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• 1. [Article] A historical reconstruction and land use history of six tidal wetlands in Oregon

  Citation × Citation Citation Abstract Copy Title: A historical reconstruction and land use history of six tidal wetlands in Oregon Author: Hennessey, Jennifer Taylor Title: A historical reconstruction and land use history of six tidal wetlands in Oregon Author: Hennessey, Jennifer Taylor Close

• 2. [Article] A land use history of Benton County, Oregon

  Citation × Citation Citation Abstract Copy Title: A land use history of Benton County, Oregon Author: Longwood, Franklin Russell Title: A land use history of Benton County, Oregon Author: Longwood, Franklin Russell Close

• 3. [Article] Warming and earlier spring increase western U.S. forest wildfire activity

  Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes ...

  Citation × Citation Citation Abstract Copy Title: Warming and earlier spring increase western U.S. forest wildfire activity Author: Swetnam, T.W., Cayan, D.R., Westerling, A.L., Hidalgo, H.G. Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19thand 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt. Title: Warming and earlier spring increase western U.S. forest wildfire activity Author: Swetnam, T.W., Cayan, D.R., Westerling, A.L., Hidalgo, H.G. Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19thand 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt. Close

• 4. [Article] Warming and earlier spring increase western U.S. forest wildfire activity

  Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes ...

  Citation × Citation Citation Abstract Copy Title: Warming and earlier spring increase western U.S. forest wildfire activity Author: Cayan, D. R., Westerling, A. L., Swetnam, T. W., Hidalgo, H. G. Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19th- and 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt. Title: Warming and earlier spring increase western U.S. forest wildfire activity Author: Cayan, D. R., Westerling, A. L., Swetnam, T. W., Hidalgo, H. G. Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19th- and 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt. Close

• 5. [Article] Historical changes in stream habitats in the Columbia River basin

  Knowledge of how stream habitats change over time in natural and human-influenced ecosystems at large, regional scales is currently limited. A historical stream survey (1934-1945) was compared to current ...

  Citation × Citation Citation Abstract Copy Title: Historical changes in stream habitats in the Columbia River basin Author: McIntosh, Bruce A. Knowledge of how stream habitats change over time in natural and human-influenced ecosystems at large, regional scales is currently limited. A historical stream survey (1934-1945) was compared to current surveys to assess changes in poo1 habitats in the Columbia River basin. Streams from across the basin, representing a wide range of geologies, stream sizes and land-use histories, were used to evaluate habitat change. We classified streams as managed or unmanaged, based on their land-use histories. Managed basins were watersheds managed predominantly for multiple-use (e.g., timber harvest, livestock grazing) and unmanaged basins were minimally affected by human disturbance (e.g., wilderness/roadless areas). The quantity and quality of pool habitats increased or remained the same in unmanaged streams, and decreased in managed streams since the 1930s. Despite differences in stream size and land-use history, the magnitude and direction of theses changes were consistent. In addition, the decrease in pool habitats did not differ between public and private lands. Ecoregions were used to assess regional patterns to these changes. Our analysis showed that pool habitats decreased in all Ecoregions except the North Cascades Ecoregion. Regional land-use histories were documented for the study streams. The overgrazing of most rangelands had been documented by 1900. Grazing practices began to change after 1930, but current information suggests that while uplands have improved, riparian areas have not. By World War II, stream habitats had been affected by the loss of riparian vegetation, large woody debris, and aquatic habitats due to splash dams, log drives, and riparian timber harvest. Timber harvest expanded to the uplands after World War II, as the demand for timber expanded. Rapidly developing road networks increased runoff and sedimentation, which continued the impact of timber harvest on already damaged stream ecosystems. Almost 90% of managed streams had roads along the channel or within the floodplain. "Stream improvements," such as channelization and stream cleaning, also affected stream ecosystems. We concluded that the chronic and persistent effects of land-use practices had simplified stream channels and reduced habitat complexity in most managed watersheds in the Columbia River basin. Title: Historical changes in stream habitats in the Columbia River basin Author: McIntosh, Bruce A. Knowledge of how stream habitats change over time in natural and human-influenced ecosystems at large, regional scales is currently limited. A historical stream survey (1934-1945) was compared to current surveys to assess changes in poo1 habitats in the Columbia River basin. Streams from across the basin, representing a wide range of geologies, stream sizes and land-use histories, were used to evaluate habitat change. We classified streams as managed or unmanaged, based on their land-use histories. Managed basins were watersheds managed predominantly for multiple-use (e.g., timber harvest, livestock grazing) and unmanaged basins were minimally affected by human disturbance (e.g., wilderness/roadless areas). The quantity and quality of pool habitats increased or remained the same in unmanaged streams, and decreased in managed streams since the 1930s. Despite differences in stream size and land-use history, the magnitude and direction of theses changes were consistent. In addition, the decrease in pool habitats did not differ between public and private lands. Ecoregions were used to assess regional patterns to these changes. Our analysis showed that pool habitats decreased in all Ecoregions except the North Cascades Ecoregion. Regional land-use histories were documented for the study streams. The overgrazing of most rangelands had been documented by 1900. Grazing practices began to change after 1930, but current information suggests that while uplands have improved, riparian areas have not. By World War II, stream habitats had been affected by the loss of riparian vegetation, large woody debris, and aquatic habitats due to splash dams, log drives, and riparian timber harvest. Timber harvest expanded to the uplands after World War II, as the demand for timber expanded. Rapidly developing road networks increased runoff and sedimentation, which continued the impact of timber harvest on already damaged stream ecosystems. Almost 90% of managed streams had roads along the channel or within the floodplain. "Stream improvements," such as channelization and stream cleaning, also affected stream ecosystems. We concluded that the chronic and persistent effects of land-use practices had simplified stream channels and reduced habitat complexity in most managed watersheds in the Columbia River basin. Close

• 6. [Article] Mason’s Run brook trout (Salvelinus fontinalis): history, management challenges, and recommendations

  Graduation date: 2016

  Citation × Citation Citation Abstract Copy Title: Mason’s Run brook trout (Salvelinus fontinalis): history, management challenges, and recommendations Author: Russell, Joseph D. III Graduation date: 2016 Title: Mason’s Run brook trout (Salvelinus fontinalis): history, management challenges, and recommendations Author: Russell, Joseph D. III Graduation date: 2016 Close

• 7. [Article] Effects of deforestation and land use on biomass, carbon, and nutrient pools in the Los Tuxtlas Region, Mexico

  Land-use change in forested regions of the tropics is currently one of the largest anthropogenic perturbations on earth; it is a force capable of altering biogeochemical cycles at local, regional, and ...

  Citation × Citation Citation Abstract Copy Title: Effects of deforestation and land use on biomass, carbon, and nutrient pools in the Los Tuxtlas Region, Mexico Author: Hughes, R. Flint Land-use change in forested regions of the tropics is currently one of the largest anthropogenic perturbations on earth; it is a force capable of altering biogeochemical cycles at local, regional, and global scales. However, significant uncertainties exist concerning the impact of land-use change on biomass and elemental pools of tropical forests. To evaluate the response of biomass and elemental pools to deforestation and land-use in the Los Tuxtlas Region, Mexico, total aboveground biomass (TAGB), C, N, S, and P pools were quantified along a land-use gradient that included primary forests, pastures, cornfields, and secondary forests. TAGB of primary forests averaged 403 Mg/ha; pastures and cornfields averaged 24 and 23 Mg/ha, respectively. Conversion of primary forests to pastures or cornfields resulted in declines of 94% of aboveground C pools, 92% of aboveground N, 83% of aboveground P, and between 89% and 95% of aboveground S. Soil pools of C, N, and S did not differ significantly between primary forests, pastures, and cornfields. Soil C to a 1 m depth ranged from 166-210 Mg/ha; N and S ranged from 16,O00-2O,000 kg/ha and 340O-38OO kg/ha, respectively. In secondary forests, TAGB increased with increasing forest age; accumulations ranged from 4.8 Mg/ha in a 6-month- old site to 287 Mg/ha in a 50-year-old site. Results indicate that secondary forests will attain the equivalent of primary forest TAGB in 73 years. However, rates of TAGB accumulation were constrained by land-use history; rates decreased with increasing duration of land use prior to abandonment. Soil pools of secondary forests were not correlated to forest age or prior land-use history and did not differ significantly from soil pools of primary forests, pastures, or cornfields. As a group, soils of primary and old secondary forest sites had significantly larger pools of available N and higher rates of nitrification and N mineralization than the combined group of pastures, cornfields, and recently abandoned sites. Currently, the Los Tuxtias Region functions as a net source of greenhouse gases. Regenerating secondary forests have the capacity to counterbalance emissions resulting from deforestation, but presently constitute only a small percentage of the the regional landscape. Title: Effects of deforestation and land use on biomass, carbon, and nutrient pools in the Los Tuxtlas Region, Mexico Author: Hughes, R. Flint Land-use change in forested regions of the tropics is currently one of the largest anthropogenic perturbations on earth; it is a force capable of altering biogeochemical cycles at local, regional, and global scales. However, significant uncertainties exist concerning the impact of land-use change on biomass and elemental pools of tropical forests. To evaluate the response of biomass and elemental pools to deforestation and land-use in the Los Tuxtlas Region, Mexico, total aboveground biomass (TAGB), C, N, S, and P pools were quantified along a land-use gradient that included primary forests, pastures, cornfields, and secondary forests. TAGB of primary forests averaged 403 Mg/ha; pastures and cornfields averaged 24 and 23 Mg/ha, respectively. Conversion of primary forests to pastures or cornfields resulted in declines of 94% of aboveground C pools, 92% of aboveground N, 83% of aboveground P, and between 89% and 95% of aboveground S. Soil pools of C, N, and S did not differ significantly between primary forests, pastures, and cornfields. Soil C to a 1 m depth ranged from 166-210 Mg/ha; N and S ranged from 16,O00-2O,000 kg/ha and 340O-38OO kg/ha, respectively. In secondary forests, TAGB increased with increasing forest age; accumulations ranged from 4.8 Mg/ha in a 6-month- old site to 287 Mg/ha in a 50-year-old site. Results indicate that secondary forests will attain the equivalent of primary forest TAGB in 73 years. However, rates of TAGB accumulation were constrained by land-use history; rates decreased with increasing duration of land use prior to abandonment. Soil pools of secondary forests were not correlated to forest age or prior land-use history and did not differ significantly from soil pools of primary forests, pastures, or cornfields. As a group, soils of primary and old secondary forest sites had significantly larger pools of available N and higher rates of nitrification and N mineralization than the combined group of pastures, cornfields, and recently abandoned sites. Currently, the Los Tuxtias Region functions as a net source of greenhouse gases. Regenerating secondary forests have the capacity to counterbalance emissions resulting from deforestation, but presently constitute only a small percentage of the the regional landscape. Close

• 8. [Article] Oregon Explorer : Natural resources information for current and future decision-makers

  Oregon Explorer (www.oregonexplorer.info), a natural resources digital library developed by Oregon State University Libraries and the Institute for Natural Resources, was created for Oregon’s natural resource ...

  Citation × Citation Citation Abstract Copy Title: Oregon Explorer : Natural resources information for current and future decision-makers Author: Salwasser, Janine, Wirth, Andrea A. Oregon Explorer (www.oregonexplorer.info), a natural resources digital library developed by Oregon State University Libraries and the Institute for Natural Resources, was created for Oregon’s natural resource decision-makers to promote informed and streamlined public and private decision-making. Examples of projects and successes of the Oregon Explorer include a basin portal for the Umpqua River, developed in conjunction with the Partnership for Umpqua Rivers, as well as topic portals, such as the Land Use Explorer launched in October 2007 to inform Oregonians about land use history and current issues. We have learned that in the natural resources arena, user needs change with different geographies, yet the adaptations made at the local level are useful in expanding the content and services delivered at the statewide level. It is not enough to just provide access to data or documents. Users want access to a wide variety of integrated information resources—digital documents, interactive maps and reports, decision support, high resolution imagery, and access to available expertise. With Oregon Explorer becoming established as a tool for decision-makers and citizens, members of the team are exploring opportunities to use the digital library in classroom settings. Students in Oregon’s K-12 schools and OSU’s undergraduates are groups that we feel could benefit from the natural resources information and tools available. Proposals are being developed to extend Oregon Explorer’s capabilities for use in primary and secondary education. Oregon Explorer is being used in several university classrooms and will become more integrated as the content and tools grow and as strategies for further incorporation are developed. This evolving natural resources digital library will enable current and future decision-makers to learn about Oregon's environment and to actively engage in creating and sharing knowledge before decisions are made. Title: Oregon Explorer : Natural resources information for current and future decision-makers Author: Salwasser, Janine, Wirth, Andrea A. Oregon Explorer (www.oregonexplorer.info), a natural resources digital library developed by Oregon State University Libraries and the Institute for Natural Resources, was created for Oregon’s natural resource decision-makers to promote informed and streamlined public and private decision-making. Examples of projects and successes of the Oregon Explorer include a basin portal for the Umpqua River, developed in conjunction with the Partnership for Umpqua Rivers, as well as topic portals, such as the Land Use Explorer launched in October 2007 to inform Oregonians about land use history and current issues. We have learned that in the natural resources arena, user needs change with different geographies, yet the adaptations made at the local level are useful in expanding the content and services delivered at the statewide level. It is not enough to just provide access to data or documents. Users want access to a wide variety of integrated information resources—digital documents, interactive maps and reports, decision support, high resolution imagery, and access to available expertise. With Oregon Explorer becoming established as a tool for decision-makers and citizens, members of the team are exploring opportunities to use the digital library in classroom settings. Students in Oregon’s K-12 schools and OSU’s undergraduates are groups that we feel could benefit from the natural resources information and tools available. Proposals are being developed to extend Oregon Explorer’s capabilities for use in primary and secondary education. Oregon Explorer is being used in several university classrooms and will become more integrated as the content and tools grow and as strategies for further incorporation are developed. This evolving natural resources digital library will enable current and future decision-makers to learn about Oregon's environment and to actively engage in creating and sharing knowledge before decisions are made. Close

• 9. [Article] Mesoscale Variation in Snag and Hardwood Densities and Sizes in Old-Growth Forests in Western Oregon

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Society ...

  Citation × Citation Citation Abstract Copy Title: Mesoscale Variation in Snag and Hardwood Densities and Sizes in Old-Growth Forests in Western Oregon Author: Bright, Cheryl, Puettmann, Klaus, Ares, Adrian To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Society of American Foresters and can be found at: http://www.safnet.org/. Title: Mesoscale Variation in Snag and Hardwood Densities and Sizes in Old-Growth Forests in Western Oregon Author: Bright, Cheryl, Puettmann, Klaus, Ares, Adrian To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Society of American Foresters and can be found at: http://www.safnet.org/. Close

• 10. [Article] Hydrologic and Land Cover Effects on Sources and Fate of In-Stream Fluorescent Dissolved Organic Matter

  Dissolved organic matter (DOM) is a critical component of the carbon cycle linking terrestrial and aquatic ecosystems. Although many factors influence DOM fluxes and quality in rivers, controls on DOM ...

  Citation × Citation Citation Abstract Copy Title: Hydrologic and Land Cover Effects on Sources and Fate of In-Stream Fluorescent Dissolved Organic Matter Author: Lee, Baek Soo P. Dissolved organic matter (DOM) is a critical component of the carbon cycle linking terrestrial and aquatic ecosystems. Although many factors influence DOM fluxes and quality in rivers, controls on DOM compositions in catchments of the western U.S. are poorly understood. UV and fluorescent spectroscopy is a simpler, faster, and less expensive DOM fingerprinting technique compared to techniques, such as nuclear magnetic resonance (NMR) spectroscopy or wet chemical fractionation, and could be useful for characterizing complex DOM chemistry. However, only 1 % of DOM is estimated to be fluorescent, and the utility of UV and fluorescent spectroscopy for DOM characterization needs to be further investigated. This dissertation applied UV and fluorescent spectroscopy to examine hydrologic and land cover controls on DOM chemistry in streams of 45 catchments in the forested headwaters and a mixed landscape of the Willamette River Basin, Oregon, based on two years of monitoring. This dissertation contributes three major findings. First, freezing of water alters DOM chemistry by preferentially precipitating aromatic DOM. Second, UV and fluorescent spectroscopy was able to discriminate DOM delivered from highly processed, proteinrich deep subsurface sources during dry seasons especially in forested headwater streams of the H. J. Andrews Experimental Forest (HJA), where nitrogen inputs are very low. In addition, fluorescent DOM chemistry differed among watersheds with varying forest management history. Third, although fluorescent DOM in a headwater forested system differed among land use history, fluorescent DOM composition did not vary among streams draining a well-mixed landscape of urban, pasture/hay, forest, and agricultural land cover types in the central Willamette River Basin, where nitrogen inputs to streams are relatively high. Dissolved organic carbon (DOC) concentration decreased and the fluorescent index indicated an increase in terrestrial sources of DOM from small (1st and 2nd order) to large (4th to 6th order) streams. A protein-like DOM component that was detected in the headwater forested study site (HJA) was not detected in stream samples from the middle basin study site. These findings indicate that in-stream respiration, fueled by nutrient additions from agriculture runoff, consumes bioavailable, labile DOM (proteins) preferentially relative to more recalcitrant, terrestrial sources of DOM along water flow paths from headwater streams to major rivers. This study shows the clear applicability of the fluorescent characterization of DOM in identifying hydrologic and landscape controls as well as varying DOM chemistry and functions throughout watershed ecosystems. Title: Hydrologic and Land Cover Effects on Sources and Fate of In-Stream Fluorescent Dissolved Organic Matter Author: Lee, Baek Soo P. Dissolved organic matter (DOM) is a critical component of the carbon cycle linking terrestrial and aquatic ecosystems. Although many factors influence DOM fluxes and quality in rivers, controls on DOM compositions in catchments of the western U.S. are poorly understood. UV and fluorescent spectroscopy is a simpler, faster, and less expensive DOM fingerprinting technique compared to techniques, such as nuclear magnetic resonance (NMR) spectroscopy or wet chemical fractionation, and could be useful for characterizing complex DOM chemistry. However, only 1 % of DOM is estimated to be fluorescent, and the utility of UV and fluorescent spectroscopy for DOM characterization needs to be further investigated. This dissertation applied UV and fluorescent spectroscopy to examine hydrologic and land cover controls on DOM chemistry in streams of 45 catchments in the forested headwaters and a mixed landscape of the Willamette River Basin, Oregon, based on two years of monitoring. This dissertation contributes three major findings. First, freezing of water alters DOM chemistry by preferentially precipitating aromatic DOM. Second, UV and fluorescent spectroscopy was able to discriminate DOM delivered from highly processed, proteinrich deep subsurface sources during dry seasons especially in forested headwater streams of the H. J. Andrews Experimental Forest (HJA), where nitrogen inputs are very low. In addition, fluorescent DOM chemistry differed among watersheds with varying forest management history. Third, although fluorescent DOM in a headwater forested system differed among land use history, fluorescent DOM composition did not vary among streams draining a well-mixed landscape of urban, pasture/hay, forest, and agricultural land cover types in the central Willamette River Basin, where nitrogen inputs to streams are relatively high. Dissolved organic carbon (DOC) concentration decreased and the fluorescent index indicated an increase in terrestrial sources of DOM from small (1st and 2nd order) to large (4th to 6th order) streams. A protein-like DOM component that was detected in the headwater forested study site (HJA) was not detected in stream samples from the middle basin study site. These findings indicate that in-stream respiration, fueled by nutrient additions from agriculture runoff, consumes bioavailable, labile DOM (proteins) preferentially relative to more recalcitrant, terrestrial sources of DOM along water flow paths from headwater streams to major rivers. This study shows the clear applicability of the fluorescent characterization of DOM in identifying hydrologic and landscape controls as well as varying DOM chemistry and functions throughout watershed ecosystems. Close

• 11. [Article] Response of soil microbial communities to physical and chemical disturbances: implications for soil quality and land use sustainability

  The objectives of this thesis were to evaluate the responses of soil microbial communities to physical and chemical disturbances, and associate these responses with soil functional stability and changes ...

  Citation × Citation Citation Abstract Copy Title: Response of soil microbial communities to physical and chemical disturbances: implications for soil quality and land use sustainability Author: Chaer, Guilherme M. The objectives of this thesis were to evaluate the responses of soil microbial communities to physical and chemical disturbances, and associate these responses with soil functional stability and changes in soil quality. The first study consisted of application of heat shocks (HS) to soils with contrasting land use history to evaluate differences in the stability of soil enzymes (laccase, cellulase and fluorescein diacetate hydrolysis) and microbial community composition as determined by phospholipid fatty acid (PLFA) analysis. The conversion of land use from forest to agriculture resulted in a new microbial community that was less functionally stable. Loss of stability was indicated by the reduced resilience of laccase and cellulase activities in the agricultural soil, which suggested a less diverse community of microorganisms capable of producing these enzymes. The second study examined changes in microbial community composition and diversity that occurred across a gradient of soil disturbance. Disturbances were simulated by tillage events applied at different intensities to a 12-year-old fallow area. These treatments caused degradation of several soil physico-chemical properties, and alterations in microbial structure based on PLFA and terminal restriction fragment length polymorphism (T-RFLP) analyses, and in metabolic potential based on community level physiological profiles (CLPPs). Multivariate ordination of soil properties revealed the formation of a linear gradient of soil degradation that was significantly correlated with CLPPs, but not with T-RFLP and PLFA profiles. Nevertheless, changes observed in microbial community structure were significantly associated with decreases in soil organic C and field hydraulic conductivity. The third study demonstrated that undisturbed forest soils from western Oregon express an equilibrium between soil organic matter and biochemical properties. A model fitted through multiple regression analysis showed that phosphatase activity and microbial biomass were able to explain 97% of the soil organic C in these soils. This equilibrium was disrupted when a soil from an old-growth site was submitted to chemical stresses (Cu addition or pH alteration) and physical disturbances (wet-dry or freeze-thaw cycles). The magnitude of this disruption was consistently expressed by the ratio between soil C predicted by the model (Cp), and soil C that was measured (Cm). This ratio is proposed as biochemically-based index of soil quality. Title: Response of soil microbial communities to physical and chemical disturbances: implications for soil quality and land use sustainability Author: Chaer, Guilherme M. The objectives of this thesis were to evaluate the responses of soil microbial communities to physical and chemical disturbances, and associate these responses with soil functional stability and changes in soil quality. The first study consisted of application of heat shocks (HS) to soils with contrasting land use history to evaluate differences in the stability of soil enzymes (laccase, cellulase and fluorescein diacetate hydrolysis) and microbial community composition as determined by phospholipid fatty acid (PLFA) analysis. The conversion of land use from forest to agriculture resulted in a new microbial community that was less functionally stable. Loss of stability was indicated by the reduced resilience of laccase and cellulase activities in the agricultural soil, which suggested a less diverse community of microorganisms capable of producing these enzymes. The second study examined changes in microbial community composition and diversity that occurred across a gradient of soil disturbance. Disturbances were simulated by tillage events applied at different intensities to a 12-year-old fallow area. These treatments caused degradation of several soil physico-chemical properties, and alterations in microbial structure based on PLFA and terminal restriction fragment length polymorphism (T-RFLP) analyses, and in metabolic potential based on community level physiological profiles (CLPPs). Multivariate ordination of soil properties revealed the formation of a linear gradient of soil degradation that was significantly correlated with CLPPs, but not with T-RFLP and PLFA profiles. Nevertheless, changes observed in microbial community structure were significantly associated with decreases in soil organic C and field hydraulic conductivity. The third study demonstrated that undisturbed forest soils from western Oregon express an equilibrium between soil organic matter and biochemical properties. A model fitted through multiple regression analysis showed that phosphatase activity and microbial biomass were able to explain 97% of the soil organic C in these soils. This equilibrium was disrupted when a soil from an old-growth site was submitted to chemical stresses (Cu addition or pH alteration) and physical disturbances (wet-dry or freeze-thaw cycles). The magnitude of this disruption was consistently expressed by the ratio between soil C predicted by the model (Cp), and soil C that was measured (Cm). This ratio is proposed as biochemically-based index of soil quality. Close

• 12. [Article] Environmental variables as predictors of fish assemblages in the Tillamook Basin, Oregon

  The Tillamook and Kilchis subbasins of the Tillamook Bay watershed (Oregon Coast Range) have differences in geology and land use history and, therefore, varied environmental conditions that could affect ...

  Citation × Citation Citation Abstract Copy Title: Environmental variables as predictors of fish assemblages in the Tillamook Basin, Oregon Author: Rose, Cathleen E. The Tillamook and Kilchis subbasins of the Tillamook Bay watershed (Oregon Coast Range) have differences in geology and land use history and, therefore, varied environmental conditions that could affect fish assemblages. Fifty-two randomly selected wadeable stream reaches in these two subbasins were surveyed for stream habitat and fish assemblage composition during two summer field seasons. Data collected were used to identify environmental variables most associated with fish assemblages, determine major predictors of fish species relative abundance, and test for any differences in fish assemblages between the Tillamook and Kilchis subbasins and among three stream orders. Eleven fish species were encountered, including four salmonid species (Oncorhynchus spp.) and five species of sculpin (Cottus spp.). For three sites visited twice in both field seasons, variability in fish assemblages and environmental measurements between sample years and between early and late-summer visits to sites was low. Fish assemblages differed between the two subbasins. The assemblages in the Kilchis subbasin contained higher proportions of trout species, while the Tillamook subbasin assemblages contained higher proportions of sculpin species. A breakdown of fish assemblages by stream order showed that different fish species dominated the assemblages in different sized streams. With data from both subbasins combined, trout species composed a smaller proportion of the fish assemblages in larger streams, and sculpin species composition also varied with stream order. Results from non-metric multidimensional scaling ordinations indicated that substrate type, stream gradient, and variables related to stream size were the most highly correlated to fish species relative abundances. Multiple linear regression was used to assess the usefulness of an uncorrelated subset of the environmental variables as predictors of relative abundance of the six most common fish species. The environmental variables were good predictors of relative abundance for some species, but were less successful in predicting abundances of entirely anadromous species. These results provide valuable insight into fish-habitat relationships using a fish assemblage perspective and incorporating species, such as sculpins, for which there is little existing information. There has been recent interest in quantifying the effects of human land use on stream fish, and these data can be used in future studies to explore potential links between important environmental variables and land use practices. Title: Environmental variables as predictors of fish assemblages in the Tillamook Basin, Oregon Author: Rose, Cathleen E. The Tillamook and Kilchis subbasins of the Tillamook Bay watershed (Oregon Coast Range) have differences in geology and land use history and, therefore, varied environmental conditions that could affect fish assemblages. Fifty-two randomly selected wadeable stream reaches in these two subbasins were surveyed for stream habitat and fish assemblage composition during two summer field seasons. Data collected were used to identify environmental variables most associated with fish assemblages, determine major predictors of fish species relative abundance, and test for any differences in fish assemblages between the Tillamook and Kilchis subbasins and among three stream orders. Eleven fish species were encountered, including four salmonid species (Oncorhynchus spp.) and five species of sculpin (Cottus spp.). For three sites visited twice in both field seasons, variability in fish assemblages and environmental measurements between sample years and between early and late-summer visits to sites was low. Fish assemblages differed between the two subbasins. The assemblages in the Kilchis subbasin contained higher proportions of trout species, while the Tillamook subbasin assemblages contained higher proportions of sculpin species. A breakdown of fish assemblages by stream order showed that different fish species dominated the assemblages in different sized streams. With data from both subbasins combined, trout species composed a smaller proportion of the fish assemblages in larger streams, and sculpin species composition also varied with stream order. Results from non-metric multidimensional scaling ordinations indicated that substrate type, stream gradient, and variables related to stream size were the most highly correlated to fish species relative abundances. Multiple linear regression was used to assess the usefulness of an uncorrelated subset of the environmental variables as predictors of relative abundance of the six most common fish species. The environmental variables were good predictors of relative abundance for some species, but were less successful in predicting abundances of entirely anadromous species. These results provide valuable insight into fish-habitat relationships using a fish assemblage perspective and incorporating species, such as sculpins, for which there is little existing information. There has been recent interest in quantifying the effects of human land use on stream fish, and these data can be used in future studies to explore potential links between important environmental variables and land use practices. Close

• 13. [Article] Seed and establishment limitation contribute to long-term native forb declines in California grasslands

  This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://www.esa.org/.

  Citation × Citation Citation Abstract Copy Title: Seed and establishment limitation contribute to long-term native forb declines in California grasslands Author: Brandt, Angela J., Seabloom, Eric W. This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://www.esa.org/. Title: Seed and establishment limitation contribute to long-term native forb declines in California grasslands Author: Brandt, Angela J., Seabloom, Eric W. This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://www.esa.org/. Close

• 14. [Article] Trends in cation, nitrogen, sulfate and hydrogen ion concentrations in precipitation in the United States and Europe from 1978 to 2010: a new look at an old problem

  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/10533.

  Citation × Citation Citation Abstract Copy Title: Trends in cation, nitrogen, sulfate and hydrogen ion concentrations in precipitation in the United States and Europe from 1978 to 2010: a new look at an old problem Author: Lajtha, Kate, Jones, Julia 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/10533. Title: Trends in cation, nitrogen, sulfate and hydrogen ion concentrations in precipitation in the United States and Europe from 1978 to 2010: a new look at an old problem Author: Lajtha, Kate, Jones, Julia 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/10533. Close

• 15. [Article] The roles of provenance and phylogeny in recruitment, community assembly, and species coexistence in invaded California grasslands

  Biological invasions pose one of the greatest threats to global biodiversity, but many naturalized invaders coexist with the native community. Community ecology theory provides a framework for understanding ...

  Citation × Citation Citation Abstract Copy Title: The roles of provenance and phylogeny in recruitment, community assembly, and species coexistence in invaded California grasslands Author: Brandt, Angela J. Biological invasions pose one of the greatest threats to global biodiversity, but many naturalized invaders coexist with the native community. Community ecology theory provides a framework for understanding the mechanisms by which invaders might coexist with native species or exclude them from the community, thus informing management practices to maximize their effectiveness at conserving native biodiversity. Differences in functional or phylogenetic similarity of invaders to native residents can affect invasion success and the probability they will coexist with natives. For example, functionally dissimilar species may not compete strongly and distantly related species may share fewer natural enemies. Furthermore, environmental heterogeneity can promote species coexistence by providing the opportunity for a greater number of coexistence mechanisms to operate, thereby mitigating the potential for species invasions to lead to native extinction. My thesis examines how provenance (i.e., native origin) and phylogenetic relatedness of plant species affect community dynamics and species interactions in the invaded California grasslands. To do this I have assembled two unique community data sets, one spanning 48 years across a 1000-ha site and one spanning 7 years along a 500-km latitudinal transect. I show that native and exotic species abundance and diversity is highly variable in both time and space, but these provenance group responses are rarely negatively correlated (Chapter 2). Thus, exotic species do not generally appear to exclude natives from communities. Long-term abundance patterns further suggest that the system remains in a state of transience, and populations of several native species are declining at local scales (Chapter 3). Recruitment limitation due to the build-up of plant litter associated with exotic grasses may be generally responsible for these declines, but habitat suitability, land-use history, and community composition also affect native recruitment. Across the grasslands, disturbance and resource supply can interact to affect both species and phylogenetic diversity (Chapter 4). Disturbance in particular can increase diversity, likely by increasing opportunities for colonization by removing plant litter that previously limited recruitment. Both phylogeny and provenance can also affect biotic interactions, such as with communities of soil organisms (Chapter 5). Thus, I have shown that spatio-temporal heterogeneity, alterations to the biotic environment mediated by exotic invasion, and phylogenetic relationships among species are all important considerations when evaluating impacts of invasion and designing management strategies to conserve native biodiversity, especially in light of anthropogenic influence on disturbance regimes and resource supply. Title: The roles of provenance and phylogeny in recruitment, community assembly, and species coexistence in invaded California grasslands Author: Brandt, Angela J. Biological invasions pose one of the greatest threats to global biodiversity, but many naturalized invaders coexist with the native community. Community ecology theory provides a framework for understanding the mechanisms by which invaders might coexist with native species or exclude them from the community, thus informing management practices to maximize their effectiveness at conserving native biodiversity. Differences in functional or phylogenetic similarity of invaders to native residents can affect invasion success and the probability they will coexist with natives. For example, functionally dissimilar species may not compete strongly and distantly related species may share fewer natural enemies. Furthermore, environmental heterogeneity can promote species coexistence by providing the opportunity for a greater number of coexistence mechanisms to operate, thereby mitigating the potential for species invasions to lead to native extinction. My thesis examines how provenance (i.e., native origin) and phylogenetic relatedness of plant species affect community dynamics and species interactions in the invaded California grasslands. To do this I have assembled two unique community data sets, one spanning 48 years across a 1000-ha site and one spanning 7 years along a 500-km latitudinal transect. I show that native and exotic species abundance and diversity is highly variable in both time and space, but these provenance group responses are rarely negatively correlated (Chapter 2). Thus, exotic species do not generally appear to exclude natives from communities. Long-term abundance patterns further suggest that the system remains in a state of transience, and populations of several native species are declining at local scales (Chapter 3). Recruitment limitation due to the build-up of plant litter associated with exotic grasses may be generally responsible for these declines, but habitat suitability, land-use history, and community composition also affect native recruitment. Across the grasslands, disturbance and resource supply can interact to affect both species and phylogenetic diversity (Chapter 4). Disturbance in particular can increase diversity, likely by increasing opportunities for colonization by removing plant litter that previously limited recruitment. Both phylogeny and provenance can also affect biotic interactions, such as with communities of soil organisms (Chapter 5). Thus, I have shown that spatio-temporal heterogeneity, alterations to the biotic environment mediated by exotic invasion, and phylogenetic relationships among species are all important considerations when evaluating impacts of invasion and designing management strategies to conserve native biodiversity, especially in light of anthropogenic influence on disturbance regimes and resource supply. Close

• 16. [Article] Meadow classification in the Willamette National Forest and conifer encroachment patterns in the Chucksney-Grasshopper meadow complex, Western Cascade Range, Oregon

  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 Citation Abstract Copy 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. 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. Close

• 17. [Article] Studies to facilitate reintroduction of golden paintbrush (Castilleja levisecta) to the Willamette Valley, Oregon

  Golden paintbrush (Castilleja levisecta Greenman) historically inhabited the prairies of the Willamette Valley, Oregon. However, this Pacific Northwest endemic is currently restricted to eleven sites in ...

  Citation × Citation Citation Abstract Copy Title: Studies to facilitate reintroduction of golden paintbrush (Castilleja levisecta) to the Willamette Valley, Oregon Author: Lawrence, Beth A. Golden paintbrush (Castilleja levisecta Greenman) historically inhabited the prairies of the Willamette Valley, Oregon. However, this Pacific Northwest endemic is currently restricted to eleven sites in the Puget Trough of Washington and British Columbia. Recovery criteria call for the establishment of new populations throughout the species historic range, including the Willamette Valley. In order to facilitate reintroduction to this region, we examined: (1) habitat characteristics of potential C. levisecta recovery sites in the Willamette Valley and compared them to remaining populations in the Puget Trough, (2) a suite of ecological and genetic factors likely to contribute to reintroduction success using common garden experiments, and (3) how the performance of this rare hemiparasite was affected by the availability of different host combinations in the greenhouse and in the field. Potential C. levisecta reintroduction sites in the Willamette Valley had distinct vegetation communities and soil characteristics compared with remaining populations in the Puget Trough. This disparity was likely related to regional differences in geology, climate, ocean proximity, and land-use history. Many of the species indicative of remaining populations in the Puget Trough were native pereimials, while those of potential reintroduction sites in the Willamette Valley were introduced annuals. Soil characteristics of C. levisecta sites were also distinct among the two ecoregions. Puget Trough sites were located on sandy soils with generally high levels of magnesium and sulfur, while Willamette Valley sites were found on silty-clay soils with high concentrations of potassium and phosphorous. Differences in soil texture, and magnesium and potassium concentrations were associated with plant community divergence among the two regions. Decisions regarding seed source and recovery site selection are especially difficult in portions of a species range that are uninhabited, as no reference populations exist with which to compare ecological information. Using common garden experiments, we tested hypotheses about how C. levisecta transplants would perform in relation to the ecological similarity between seed source and introduction site, the effective population size and genetic diversity of seed sources, and the habitat quality of the recovery site. We observed significant variation in performance measures among source populations and common garden sites. Plant community characteristics, including the abundance of nonnative species and the similarity in community structure between source populations and common garden sites, helped explain the variation in these performance measures. Exotic species cover at common garden sites was associated with a reduction in performance of first year C. levisecta transplants. Survival of second year transplants increased with increasing similarity in plant functional groups between source and common garden sites, supporting the idea of a "home-habitat advantage." These results indicate that high quality prairies, dominated by native perennial species with low nonnative abundance, should be targeted for recovery sites. We recommend using plant material from Whidbey Island, WA, whose three populations represented in our study consistently performed well. Rare, parasitic plants pose an interesting challenge to restoration practitioners. We examined how the performance of C. levisecta was affected by the availability of different host combinations in the greenhouse and in the field. Castilleja levisecta individuals were grown with two grass individuals (Festuca roemeri; Poaceae), two non-grass hosts (Eriophyllum lanatum; Asteraceae), one individual of each of these species, or without a host. Our greenhouse results provide little support for the complimentary diet hypothesis, which states that parasites grown with multiple host species perform better than individuals grown alone or with a single host. Castilleja levisecta individuals grown with two different species performed better than those co-planted only with F. roemeri, but did not differ from E. lanatum or no-host treatments. In the field, vole activity had indirect effects on C. levisecta survival mediated through host species. Vole tunneling and C. levisecta mortality were strongly associated with host treatments including E. lanatum. Field survival was significantly higher among no-host C. levisecta individuals than those grown with E. lanatum or mixed host treatments. We do not suggest coplanting C. levisecta with E. lanatum in the field. Although no-host C. levisecta individuals had the greatest first year field survival, we suspect that perennial host plants will be beneficial to future survival. Therefore, we recommend planting C. levisecta in the Willamette Valley, OR with F. roemeri. Title: Studies to facilitate reintroduction of golden paintbrush (Castilleja levisecta) to the Willamette Valley, Oregon Author: Lawrence, Beth A. Golden paintbrush (Castilleja levisecta Greenman) historically inhabited the prairies of the Willamette Valley, Oregon. However, this Pacific Northwest endemic is currently restricted to eleven sites in the Puget Trough of Washington and British Columbia. Recovery criteria call for the establishment of new populations throughout the species historic range, including the Willamette Valley. In order to facilitate reintroduction to this region, we examined: (1) habitat characteristics of potential C. levisecta recovery sites in the Willamette Valley and compared them to remaining populations in the Puget Trough, (2) a suite of ecological and genetic factors likely to contribute to reintroduction success using common garden experiments, and (3) how the performance of this rare hemiparasite was affected by the availability of different host combinations in the greenhouse and in the field. Potential C. levisecta reintroduction sites in the Willamette Valley had distinct vegetation communities and soil characteristics compared with remaining populations in the Puget Trough. This disparity was likely related to regional differences in geology, climate, ocean proximity, and land-use history. Many of the species indicative of remaining populations in the Puget Trough were native pereimials, while those of potential reintroduction sites in the Willamette Valley were introduced annuals. Soil characteristics of C. levisecta sites were also distinct among the two ecoregions. Puget Trough sites were located on sandy soils with generally high levels of magnesium and sulfur, while Willamette Valley sites were found on silty-clay soils with high concentrations of potassium and phosphorous. Differences in soil texture, and magnesium and potassium concentrations were associated with plant community divergence among the two regions. Decisions regarding seed source and recovery site selection are especially difficult in portions of a species range that are uninhabited, as no reference populations exist with which to compare ecological information. Using common garden experiments, we tested hypotheses about how C. levisecta transplants would perform in relation to the ecological similarity between seed source and introduction site, the effective population size and genetic diversity of seed sources, and the habitat quality of the recovery site. We observed significant variation in performance measures among source populations and common garden sites. Plant community characteristics, including the abundance of nonnative species and the similarity in community structure between source populations and common garden sites, helped explain the variation in these performance measures. Exotic species cover at common garden sites was associated with a reduction in performance of first year C. levisecta transplants. Survival of second year transplants increased with increasing similarity in plant functional groups between source and common garden sites, supporting the idea of a "home-habitat advantage." These results indicate that high quality prairies, dominated by native perennial species with low nonnative abundance, should be targeted for recovery sites. We recommend using plant material from Whidbey Island, WA, whose three populations represented in our study consistently performed well. Rare, parasitic plants pose an interesting challenge to restoration practitioners. We examined how the performance of C. levisecta was affected by the availability of different host combinations in the greenhouse and in the field. Castilleja levisecta individuals were grown with two grass individuals (Festuca roemeri; Poaceae), two non-grass hosts (Eriophyllum lanatum; Asteraceae), one individual of each of these species, or without a host. Our greenhouse results provide little support for the complimentary diet hypothesis, which states that parasites grown with multiple host species perform better than individuals grown alone or with a single host. Castilleja levisecta individuals grown with two different species performed better than those co-planted only with F. roemeri, but did not differ from E. lanatum or no-host treatments. In the field, vole activity had indirect effects on C. levisecta survival mediated through host species. Vole tunneling and C. levisecta mortality were strongly associated with host treatments including E. lanatum. Field survival was significantly higher among no-host C. levisecta individuals than those grown with E. lanatum or mixed host treatments. We do not suggest coplanting C. levisecta with E. lanatum in the field. Although no-host C. levisecta individuals had the greatest first year field survival, we suspect that perennial host plants will be beneficial to future survival. Therefore, we recommend planting C. levisecta in the Willamette Valley, OR with F. roemeri. Close

• 18. [Article] Ecological survey and interpretation of the Willamette Floodplain Research Natural Area, W.L. Finley National Wildlife Refuge, Oregon

  The purpose of this study was to: (1) evaluate land use and vegetation history of the Willamette Floodplain Research Natural Area; (2) characterize present day vegetation; (3) evaluate the relation of ...

  Citation × Citation Citation Abstract Copy Title: Ecological survey and interpretation of the Willamette Floodplain Research Natural Area, W.L. Finley National Wildlife Refuge, Oregon Author: Streatfeild, Rosemary Welch The purpose of this study was to: (1) evaluate land use and vegetation history of the Willamette Floodplain Research Natural Area; (2) characterize present day vegetation; (3) evaluate the relation of vegetation to environment, and (4) establish a baseline dataset for future trend analysis in order that response of different plant species to fire frequencies may be assessed. I used historical records, aerial photographs, interviews, and literature to ascertain land use and vegetation history. I assumed that the RNA had been maintained as prairie by periodic aboriginal burning. Fire ignited by settlers continued as a management tool into the late 19th century. Grazing was a major disturbance in the late 19th and early 20th centuries, and plowing or some other soil disturbance on the raised elongated mounds may have occurred. With removal of livestock grazing in the early 1960s and only a sporadic burning program, shrub cover increased markedly over the past several decades. I surveyed vegetation in the summer of 1991 in 36 random permanent plots. 1 classified species cover with two-way indicator species analysis, identifying two major communities. One is dominated by tall dense Rosa eg'lanteria, Hypericum perforatum, and many alien weedy species located on slightly elevated mounds, and the other is dominated by shorter but also dense Rosa eglanteria, Deschampsia cespitosa, and many species with wetland affinity on intermounds. Monotypic patches of Spiraea douglasii also occur on intermounds. Species composition strongly correlates with raicrotopography related to an indirect soil moisture index based on wetland status of individual species. Composition correlates less strongly with year since last burn. I confirmed vegetation-environment relations by null hypothesis analysis, tested by multi-response permutation procedure. Vegetation significantly differs on mounds vs. intermounds and vegetation significantly reflects burning history. I ordinated floristic data by non-metric scaling. I also tallied nested frequency data as a baseline for future trend analysis in order to assess change in vegetation in response to fire frequency. Frequency change of Rosa eglanteria will best be detected by change in a 0.01 m2 plot size, Holcus lanatus by a 0.10 m2 plot, and remaining species by a 1.00 m2 plot. Title: Ecological survey and interpretation of the Willamette Floodplain Research Natural Area, W.L. Finley National Wildlife Refuge, Oregon Author: Streatfeild, Rosemary Welch The purpose of this study was to: (1) evaluate land use and vegetation history of the Willamette Floodplain Research Natural Area; (2) characterize present day vegetation; (3) evaluate the relation of vegetation to environment, and (4) establish a baseline dataset for future trend analysis in order that response of different plant species to fire frequencies may be assessed. I used historical records, aerial photographs, interviews, and literature to ascertain land use and vegetation history. I assumed that the RNA had been maintained as prairie by periodic aboriginal burning. Fire ignited by settlers continued as a management tool into the late 19th century. Grazing was a major disturbance in the late 19th and early 20th centuries, and plowing or some other soil disturbance on the raised elongated mounds may have occurred. With removal of livestock grazing in the early 1960s and only a sporadic burning program, shrub cover increased markedly over the past several decades. I surveyed vegetation in the summer of 1991 in 36 random permanent plots. 1 classified species cover with two-way indicator species analysis, identifying two major communities. One is dominated by tall dense Rosa eg'lanteria, Hypericum perforatum, and many alien weedy species located on slightly elevated mounds, and the other is dominated by shorter but also dense Rosa eglanteria, Deschampsia cespitosa, and many species with wetland affinity on intermounds. Monotypic patches of Spiraea douglasii also occur on intermounds. Species composition strongly correlates with raicrotopography related to an indirect soil moisture index based on wetland status of individual species. Composition correlates less strongly with year since last burn. I confirmed vegetation-environment relations by null hypothesis analysis, tested by multi-response permutation procedure. Vegetation significantly differs on mounds vs. intermounds and vegetation significantly reflects burning history. I ordinated floristic data by non-metric scaling. I also tallied nested frequency data as a baseline for future trend analysis in order to assess change in vegetation in response to fire frequency. Frequency change of Rosa eglanteria will best be detected by change in a 0.01 m2 plot size, Holcus lanatus by a 0.10 m2 plot, and remaining species by a 1.00 m2 plot. Close

• 19. [Article] Restructuring of land and community in the remote rural west : the case of Wallowa County, Oregon

  Since at least the 1970s, rural areas in the western United States, as elsewhere across the country and world, have been subject to social, economic, and political forces that have resulted in novel demographic ...

  Citation × Citation Citation Abstract Copy Title: Restructuring of land and community in the remote rural west : the case of Wallowa County, Oregon Author: Abrams, Jesse Since at least the 1970s, rural areas in the western United States, as elsewhere across the country and world, have been subject to social, economic, and political forces that have resulted in novel demographic and land tenure trends when compared to previous decades. Collectively, these processes of restructuring have created material effects in the form of diversifying patterns of land ownership, use, and economic relations and at the same time have precipitated social conflict regarding the legitimacy of various claims on rural space. In this case study, I examine in detail the manifestation of these interrelated material and symbolic dynamics within one particular community, Wallowa County, Oregon, as it experiences a wave of new rural landowners and associated changes in land access and use. I pay particular attention to the categories of "amenity-oriented" and "production-oriented" landowners, as well as year-round and seasonally-resident landowners, because these categories are situated at the center of local discourse regarding land tenure and use dynamics. Methods for this study include key informant interviews with 70 individuals, a mail-administered survey of 209 Wallowa County landowners, review of secondary data sources, and direct observation as a member of the Wallowa County community. This case study includes a land tenure and use history of Wallowa County, a review of pertinent quantitative land ownership and use data, and analyses of the symbolic (discursive), material (land use), and political dimensions of restructuring in Wallowa County. I discuss ways in which observed patterns of land tenure and use reflect complex influences, based ultimately in class, culture, livelihood, and associated identities and environmental ideologies. I pay particular attention to the contradictory nature of narratives of land ownership, rurality, and nonhuman nature and the ways in which these affect land uses and land use politics. I close with a series of recommendations for rural communities experiencing amenity-driven property turnover. Title: Restructuring of land and community in the remote rural west : the case of Wallowa County, Oregon Author: Abrams, Jesse Since at least the 1970s, rural areas in the western United States, as elsewhere across the country and world, have been subject to social, economic, and political forces that have resulted in novel demographic and land tenure trends when compared to previous decades. Collectively, these processes of restructuring have created material effects in the form of diversifying patterns of land ownership, use, and economic relations and at the same time have precipitated social conflict regarding the legitimacy of various claims on rural space. In this case study, I examine in detail the manifestation of these interrelated material and symbolic dynamics within one particular community, Wallowa County, Oregon, as it experiences a wave of new rural landowners and associated changes in land access and use. I pay particular attention to the categories of "amenity-oriented" and "production-oriented" landowners, as well as year-round and seasonally-resident landowners, because these categories are situated at the center of local discourse regarding land tenure and use dynamics. Methods for this study include key informant interviews with 70 individuals, a mail-administered survey of 209 Wallowa County landowners, review of secondary data sources, and direct observation as a member of the Wallowa County community. This case study includes a land tenure and use history of Wallowa County, a review of pertinent quantitative land ownership and use data, and analyses of the symbolic (discursive), material (land use), and political dimensions of restructuring in Wallowa County. I discuss ways in which observed patterns of land tenure and use reflect complex influences, based ultimately in class, culture, livelihood, and associated identities and environmental ideologies. I pay particular attention to the contradictory nature of narratives of land ownership, rurality, and nonhuman nature and the ways in which these affect land uses and land use politics. I close with a series of recommendations for rural communities experiencing amenity-driven property turnover. Close

• 20. [Article] Patterns of tree establishment and vegetation composition in relation to climate and topography of a subalpine meadow landscape, Jefferson Park, Oregon, USA

  The forest alpine tundra ecotone (FTE, also known as alpine treeline or subalpine parkland), is a conspicuous feature of mountain landscapes throughout the world. Climate change-driven increases in temperature ...

  Citation × Citation Citation Abstract Copy Title: Patterns of tree establishment and vegetation composition in relation to climate and topography of a subalpine meadow landscape, Jefferson Park, Oregon, USA Author: Zald, Harold Samuel James The forest alpine tundra ecotone (FTE, also known as alpine treeline or subalpine parkland), is a conspicuous feature of mountain landscapes throughout the world. Climate change-driven increases in temperature are believed to result in FTE movement and tree invasion of subalpine meadows, which have been documented throughout the Northern Hemisphere across a wide range of geographic locations, climatic regimes, forest types, land use histories, and disturbance regimes. Climate-driven FTE movement may have numerous ecological effects such as: positive temperature feedbacks, increased net primary productivity and carbon storage, and declines of plant populations and species. The magnitude of these ecological effects is highly uncertain, but will be largely determined by the rates and spatial extent of FTE movement and meadow invasion. FTE movement and meadow invasion are often considered at global or regional spatial scales in relation to climate, yet they are fundamentally driven by tree regeneration processes that are influenced by a variety of climatic and biophysical factors at micro site, landscape, and regional scales. Much of the research on the FTE has not taken a landscape approach incorporating multi-scale processes. For example, species distribution models used to project climate change effects on future species distributions and plant biodiversity in mountainous landscapes rely on species distribution data that is often sparse and incomplete across FTE landscapes. This dissertation attempts to overcome many of the limitations in FTE research by taking a landscape approach to develop a greater understanding of past spatiotemporal patterns of tree invasion, current spatial patterns of vegetation composition and structure, and potential future patterns of climate-driven tree invasion in the FTE. The setting for this research is Jefferson Park, a 260 ha subalpine parkland landscape in the Oregon High Cascades, USA. This study uses field plots, remotely sensed imagery, airborne Light Detection and Ranging (LiDAR), and simulation modeling to: 1) predictively map current fine-scale species distributions, vegetation structure, and tree ages; 2) reconstruct patterns of tree invasion over the last fifty years in subalpine meadows in relation to climatic conditions, landforms, microtopography, and seed dispersal limitations; and 3) develop a statistical model that projects future patterns of tree invasion into subalpine meadows under different climate scenarios in Jefferson Park. In chapter two, I generated fine-scale spatially-explicit predictions of current vegetation composition, structure, and tree ages in the Jefferson Park study area. Objectives of this chapter were threefold: 1) to characterize spatial patterns of tree ages, vegetation composition, and vegetation structure in a FTE landscape in the Oregon Cascades using predictive mapping; 2) determine how vegetation composition and structure were associated with gradients of environmental factors derived from multispectral satellite imagery and Light Detection and Ranging (LiDAR) data; and 3) determine if predictive mapping characterizations of tree age, vegetation composition, and vegetation structure were improved by the inclusion of LiDAR data. Predictive mapping of vegetation attributes was accomplished using gradient analysis with nearest neighbor imputation; integrating field plots, multispectral SPOT 5 satellite imagery, and LiDAR data. Vegetation composition was best described by SPOT 5 imagery and LiDAR-derived topography, while vegetation structure was best described by LiDAR-derived vegetation heights. Predictions of species occurrence were most accurate for tree species, moderate for shrub species and vegetation groups, and highly variable for graminoid species. Tree age, which was the most accurately predicted vegetation structure variable, indicates the study area was largely un-forested in 1600, gradually invaded by trees from 1600 to the 1920's, and rapidly invaded from the 1920's to 1980. Predictive mapping of vegetation structure variables such as basal area and stand density were subject to large amounts of error, possibly resulting from scale incompatibilities between vegetation patterns and plot size, and/or heterogeneous FTE landscapes where forest structure does not develop along consistent trajectories with stand age. This study suggests integrating multispectral satellite imagery, LiDAR data, and field plots can accurately predict fine-scale spatial characterizations of species distributions and tree invasion in the FTE. This study also indicates that sample design can influence spatial patterns of model uncertainty, which needs to be considered if predictive mapping of vegetation and sensitive ecosystems is a component of inventory and monitoring programs. In chapter three, I focused on quantifying spatiotemporal patterns of subalpine parkland tree invasion in Jefferson Park over the past five decades in relation multi-scale climatic and biophysical controls. LiDAR data provided previously unavailable fine-scale spatial characterizations of microtopography and vegetation structure. I utilized LiDAR, georeferenced field plots, and tree establishment reconstructions to quantify spatiotemporal patterns of tree invasion in relation to late season snow persistence, landform types, fine-scale topographic variability, distances from potential seed sources, and climate variation within 130 ha of the subalpine parkland landscape of Jefferson Park. Tree occurrence (i.e. tree presence in 2 m plots and grid cells) occurred in 7.75% of study area meadows in 1950 and increased to 34.7% in 2007. Landform types and finer-scale patterns of topography and vegetation structure influenced summer snow depth, which influenced temporal and spatial patterns of tree establishment. Tree invasion rates were higher on debris flow landforms, which had lower summer snow depth than glacial landforms, suggesting potentially rapid treeline responses to disturbance events. Tree invasion rates were strongly associated with reduced annual snow fall on glacial landforms, but not on debris flows. Tree establishment was spatially constrained to micro sites with high topographic positions and close proximity to overstory canopy, site conditions associated with low summer snow depth. Seed source limitations placed an additional species-specific spatial constraint on where trees invaded meadows. Climate and topography had an interactive effect, with trees establishing on higher topographic positions during both high snow/low temperature and low snow/high temperature periods, but had greater than expected establishment on lower topographic positions during low snow/high temperature periods. Within the context of larger landform types, topography and proximity to overstory trees constrained where trees established in the meadows, even during climate periods with higher temperatures and lower snowfall. Results of this study suggest large scale climate-driven models of vegetation change may overestimate treeline movement and meadow invasion, because they do not account for biophysical controls limiting tree establishment at multiple spatial scales. In chapter four, I used field data and analyses from chapter 3 to parameterize a spatially and temporally explicit statistical model of fine-scale tree invasion within 130 ha of the Jefferson Park study area. The model incorporated both the climatic and biophysical controls found in chapter 3 to influence tree invasion. The model was used in two ways: (1) to spatially project patterns of tree invasion from 1950 to 2007 in response to historical climate; and (2) to project future tree invasion of the study area from 2007 to 2064 under six different annual snowfall scenarios. Modeling addressed the following questions: (1) Can fine-scale (2 m pixel size) patterns of historical tree invasion be accurately predicted? (2) How sensitive is future tree invasion (and therefore meadow persistence) to different future snowfall scenarios? (3) Are non-climatic factors such as landforms and biotic interactions associated with different spatial patterns of tree invasion? From 1950 to 2007, simulated historical meadow area declined from 82% to 65% of the study area. Model outputs of historical area, spatial distributions, and spatial clustering of tree invasion generally agreed with independent validation, and suggest biotic interactions due to young tree establishment facilitation are important on glacial landforms but not debris flows. Simulations of future scenarios indicated meadow declined to 36 to 43% of the study area by 2064. Projected meadow area declined with reduced annual snow fall, but not under prolonged high and low snow fall periods. Meadows persisted under all future scenarios in 2064. This model suggests subalpine meadows may significantly decline under climate warming, but will still persist in 2064. Micro sites and recruitment limitation may be equally or more important factors than climate change in influencing subalpine landscape change, suggesting local high-elevation persistence of subalpine meadows under future climate warming. Title: Patterns of tree establishment and vegetation composition in relation to climate and topography of a subalpine meadow landscape, Jefferson Park, Oregon, USA Author: Zald, Harold Samuel James The forest alpine tundra ecotone (FTE, also known as alpine treeline or subalpine parkland), is a conspicuous feature of mountain landscapes throughout the world. Climate change-driven increases in temperature are believed to result in FTE movement and tree invasion of subalpine meadows, which have been documented throughout the Northern Hemisphere across a wide range of geographic locations, climatic regimes, forest types, land use histories, and disturbance regimes. Climate-driven FTE movement may have numerous ecological effects such as: positive temperature feedbacks, increased net primary productivity and carbon storage, and declines of plant populations and species. The magnitude of these ecological effects is highly uncertain, but will be largely determined by the rates and spatial extent of FTE movement and meadow invasion. FTE movement and meadow invasion are often considered at global or regional spatial scales in relation to climate, yet they are fundamentally driven by tree regeneration processes that are influenced by a variety of climatic and biophysical factors at micro site, landscape, and regional scales. Much of the research on the FTE has not taken a landscape approach incorporating multi-scale processes. For example, species distribution models used to project climate change effects on future species distributions and plant biodiversity in mountainous landscapes rely on species distribution data that is often sparse and incomplete across FTE landscapes. This dissertation attempts to overcome many of the limitations in FTE research by taking a landscape approach to develop a greater understanding of past spatiotemporal patterns of tree invasion, current spatial patterns of vegetation composition and structure, and potential future patterns of climate-driven tree invasion in the FTE. The setting for this research is Jefferson Park, a 260 ha subalpine parkland landscape in the Oregon High Cascades, USA. This study uses field plots, remotely sensed imagery, airborne Light Detection and Ranging (LiDAR), and simulation modeling to: 1) predictively map current fine-scale species distributions, vegetation structure, and tree ages; 2) reconstruct patterns of tree invasion over the last fifty years in subalpine meadows in relation to climatic conditions, landforms, microtopography, and seed dispersal limitations; and 3) develop a statistical model that projects future patterns of tree invasion into subalpine meadows under different climate scenarios in Jefferson Park. In chapter two, I generated fine-scale spatially-explicit predictions of current vegetation composition, structure, and tree ages in the Jefferson Park study area. Objectives of this chapter were threefold: 1) to characterize spatial patterns of tree ages, vegetation composition, and vegetation structure in a FTE landscape in the Oregon Cascades using predictive mapping; 2) determine how vegetation composition and structure were associated with gradients of environmental factors derived from multispectral satellite imagery and Light Detection and Ranging (LiDAR) data; and 3) determine if predictive mapping characterizations of tree age, vegetation composition, and vegetation structure were improved by the inclusion of LiDAR data. Predictive mapping of vegetation attributes was accomplished using gradient analysis with nearest neighbor imputation; integrating field plots, multispectral SPOT 5 satellite imagery, and LiDAR data. Vegetation composition was best described by SPOT 5 imagery and LiDAR-derived topography, while vegetation structure was best described by LiDAR-derived vegetation heights. Predictions of species occurrence were most accurate for tree species, moderate for shrub species and vegetation groups, and highly variable for graminoid species. Tree age, which was the most accurately predicted vegetation structure variable, indicates the study area was largely un-forested in 1600, gradually invaded by trees from 1600 to the 1920's, and rapidly invaded from the 1920's to 1980. Predictive mapping of vegetation structure variables such as basal area and stand density were subject to large amounts of error, possibly resulting from scale incompatibilities between vegetation patterns and plot size, and/or heterogeneous FTE landscapes where forest structure does not develop along consistent trajectories with stand age. This study suggests integrating multispectral satellite imagery, LiDAR data, and field plots can accurately predict fine-scale spatial characterizations of species distributions and tree invasion in the FTE. This study also indicates that sample design can influence spatial patterns of model uncertainty, which needs to be considered if predictive mapping of vegetation and sensitive ecosystems is a component of inventory and monitoring programs. In chapter three, I focused on quantifying spatiotemporal patterns of subalpine parkland tree invasion in Jefferson Park over the past five decades in relation multi-scale climatic and biophysical controls. LiDAR data provided previously unavailable fine-scale spatial characterizations of microtopography and vegetation structure. I utilized LiDAR, georeferenced field plots, and tree establishment reconstructions to quantify spatiotemporal patterns of tree invasion in relation to late season snow persistence, landform types, fine-scale topographic variability, distances from potential seed sources, and climate variation within 130 ha of the subalpine parkland landscape of Jefferson Park. Tree occurrence (i.e. tree presence in 2 m plots and grid cells) occurred in 7.75% of study area meadows in 1950 and increased to 34.7% in 2007. Landform types and finer-scale patterns of topography and vegetation structure influenced summer snow depth, which influenced temporal and spatial patterns of tree establishment. Tree invasion rates were higher on debris flow landforms, which had lower summer snow depth than glacial landforms, suggesting potentially rapid treeline responses to disturbance events. Tree invasion rates were strongly associated with reduced annual snow fall on glacial landforms, but not on debris flows. Tree establishment was spatially constrained to micro sites with high topographic positions and close proximity to overstory canopy, site conditions associated with low summer snow depth. Seed source limitations placed an additional species-specific spatial constraint on where trees invaded meadows. Climate and topography had an interactive effect, with trees establishing on higher topographic positions during both high snow/low temperature and low snow/high temperature periods, but had greater than expected establishment on lower topographic positions during low snow/high temperature periods. Within the context of larger landform types, topography and proximity to overstory trees constrained where trees established in the meadows, even during climate periods with higher temperatures and lower snowfall. Results of this study suggest large scale climate-driven models of vegetation change may overestimate treeline movement and meadow invasion, because they do not account for biophysical controls limiting tree establishment at multiple spatial scales. In chapter four, I used field data and analyses from chapter 3 to parameterize a spatially and temporally explicit statistical model of fine-scale tree invasion within 130 ha of the Jefferson Park study area. The model incorporated both the climatic and biophysical controls found in chapter 3 to influence tree invasion. The model was used in two ways: (1) to spatially project patterns of tree invasion from 1950 to 2007 in response to historical climate; and (2) to project future tree invasion of the study area from 2007 to 2064 under six different annual snowfall scenarios. Modeling addressed the following questions: (1) Can fine-scale (2 m pixel size) patterns of historical tree invasion be accurately predicted? (2) How sensitive is future tree invasion (and therefore meadow persistence) to different future snowfall scenarios? (3) Are non-climatic factors such as landforms and biotic interactions associated with different spatial patterns of tree invasion? From 1950 to 2007, simulated historical meadow area declined from 82% to 65% of the study area. Model outputs of historical area, spatial distributions, and spatial clustering of tree invasion generally agreed with independent validation, and suggest biotic interactions due to young tree establishment facilitation are important on glacial landforms but not debris flows. Simulations of future scenarios indicated meadow declined to 36 to 43% of the study area by 2064. Projected meadow area declined with reduced annual snow fall, but not under prolonged high and low snow fall periods. Meadows persisted under all future scenarios in 2064. This model suggests subalpine meadows may significantly decline under climate warming, but will still persist in 2064. Micro sites and recruitment limitation may be equally or more important factors than climate change in influencing subalpine landscape change, suggesting local high-elevation persistence of subalpine meadows under future climate warming. Close