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561. [Article] Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest
Forest harvest persists as one of the most globally important industries, and crucially provides raw wood products for both building and fuel materials. Mechanistically complex abiotic and biotic processes ...Citation Citation
- Title:
- Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest
- Author:
- Danielson, Rachel E.
Forest harvest persists as one of the most globally important industries, and crucially provides raw wood products for both building and fuel materials. Mechanistically complex abiotic and biotic processes curb ecosystem recovery following timber harvest and it is of great importance to understand the effects of this practice on biogeochemical cycling and ecosystem function to determine the potential for long-term sustainability. This thesis was motivated by a lack of comprehensive understanding as to the consistency of preexisting and post-harvest microbially mediated process rates and community composition across a large region of the same dominant vegetation type. I sought to determine how timber harvest across the Pacific Northwest impacts microbial biogeochemical cycling activity and community structure of both prokaryotic and fungal communities in response to harvest. At nine managed Douglas-fir forests, samples were collected from exact locations within sites one year prior to and twelve to fifteen months following clear-cut harvesting. The objective of the first study was to determine the degree of variability in microbially mediated process rates and pools of C and N, and generalized trends that are evident across sites one year following harvest. Samples were analyzed for various C and N pools, and the potential activities of biogeochemically important extracellular enzymes were measured. Soil incubations were performed to determine respiration rate and N production over time. Soil DNA isolates were used to quantify 16S rRNA and ITS gene copy numbers using qPCR, and all measurements were statistically compared between pre-and post-harvest samples. Total soil C and N did not change significantly following harvest, but the C: N ratio of dissolved components decreased consistently and biomass C: N ratios generally increased. Activities of β-glucosidase and cellobiohydrolase increased significantly whereas activities of phenol oxidase and peroxidase decreased significantly. Cumulative respiration over the incubation period declined substantially, and total N pools changed from primarily DON pre-harvest, to primarily NO₃⁻post-harvest. Changes in activity rates and pool sizes following harvest were generally related to C to N balances. Pre-harvest measurements suggested communities may be co-limited by C and N, while the emergence of strong C limitation was evident post-harvest. The generalized trends identified from this study can be used in future research as reference points for ecosystem status during forest succession, and for correlation with an investigation of changes in microbial community composition and structure. The objective of the second study was to determine the factors shaping soil microbial communities of Douglas-fir forests in the Pacific Northwest, and to identify generalized short-term effects of timber harvest on the richness, diversity, and structureof these communities. DNA was extracted from soils and sequenced using the Illumina® Miseq platform to determine differences in prokaryotic and fungal communities. When communities were considered separately pre-and post-harvest, pH most consistently explained community dissimilarity among sites. Although community dispersion did not vary between pre-and post-harvest samples, OTU richness was consistently and significantly higher following tree removal. Both prokaryotic and fungal community structures were significantly different in post-compared to pre-harvest soils, even when just OTUs representing the top 50% of sequences were considered. Relative abundance of the dominant three bacterial phyla (Proteobacteria, Acidobacteria, and Verrucomicrobia) did not change significantly following harvest, but some less-represented phyla decreased (Actinobacteria) or increased (Bacteroidetes) significantly in relative abundance. Basidiomycota abundance decreased significantly whereas Ascomycota and Zygomycota abundance increased. Ectomycorrhizal fungi were enriched across pre-harvest samples, whereas many known saprotrophic species were enriched post-harvest. In conclusion, general alterations in fungal communities, as well as select bacterial and archaeal taxa, may serve as appropriate indicators of disturbance and ecosystem status across this region.
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562. [Article] Fire history of the ponderosa pine forests of the Warm Springs Indian Reservation, Oregon
Fire has played a prominent role in the development and character of the ponderosa pine forests in western North American. Its records are written in the scars of trees that have survived the fire. Careful ...Citation Citation
- Title:
- Fire history of the ponderosa pine forests of the Warm Springs Indian Reservation, Oregon
- Author:
- Soeriaatmadja, Roehajat Emon, 1936-
Fire has played a prominent role in the development and character of the ponderosa pine forests in western North American. Its records are written in the scars of trees that have survived the fire. Careful studies of these fire-scars may be used as a means of reconstructing the fire history of the forest. This study was conducted in the Warm Springs Indian Reservation of the east side of the Cascades in Oregon, and was aimed at describing the fire history of the area in terms of frequency of occurrence, extent, and chronology, as these relate to somewhat different climate, topography, and vegetation structure found within the ponderosa pine zone in this area. Since accurate interpretation of the fire history generally required the exposure of the fire-scarred stumps through felling, the study areas were selected where tree felling was recent or in progress. Four study areas were selected within the Warm Springs Indian Reservation. These areas were located within the cutting boundaries of the Tenino Bench, Seekseequa, Boulder Creek and Lionshead logging units. A total of 305 fire-scarred stumps were sampled during the course of the study. Information concerning the character of the stand in the vicinity of the fire-scarred stumps was obtained from 100 x 100 foot plots. The fire-scarred stumps provided data pertinent to the frequency of fires during the past as indicated by the presence of successive ring scars. The date of a given fire was determined by counting the number of annual growth rings formed since the occurrence of the ring scar. For the Tenino Bench area, numbers of successive ring scars observed on the stumps ranged from 5 to 23 with an average 9.4 per stump. Forty-seven percent of the total number of fire-scarred stumps sampled showed seven, eight, nine and ten successive ring scars with an average time interval of 16.5 years between the ring scars. Average minimum and maximum time intervals between the ring scars on the fire-scarred stumps observed on the Tenino Bench study area were 6.5 and 36.3 years respectively. The number of successive ring scars on individual fire-scarred stumps averaged 10.8 in the Seekseequa area. Seventy-eight percent of the trees observed here showed 7 to 12 successive ring scars. The least number of ring scars occurring on any given stump was six. The greatest number was 25. The average time interval between ring scars was 14.2 years with an average minimum interval of 6.2 years and the average maximum interval of 28.8 years. A sharp reduction in the number of successive ring scars per individual tree is noted in the Boulder Creek and Lionshead study areas located at higher elevations. Thirty-two percent of the total number of stumps examined in the Boulder Creek area showed two, three and four successive ring scars with an average of 7.2 per stump. The bulk of the trees sampled showed numbers of ring scars ranging from two to ten. On the Lionshead area 63 percent of the trees showed less than seven successive ring scars. The average number of successive ring scars per stump was 6.3. The maximum number of successive ring scars observed in this area was 14. Although the frequency of fires was higher in the two most xeric areas (Tenino Bench and Seekseequa) these fires did not appear to be as severe (as evidenced by the size of the fire-scars) as the two more mesic areas (Boulder Creek and Lionshead). The difference in frequency and severity of fires within the ponderosa pine zone appears in part related to the susceptability of the area to fire and the accumulation of the fuel materials. The greater frequency of less severe fire in the lower part of the pine zone may be due to the more open nature of the stand and the slower accumulation of fuel materials. The more moist conditions of the forest at higher elevation may explain the less frequent occurrence of fire. However, because of the more dense nature of the forest and especially the presence of young age classes of more shade tolerant tree species, once fires do become started the possibility of the fire escalating to the crown type fire is greater. Ring scar evidence during the past 400 years indicates a sharp reduction in the frequency of fire since 1900. This marked decline in the occurrence of fire reflects the effectiveness of fire control efforts instigated by Federal Agencies in recent years. Changes in the composition and structure of this forest as a result of fire exclusion are noted.
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563. [Article] Vegetation and animal responses to grazing crested wheatgrass at three intensities and two seasons in southern Idaho
Land useable for livestock grazing in the western United States is diminishing because of spreading municipalities, irrigation developments, highway construction, recreational demands and withdrawals. Concurrently, ...Citation Citation
- Title:
- Vegetation and animal responses to grazing crested wheatgrass at three intensities and two seasons in southern Idaho
- Author:
- Sharp, Lee Ajax
Land useable for livestock grazing in the western United States is diminishing because of spreading municipalities, irrigation developments, highway construction, recreational demands and withdrawals. Concurrently, the demand for livestock and livestock products is increasing because of a rapidly growing population. As a result, production from the grazing land that remains must be increased to satisfy the increased wants of the population. Artificial seeding is improving the forage productivity on large areas of low producing range land in the Intermountain region. Methods of successfully establishing stands of forage plants by artificial means are reasonably well understood, but less information is available about grazing practices that will optimize the returns from these range improvement programs. A nine-year (1957-1965) grazing study was conducted on a crested wheatgrass (Agropyron cristatum and A. desertorum) seeding near Malta, Idaho for the purpose of evaluating plant and animal responses under three intensities of grazing (light, moderate or heavy) in two seasons (spring or fall). With the information obtained, suggested grazing practices for optimum livestock production were developed. Stand density, frequency of occurrence and yield of crested wheatgrass were not affected appreciably during the nine years by light and moderate grazing intensities in the spring. Heavy spring grazing, however, caused a reduction in frequency of occurrence and a lower yield of crested wheatgrass in the latter years of the study. Intensity of grazing in the fall season had little effect on stand density, frequency of occurrence or annual yield of crested wheatgrass. Initial herbage production in the spring was found to be related to the amount of residue remaining after grazing in the previous year. In the heavy spring grazing treatment, each 100 pounds of increased residue produced an average increase of 64 pounds of initial growth. Gains per animal, average daily gains and gains per acre were higher in the spring treatments than in the fall treatments. Average gain per animal and average daily gains were greatest under light and least under heavy grazing in both seasons. Average gains per acre, however, were higher under heavy grazing than light or moderate grazing in both seasons. Plant and animal responses indicate that moderate grazing from early May to late June maintained forage productivity and produced optimum animal response. Forage was wasted with light spring grazing and heavy spring grazing caused a decline in plant vigor, forage productivity and animal response. It was revealed in this study, however, that vigor and production of heavily grazed crested wheatgrass stands could be improved by deferment of grazing for a growing season or two. All intensities of grazing in the fall maintained vigor and production of crested wheatgrass. Gains per animal were slightly less under heavy fall grazing but gains per acre were slightly more than under light or moderate grazing in this season. Information obtained on plant and animal responses indicated that greater livestock production may be realized if the area to be grazed is divided into two or more sections. When this is done, grazing can be alternated between or among the sections in such a way as to allow maximum opportunity for stand maintenance, forage production and animal response. The effectiveness of management programs that developed can be judged by observing the vigor and frequency of occurrence of crested wheatgrass. Dead centers and fragmentation of individual plants of crested wheatgrass occur when grazing is excessive and annual plant species increase in density and frequency. The fragmentation of crested wheatgrass plants into smaller unite made density estimates a less sensitive indication of plant response to grazing than frequency of occurrence. Grazing is abnormally patchy and coarse unpalatable plants are common when the forage is grazed at less than capacity.
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564. [Article] Four centuries of soil carbon and nitrogen change after severe fire in a Western Cascades forest landscape
Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare. Consequently, long-term effects of fire on soils are often ...Citation Citation
- Title:
- Four centuries of soil carbon and nitrogen change after severe fire in a Western Cascades forest landscape
- Author:
- Giesen, Thomas William
Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare. Consequently, long-term effects of fire on soils are often hypothesized from short-term effects. In a chronosequence study, I studied 24 western Cascades (Oregon) forest stands thought to have been initiated in fire. Twelve of those burned about 150 years ago (“young” sites), and the other 12 burned an average of 550 years ago (“old” sites). I hypothesized that young stands would have less carbon (C) and nitrogen (N) in forest floor and in 0 -10 cm mineral soil than old stands. I found that forest floor N pools of old sites (average = 1,823 kg/ha ± s.e. = 132 kg/ha) were significantly greater than young sites (1,450 ± 98 kg/ha). Similarly, forest floor C pools of old sites (62,980 ± 5,403 kg/ha) were significantly greater than young sites (49,032 ± 2,965 kg/ha). Greater N and C pools in forest floor of old sites resulted from greater forest floor mass in old sites; concentrations of both N and C, and C:N ratios, did not differ significantly by forest age class. In mineral soil, neither concentrations nor pools of N and C differed between young and old sites. Despite overall similarity of C:N ratios in young versus old sites, potential N mineralization rates were twice as high in forest floor of old sites (average = 60 ± 7.3 mg N / g soil) than young sites (26 ± 3.5 mg N / g soil), . Nitrate accounted for only 2% or less of total N mineralized in forest floor samples. In mineral soil, potential net N mineralization did not differ by forest age class. The pattern of high net N mineralization and low nitrification in old forests is consistent with other studies of fire-prone forests, yet contrasts with many studies of forests that lack fire, and suggests that ammonium is not the sole control over nitrification in fire-prone ecosystems. Overall, fire appears to impart a longterm legacy of reduced forest floor N and C pools in this western Oregon Cascades landscape, which suggests that current fire-suppression activities in the region may increase forest floor N and C storage over historical conditions within several centuries. The differences in forest floor and soil N cycling processes that I observed by forest age class raise the further possibility that fire exclusion in these forests may change the relative abundance of soil inorganic N forms to favor ammonium over nitrate. Such changes may have unknown consequences for relative competitive abilities of plant and microbial species that rely preferentially on different N-forms to meet N nutrition requirements. While forest floor N and C pools increase from young to old stands, forest floor and soil N and C pools are not different, or decline, between 450 year old stands and the oldest stands at 800+ years, That, and other, anomalous changes in values from ~450 to 800+ years, suggest possible changes in ecosystem functions, and may indicate that this landscape could be a fruitful study area for examinations of a mature, steady-state ecosystem
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The collagen content and composition of collagens in different age classes of shrimp were determined. Their physical and chemical characteristics were investigated. The interrelationship of shrimp size ...
Citation Citation
- Title:
- Characterization of the collagen protein in smooth pink shrimp (Pandalus jordani)
- Author:
- Akel, Phillip John
The collagen content and composition of collagens in different age classes of shrimp were determined. Their physical and chemical characteristics were investigated. The interrelationship of shrimp size and muscle collagen content to raw and cooked meat yield was established. Total collagen content for three lots of round shrimp with weights averaging 2.58±.39, 5.27±.55 and 7.72±.96 g was determined to be 2.36, 3.35 and 3.47 mg collagen/g total musculature N, respectively. Unformed collagen comprised 53.85, 35.52 and 0.86% of the total collagen content, respectively. Maturation, as reflected by shrimp size, was accompanied by a near linear increase in formed collagen. A molecular weight of 310,000 for shrimp collagen was determined using SDS gel electrophoresis. The accuracy of this determination was compromised by limited mobility and lack of standard reference proteins of appropriate molecular weight, but did establish a molecular weight in a range common to other collagens. Variations in the amino acid composition of formed and unformed collagen reflected the function of the tissues in the musculature from which they were derived. Formed collagen contained higher amounts of glycine, proline and hydroxylysine than unformed collagen, providing a chemical basis for its structural function in formed connective tissues. Remaining amino acids, except histidine, glutamate and arginine were contained in higher amounts in unformed collagen. Unformed collagen also contained a substantial amount of unidentified components which were suspected to be amino sugar derivatives. Only trace amounts of these components were found in formed collagen. Shrimp collagen contained unusually low levels of glycine, only trace amounts of hydroxyproline and substantial quantities of tryptophan. Glycine and hydroxyproline are important amino acids in mammalian collagens, but tryptophan is usually not present. Shrimp collagen also contained higher levels of threonine, tyrosine, hydroxylysine, valine, methionine, leucine, isoleucine and phenylalanine than most other reported collagens. These variations in amino acid composition seem to reflect a requirement for a structural protein possessing unique characteristics commensurate with the anatomical structure of the species. The yield (% dry wt.) of raw and cooked (100 sec; 101°C in steam) derived through hand peeling round shrimp, was correlated (P>.001) in a positive manner by well defined power functions. Raw meat yield (% dry wt.) declined during ice storage in a linear (P>.001) manner at a rate dependent upon shrimp size. The more rapid loss of solids from large shrimp reduced yield differences as storage was extended. Raw meat losses during ice storage ranged from 0.298 to 0.318 g raw meat dry matter/100 g round shrimp/day for 2.5 and 7.5 g shrimp respectively. Dry matter weight loss from raw meat through the washing action of melting ice, was replaced in a linear (P>.05-P>.005) manner with water to maintain yield (% wet wt.) during storage. Ice storage expanded cooked yield (% dry wt.) differences between shrimp sizes. Meat losses through cooking mediated by ice storage, ranged from 0.421 to 0.303 g cooked meat dry matter/100 g round shrimp/day for 2.5 and 7.5 g shrimp, respectively. The age class dependent content and composition of collagens in the musculature of shrimp was reflected in the recovery of raw and cooked meat. Meat from small shrimp contained higher levels of unformed collagen which possessed less dry matter and degraded more rapidly in ice storage. Proteolytic action on elevated levels of unformed collagen was not reflected in the rate of ice storage losses. But, it markedly increased heat induced solubilization of solids and enhanced moisture retention through steam precooking over larger shrimp. Maturation of shrimp associated with more formed and less unformed collagen reduced solids solubilization and moisture retention through steam precooking.
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566. [Article] Comparing structure and development of Douglas-fir old-growth, plantations, and young natural forests in western Oregon
Ages, diameter growth, density, tree size, and species were studied in old-growth, plantation, and young natural Douglas-fir stands in three areas in western Oregon: the western and eastern Coast Range ...Citation Citation
- Title:
- Comparing structure and development of Douglas-fir old-growth, plantations, and young natural forests in western Oregon
- Author:
- Dowling, Christopher D.
Ages, diameter growth, density, tree size, and species were studied in old-growth, plantation, and young natural Douglas-fir stands in three areas in western Oregon: the western and eastern Coast Range and the western Cascades. The purpose was to compare the development of these three stand types and to determine whether plantations and young natural stands would develop old-growth structures and characteristics. The Douglas-fir age ranges in plantations (8 to 15 yr) were much narrower and than the ranges of tree ages found in the young natural (21 to 102 yr) and in the old-growth stands (300 to 354 yr). This wide range of tree ages, along with diameter growth rates and tree and stand structural characteristics, supported the hypothesis that old-growth developed at low initial stand densities. These low initial stand densities, probably the result of prolonged stand establishment, likely enabled height and crown size advantages among old and younger trees. Dominant and large codominant trees maintained live crown ratios and sustained diameter growth resulting in large stable trees indicated by low height-to-diameter ratios. The mean diameters of the dominant trees in the old-growth and the dominant trees in the young natural stands were not significantly different at age 40 and 100, indicating the young natural stands appear to be growing at the same rates as the old-growth in its first 100 years. The mean dominant diameters in the plantations and old-growth at age 40 and 100 were significantly different, indicating the plantations are growing and developing differently than young natural and old-growth forests. Plantations had grown rapidly for the first 20 to 30 years, and computer simulation indicated that a significant rapid decline in radial growth would occur between ages 30 and 55. Simulations also indicate that during this period, the mean diameters of the dominant plantation trees would fall below those of the old-growth in two of the three stands by age 85. Pre-commercial thinning 20 to 25 years ago in the plantations has helped sustain high early growth rates for a longer period of time than would have occurred if thinning had not been performed. Additional thinning in the future is likely needed to maintain rapid current rates. When simulated to age 250 both the young natural stands and the plantations maintained higher densities of smaller diameter trees than the old-growth stands. This simulation result indicates the possible inability of these stands to self-thin to the densities found in old-growth stands without some sort of density-reducing disturbance. The broad range of tree ages in the old-growth stands suggests that stand disturbances are a normal part of old-growth development on these sites. Five different plantation thinning options were also simulated to age 250, including additional options with thinning of understory trees and ingrowth. The projections indicate that when the plantations are left unthinned they would generally develop trees with small live crowns and mean diameters but still produce stable dominant overstory trees (low H:D ratios). Shade tolerant understory trees and ingrowth, such as western hemlock, are a key part of old-growth development. These trees may reduce the rate of growth and alter crown structure of the overstory trees over extended periods of time (200+ years). Additional thinning, possibly in multiple entries, in both the overstory and understory may be necessary for dense plantations to develop the tree size heterogeneity found in local old-growth forests. I also demonstrated a methodology to determine site-specific management targets or goals for creating old-growth structure from plantations. This was performed using past and current forest structure and composition information within a local landscape scale of 500 to 1000 acres, typical of the public land checkerboard ownership pattern. Stand types making up the historical landscape are identified and described retrospectively using historical and current aerial photographs and digital orthophotos, cruise records, previous studies, and sample plots of standing and harvested forests. The degree of detail provided through this methodology will likely help forest managers to define complex late-successional characteristics of stands and landscapes. My results indicate that stand and project area-specific definitions of old-growth and clearly defined goals for young stand management will facilitate development of old forest characteristics.
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567. [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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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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Rangelands span over 50% of the globe and approximately 70% of the United States. Although livestock production is an important use of rangelands, the benefits of rangelands are highly diverse. Humans ...
Citation Citation
- Title:
- Long-term Ecohydrologic Response to Western Juniper (Juniperus occidentalis) Control in Semiarid Watersheds of Central Oregon : A Paired Watershed Study
- Author:
- Ray, Grace L.
Rangelands span over 50% of the globe and approximately 70% of the United States. Although livestock production is an important use of rangelands, the benefits of rangelands are highly diverse. Humans find intrinsic value in protecting these unique and variable landscapes for wildlife, vegetation, and recreation enthusiasts. Woodland plant encroachment has become a major concern for land management agencies and private landowners across the United States and many rangeland communities worldwide. Studies around the world are characterizing the effect that woody species may have on ecologic and hydrologic function, as well as the potential consequences of prolonged encroachment. This research is an addition to a central Oregon paired watershed study that began in 1993 as way of characterizing ecohydrologic effects of western juniper (Juniperus occidentalis) removal. The overarching goals of the study presented here were to: 1) Characterize vegetation-soil water interactions at the landscape scale; 2) Analyze long-term soil water and groundwater fluctuations for treated versus untreated watersheds; 3) Asses subsurface flow connections between upland watersheds and a downstream valley. A landscape-scale assessment (2014 - 2015) of shallow soil water content, for to top 12-cm of the soil profile, across both watersheds indicated the treated watershed as having a significantly higher (P < 0.05) mean value of soil water content for three (July, January, and May) out of five measurement periods (July, November 2014 and January, March, May 2015). The untreated watershed was 2% higher in March 2015, and no significant difference was found between the two sites in November 2014. Analysis of the structure of canopy cover (i.e. juniper dominated versus juniper removed) using linear regression models found juniper cover to be correlated with decreasing soil water content for three of five months, with the exception of the wettest months of March and May, when juniper canopy was correlated with increases in soil water content. Soil textural properties were also analyzed as an independent variable in the linear models, and clay content was found to be correlated with increases in soil water content during the three wettest months (January, March, and May) across both watersheds. The long-term (2004 - 2015) analysis of groundwater level and deep soil water content fluctuations showed there to be distinct seasonal and storm-event responses. Groundwater levels in the untreated watershed consistently displayed higher yearly maximum values when compared to the treated, however, groundwater levels in the treated watershed persisted longer into the dry out period. Similar findings were reported in relation to long-term soil water content where the untreated watershed often displayed higher maximum responses but declined back to dry status sooner than the treated watershed. Both watersheds responded to seasonal and storm-event precipitation through soil water content fluctuations in the deep soil profile and through groundwater level fluctuations. Precipitation event responses could be observed on the order of hours for the treated watershed and on the order of days for the untreated. Antecedent soil water content seemed to play a large role in the effectiveness of the storm events. Summer precipitation had little influence on the deeper soil profile and on groundwater response. This may be due to dryer antecedent soil conditions and flashy overland flow. Water content in the top measured soil profile, however, increased and stayed at high levels for up to two weeks following a summer precipitation event which yielded approximately 27 mm of rainfall. Soil water and groundwater response were greatly influenced by winter precipitation events and pre-storm soil water conditions. The hydrologic connectivity of subsurface water flows, through fluctuations in deep soil water and groundwater levels, was found to be an important process in these watersheds. Temporary subsurface hydrologic connections were observed between upland and valley wells as the wet season progressed. This connection was supported by the results of a stable isotope analysis, which indicated that the origin of the water may be the same. This was concluded given the similar values of oxygen-18 found for both the treated and untreated upland sites and for valley groundwater monitoring locations. Large-scale juniper manipulation projects are taking place across the western United States and around the world. Many projects have the objectives of increasing water availability and stream flow to no avail. This research provides baseline data towards understanding the importance of the valuable subsurface water resources in landscapes with limited precipitation availability.
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First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations ...
Citation Citation
- Title:
- Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon
- Author:
- Arsan, E. Leyla
First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite introduction, have strengthened the process of science-based decision-making in aquatic animal health. In the case of M. cerebralis, it is necessary to use a risk assessment model with two unique segments that clearly address the distinct life stages and respective hosts of the parasite separately. The studies described examine the probability of M. cerebralis introduction and establishment for two regions: the state of Alaska, and the Willamette River basin, Oregon. The Alaska risk assessment was based on the assumption that the parasite did not already occur in the state. However, in the process of validating this assumption, we documented the first polymerase chain reaction (PCR) detection of the parasite in the state. The pathogen was identified in hatchery rainbow trout (Oncorhynchus mykiss) from the Anchorage area. Although this is the first detection of the parasite in Alaska, clinical whirling disease has never been documented in the state. To qualitatively assess the risk of further spread of M. cerebralis in Alaska, four potential routes of dissemination were examined: movement of fish by humans, natural dispersal (via migratory birds and stray anadromous salmon), recreational activities, and commercial seafood processing. This research indicates the most likely pathway for M. cerebralis transport in Alaska is human movement of fish. In the Willamette River basin, Oregon, introduction of M. cerebralis has already occurred, though establishment appears limited to a single private hatchery. Introduction in this region was considered the most likely to occur as a result of human movements of fish. Straying anadromous salmonids were also assessed and were present in higher numbers than predicted. However, they were not infected with the parasite, and thus the probability for introduction by this route is low. The probability of introduction of the parasite varies throughout the Willamette River basin. Areas with the highest probability for M. cerebralis introduction were identified as the Clackamas and Santiam River subbasins. The Clackamas River has already experienced an introduction of the parasite, has the largest concentration of hatcheries (state, federal, and private), has a popular sport fishery, and is the closest major tributary to the enormous piscivorous bird-populations in the Columbia River estuary. The Santiam subbasin has a popular sport fishery, received the highest number of stray fish in the Willamette River basin, and has the second largest concentration of hatcheries in the Willamette River basin. Unique from introduction, establishment of the parasite is dependent upon several environmental and biological factors including: water temperatures, spatial/temporal overlap of hosts, and the distribution and genetic composition of the parasite’s invertebrate host, Tubifex tubifex. The distribution, genetic composition and susceptibility of T. tubifex, were considered the most important factor in the ability of M. cerebralis to establish in both systems. Surveys of oligochaete populations were conducted in both study regions. In Alaska, T. tubifex was not detected from the southeast region and the apparent lack of appropriate tubificid hosts may prevent establishment in that part of the state. However, 4 lineages (I, III, IV, and VI) of the species were identified from southcentral Alaska. Lineage IV has not been previously been described in North America and its susceptibility to M. cerebralis was unknown. When lineage IV T. tubifex and 3 mixed-lineage (I, III, IV and VI) groups were exposed to M. cerebralis, only lineage III became infected under our experimental conditions. Thus, if the parasite were dispersed, conditions are appropriate for establishment and propagation of the parasite life cycle in southcentral Alaska, although detrimental effects on fish populations may be reduced as a result of the presence of non-susceptible lineages of T. tubifex. The probability of further establishment in this area is greatest in Ship Creek, where the abundance of susceptible T. tubifex, the presence of susceptible rainbow trout (Oncorhynchus mykiss), and the proximity to the known area of infection make conditions particularly appropriate. Similar to findings in Alaska, the Willamette River basin, Oregon also supports populations of susceptible T. tubifex. If the pathogen were introduced, probability of establishment is high in certain areas of the basin as all conditions are appropriate for propagation of the parasite life cycle. Tributaries to the mainstem Willamette River have the highest probability of establishment as these areas have the greatest numbers of susceptible T. tubifex. However, the abundance of resistant strains of T. tubifex could mitigate the effects of M. cerebralis if introduced. Management recommendations to reduce the likelihood of parasite dissemination are similar for Oregon and Alaska since human movement of fish and angler activities were considered the most likely routes of introduction for both regions. Based on this research, steps should also be taken to limit human movement of fish, whether by restricting carcass planting for stream enrichment in Oregon, or by prohibiting use of fish heads as bait in southcentral Alaska. The states should also allot resources to angler education and awareness of the effects of angler activity and recreation on dispersal of M. cerebralis. This could be done using a combination of brochures and signage at boat ramps describing how to prevent spread of aquatic nuisance species.