority effects, in determining the recovery trajectory of a community. Priority effects occur when the arrival of a species after a disturbance inalterably changes the composition of the developing community, driving the assembly of widely different communities at a small spatial scale. I conducted a community assembly experiment in three different low intertidal zone community "types", each characterized by different dominant macrophyte species (Saccharina sessilis, Phyllospadix spp., and algal "turfs"). Replicating this experiment at six sites along the Oregon coast, I found that both regional and local dynamics constrain the recovery of communities after disturbance. Half of the time, the community returned to the state of the nearby community type. The remaining communities were influenced by priority effects that could be predicted based on 1) regional dynamics favoring some species over others, or 2) the timing of arrival of important facilitating species. Overall, understanding the dynamic relationship between the persistence of diverse communities and a changing environment remains one of the challenges of our time. My dissertation highlights some of the challenges in predicting the future composition of communities under climate change, but also provides some ways forward. Integration of experimental, theoretical, and observational studies builds the scaffolding of prediction, whereby understanding the constraints on species physiology, the interactions among species, and community assembly can help frame the context in which predictions are made.