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• 161. [Article] Predator Conservation and Trophic Ecology

  Many of Earth’s terrestrial large carnivore species are threatened with extinction. As a result, some of the ecological effects associated with these species may be lost. With the goal of furthering ...

  Citation × Citation Citation Abstract Copy Title: Predator Conservation and Trophic Ecology Author: Wolf, Christopher Year: 2017 Many of Earth’s terrestrial large carnivore species are threatened with extinction. As a result, some of the ecological effects associated with these species may be lost. With the goal of furthering large carnivore conservation research, I conduct three global scale analyses involving these species. First, I explore prey depletion as a threat to large carnivores, finding that loss of prey base is a widespread occurrence and that many prey species are themselves threatened with extinction. Second, I analyze how large carnivore species’ geographic ranges have contracted, linking range contractions to spatial covariates: rural human population density, cropland, and livestock (cattle) density. Finally, I explore options for large carnivore reintroductions, identifying hundreds of potential sites around the world (protected areas and low human footprint regions) where rewilding may have the greatest likelihood of success. In the second part of this dissertation, I transition to considering the basic ecology of predation, with a focus on statistically estimating functional response parameters, which are closely linked to food web interaction strengths. I first show how an observational method for estimating these parameters may be extended using a Bayesian framework that incorporates multiple sources of uncertainty while producing biologically realistic credible intervals. I pay particular attention to the problem of prior selection for modeling multinomial predator feeding survey data, showing that a ‘neutral’ prior is most appropriate. Finally, I consider prior choice in more general nonlinear regression settings, proposing two new prior distributions designed to have low frequentist-sense bias and unifying a set of non-informative priors for a particular function family. I compare these and other non-informative prior distributions using a simulation study and a case study involving whelk feeding behavior in a rocky intertidal ecosystem. Title: Predator Conservation and Trophic Ecology Author: Wolf, Christopher Year: 2017 Many of Earth’s terrestrial large carnivore species are threatened with extinction. As a result, some of the ecological effects associated with these species may be lost. With the goal of furthering large carnivore conservation research, I conduct three global scale analyses involving these species. First, I explore prey depletion as a threat to large carnivores, finding that loss of prey base is a widespread occurrence and that many prey species are themselves threatened with extinction. Second, I analyze how large carnivore species’ geographic ranges have contracted, linking range contractions to spatial covariates: rural human population density, cropland, and livestock (cattle) density. Finally, I explore options for large carnivore reintroductions, identifying hundreds of potential sites around the world (protected areas and low human footprint regions) where rewilding may have the greatest likelihood of success. In the second part of this dissertation, I transition to considering the basic ecology of predation, with a focus on statistically estimating functional response parameters, which are closely linked to food web interaction strengths. I first show how an observational method for estimating these parameters may be extended using a Bayesian framework that incorporates multiple sources of uncertainty while producing biologically realistic credible intervals. I pay particular attention to the problem of prior selection for modeling multinomial predator feeding survey data, showing that a ‘neutral’ prior is most appropriate. Finally, I consider prior choice in more general nonlinear regression settings, proposing two new prior distributions designed to have low frequentist-sense bias and unifying a set of non-informative priors for a particular function family. I compare these and other non-informative prior distributions using a simulation study and a case study involving whelk feeding behavior in a rocky intertidal ecosystem. Close

• 162. [Article] Rainfall seasonality and an ecohydrological feedback offset the potential impact of climate warming on evapotranspiration and groundwater recharge

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291944-7973.

  Citation × Citation Citation Abstract Copy Title: Rainfall seasonality and an ecohydrological feedback offset the potential impact of climate warming on evapotranspiration and groundwater recharge Author: McDonnell, Jeffrey J., Pangle, Luke A., Gregg, Jillian W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291944-7973. Title: Rainfall seasonality and an ecohydrological feedback offset the potential impact of climate warming on evapotranspiration and groundwater recharge Author: McDonnell, Jeffrey J., Pangle, Luke A., Gregg, Jillian W. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291944-7973. Close

• 163. [Article] Atmospheric inverse modeling to constrain regional-scale CO₂ budgets at high spatial and temporal resolution

  We present an inverse modeling framework designed to constrain CO2 budgets at regional scales. The approach captures atmospheric transport processes in high spatiotemporal resolution by coupling a mesoscale ...

  Citation × Citation Citation Abstract Copy Title: Atmospheric inverse modeling to constrain regional-scale CO₂ budgets at high spatial and temporal resolution Author: Law, Beverly E., Vickers, Dean, Michalak, Anna M., Turner, David P., Gockede, Mathias We present an inverse modeling framework designed to constrain CO2 budgets at regional scales. The approach captures atmospheric transport processes in high spatiotemporal resolution by coupling a mesoscale model with Lagrangian Stochastic backward trajectories. Terrestrial biosphere CO₂ emissions are generated through a simple diagnostic flux model that splits the net ecosystem exchange into its major components of gross primary productivity and autotrophic and heterotrophic respirations. The modeling framework assimilates state-of-the-art data sets for advected background CO₂ and anthropogenic fossil fuel emissions as well as highly resolved remote sensing products. We introduce a Bayesian inversion setup, optimizing a posteriori flux base rates for surface types that are defined through remote sensing information. This strategy significantly reduces the number of parameters to be optimized compared with solving fluxes for each individual grid cell, thus permitting description of the surface in a very high resolution. The model is tested using CO₂ concentrations measured in the fall and winter of 2006 at two AmeriFlux sites in Oregon. Because this database does not cover a full seasonal cycle, we focus on conducting model sensitivity tests rather than producing quantitative CO₂ flux estimates. Sensitivity tests on the influence of spatial and temporal resolution indicate that optimum results can be obtained using 4 h time steps and grid sizes of 6 km or less. Further tests demonstrate the importance of dividing biome types by ecoregions to capture their different biogeochemical responses to external forcings across climatic gradients. Detailed stand age information was shown to have a positive effect on model performance. Title: Atmospheric inverse modeling to constrain regional-scale CO₂ budgets at high spatial and temporal resolution Author: Law, Beverly E., Vickers, Dean, Michalak, Anna M., Turner, David P., Gockede, Mathias We present an inverse modeling framework designed to constrain CO2 budgets at regional scales. The approach captures atmospheric transport processes in high spatiotemporal resolution by coupling a mesoscale model with Lagrangian Stochastic backward trajectories. Terrestrial biosphere CO₂ emissions are generated through a simple diagnostic flux model that splits the net ecosystem exchange into its major components of gross primary productivity and autotrophic and heterotrophic respirations. The modeling framework assimilates state-of-the-art data sets for advected background CO₂ and anthropogenic fossil fuel emissions as well as highly resolved remote sensing products. We introduce a Bayesian inversion setup, optimizing a posteriori flux base rates for surface types that are defined through remote sensing information. This strategy significantly reduces the number of parameters to be optimized compared with solving fluxes for each individual grid cell, thus permitting description of the surface in a very high resolution. The model is tested using CO₂ concentrations measured in the fall and winter of 2006 at two AmeriFlux sites in Oregon. Because this database does not cover a full seasonal cycle, we focus on conducting model sensitivity tests rather than producing quantitative CO₂ flux estimates. Sensitivity tests on the influence of spatial and temporal resolution indicate that optimum results can be obtained using 4 h time steps and grid sizes of 6 km or less. Further tests demonstrate the importance of dividing biome types by ecoregions to capture their different biogeochemical responses to external forcings across climatic gradients. Detailed stand age information was shown to have a positive effect on model performance. Close

• 164. [Article] Carbon dynamics following landscape fire: influence of burn severity, climate, and stand history in the Metolius Watershed, Oregon

  Fire is a fundamental disturbance that drives terrestrial and atmospheric carbon dynamics. Previous studies have quantified fire effects on carbon cycling from local to global scales but have focused ...

  Citation × Citation Citation Abstract Copy Title: Carbon dynamics following landscape fire: influence of burn severity, climate, and stand history in the Metolius Watershed, Oregon Author: Meigs, Garrett W. Fire is a fundamental disturbance that drives terrestrial and atmospheric carbon dynamics. Previous studies have quantified fire effects on carbon cycling from local to global scales but have focused nearly exclusively on high-severity, stand-replacement fire. Since 2002, variable-severity wildfires have burned more than 65 000 ha across the east slope of the Oregon Cascades, including 4 large fires that burned ca. 50% of the forested area within the Metolius Watershed in 2002 and 2003. This thesis integrates data from 64 field plots, remote-sensing, and an ecosystem process model to investigate the effects of low-, moderate-, and high-severity fire. The primary research objectives were to: (a) quantify combustion and mortality effects on carbon pools, postfire net ecosystem production (NEP), and potential regeneration trajectories at the stand scale; (b) introduce novel remote-sensing datasets into a modeling framework to assess the importance of low- and moderate-severity fire across the landscape and region. At the stand-scale, the 3 levels of burn severity (overstory tree mortality) resulted in profoundly different impacts on combustion, mortality, postfire carbon balance, and potential regeneration trajectories. Simulated combustion ranged from 16.6 to 32.3 Mg C ha-1, or 13% to 35% of prefire aboveground carbon. C transfers from fire-induced tree mortality were larger in magnitude than combustion, as live aboveground C decreased by >90% from low- to high-severity stands. Despite this decline, total net primary productivity (NPP) was only 40% lower in high- vs. low-severity stands, reflecting a compensatory effect of non-tree NPP. Dead wood respiratory losses were small relative to C uptake (range: 10-35% of total NPP), suggesting important decomposition lags in this seasonally-arid system. Although soil C, soil respiration, and fine root NPP were conserved across severity classes, NEP declined with increasing severity, driven by trends in aboveground NPP. Postfire conifer seedling density was generally abundant and varied over 5 orders of magnitude (study-wide median: 812, range: 0 – 62 134 seedlings ha-1). Seedling density was negatively correlated with overstory mortality, whereas shrub biomass showed the opposite response, indicating a wide range of potential successional trajectories. Despite substantial combustion and mortality effects on carbon pools and fluxes, the rapid response of postfire vegetation, coupled with conservation of belowground processes, may offset long-term declines in carbon storage, indicating a surprising degree of postfire stability. These stand-scale results describe a broad range of fire effects—a high degree of pyrodiversity—but because burn severity was not evenly distributed across space, the landscape-level fire effects depend on the severity mosaic. At the landscape-scale, moderate- and low-severity fire contributed 25% and 11% of total estimated pyrogenic carbon emission, respectively (0.66 Tg C total, or ca. 2.2% of statewide anthropogenic CO2 emissions equivalent from the same 2-year period). Moderate- and low-severity fire accounted for 23% and 5% of landscape-level tree mortality, respectively, which resulted in the transfer of 2.00 Tg C from live to dead pools. This carbon transfer was ca. 3-fold higher than the one-time pulse from pyrogenic emission, but it will likely take decades for this dead wood to decompose via heterotrophic respiration. The inclusion of moderate-severity fire reduced postfire (2004) mean annual NEP by 39% compared to the high-severity only scenario; low-severity fire influence on NEP was small (additional reduction of 11% in mean NEP), likely because of high tree survivorship and the relatively lower areal coverage of low-severity fire. One year postfire, burned areas were a strong C source (net C exchange across 53 000 ha: -0.065 Tg C y-1; mean ± SD: -123 ± 110 g C m-2 y-1) vs. a prefire mean near C neutral (1997-2001 mean NEP ± SD: -5 ± 51 g C m-2 y-1). The model has been known to underestimate carbon uptake in mature and old semi-arid forests, so the prefire value is likely underestimated. Despite the resurgence of wildfire across western North America, including a substantial increase in the proportion of high-severity fire in the ecoregions studied here, low- and moderate-severity wildfire accounts for the majority of burned area in the Pacific Northwest region. This non-stand-replacement fire has important consequences for carbon loss and uptake at landscape- and regional-scales. The results from this thesis suggest that by accounting for the full gradient of fire effects, carbon modelers can substantially reduce uncertainties in key components of regional and global carbon budgets, particularly pyrogenic emissions, mortality, and NEP. Understanding the effects of disturbance variability on terrestrial carbon cycling will become increasingly important in the context of emerging regional and global carbon policies. Title: Carbon dynamics following landscape fire: influence of burn severity, climate, and stand history in the Metolius Watershed, Oregon Author: Meigs, Garrett W. Fire is a fundamental disturbance that drives terrestrial and atmospheric carbon dynamics. Previous studies have quantified fire effects on carbon cycling from local to global scales but have focused nearly exclusively on high-severity, stand-replacement fire. Since 2002, variable-severity wildfires have burned more than 65 000 ha across the east slope of the Oregon Cascades, including 4 large fires that burned ca. 50% of the forested area within the Metolius Watershed in 2002 and 2003. This thesis integrates data from 64 field plots, remote-sensing, and an ecosystem process model to investigate the effects of low-, moderate-, and high-severity fire. The primary research objectives were to: (a) quantify combustion and mortality effects on carbon pools, postfire net ecosystem production (NEP), and potential regeneration trajectories at the stand scale; (b) introduce novel remote-sensing datasets into a modeling framework to assess the importance of low- and moderate-severity fire across the landscape and region. At the stand-scale, the 3 levels of burn severity (overstory tree mortality) resulted in profoundly different impacts on combustion, mortality, postfire carbon balance, and potential regeneration trajectories. Simulated combustion ranged from 16.6 to 32.3 Mg C ha-1, or 13% to 35% of prefire aboveground carbon. C transfers from fire-induced tree mortality were larger in magnitude than combustion, as live aboveground C decreased by >90% from low- to high-severity stands. Despite this decline, total net primary productivity (NPP) was only 40% lower in high- vs. low-severity stands, reflecting a compensatory effect of non-tree NPP. Dead wood respiratory losses were small relative to C uptake (range: 10-35% of total NPP), suggesting important decomposition lags in this seasonally-arid system. Although soil C, soil respiration, and fine root NPP were conserved across severity classes, NEP declined with increasing severity, driven by trends in aboveground NPP. Postfire conifer seedling density was generally abundant and varied over 5 orders of magnitude (study-wide median: 812, range: 0 – 62 134 seedlings ha-1). Seedling density was negatively correlated with overstory mortality, whereas shrub biomass showed the opposite response, indicating a wide range of potential successional trajectories. Despite substantial combustion and mortality effects on carbon pools and fluxes, the rapid response of postfire vegetation, coupled with conservation of belowground processes, may offset long-term declines in carbon storage, indicating a surprising degree of postfire stability. These stand-scale results describe a broad range of fire effects—a high degree of pyrodiversity—but because burn severity was not evenly distributed across space, the landscape-level fire effects depend on the severity mosaic. At the landscape-scale, moderate- and low-severity fire contributed 25% and 11% of total estimated pyrogenic carbon emission, respectively (0.66 Tg C total, or ca. 2.2% of statewide anthropogenic CO2 emissions equivalent from the same 2-year period). Moderate- and low-severity fire accounted for 23% and 5% of landscape-level tree mortality, respectively, which resulted in the transfer of 2.00 Tg C from live to dead pools. This carbon transfer was ca. 3-fold higher than the one-time pulse from pyrogenic emission, but it will likely take decades for this dead wood to decompose via heterotrophic respiration. The inclusion of moderate-severity fire reduced postfire (2004) mean annual NEP by 39% compared to the high-severity only scenario; low-severity fire influence on NEP was small (additional reduction of 11% in mean NEP), likely because of high tree survivorship and the relatively lower areal coverage of low-severity fire. One year postfire, burned areas were a strong C source (net C exchange across 53 000 ha: -0.065 Tg C y-1; mean ± SD: -123 ± 110 g C m-2 y-1) vs. a prefire mean near C neutral (1997-2001 mean NEP ± SD: -5 ± 51 g C m-2 y-1). The model has been known to underestimate carbon uptake in mature and old semi-arid forests, so the prefire value is likely underestimated. Despite the resurgence of wildfire across western North America, including a substantial increase in the proportion of high-severity fire in the ecoregions studied here, low- and moderate-severity wildfire accounts for the majority of burned area in the Pacific Northwest region. This non-stand-replacement fire has important consequences for carbon loss and uptake at landscape- and regional-scales. The results from this thesis suggest that by accounting for the full gradient of fire effects, carbon modelers can substantially reduce uncertainties in key components of regional and global carbon budgets, particularly pyrogenic emissions, mortality, and NEP. Understanding the effects of disturbance variability on terrestrial carbon cycling will become increasingly important in the context of emerging regional and global carbon policies. Close

• 165. [Article] Isotopic composition of respired CO2 in a small watershed : development and testing of an automated sampling system and analysis of first year data

  Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming ...

  Citation × Citation Citation Abstract Copy Title: Isotopic composition of respired CO2 in a small watershed : development and testing of an automated sampling system and analysis of first year data Author: Hauck, Mark J. Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming are hampered by uncertainty in the ability of the earth’s ecosystems to counteract this effect by sequestering carbon dioxide by increases in the mass of vegetation, soil storage, or storage in the Earth’s oceans. Measurement of the carbon isotopic composition of respired CO2 (Delta [superscript 13]C[subscript R-eco]) is becoming increasingly important to ecosystem studies because the information contained in this respiration can be an indicator of ecosystem stress and productivity. This study was conducted as part of a larger research project aimed at developing and testing the capacity for measuring Delta [superscript 13]C[subscript R-eco] in a small, steeply-sloped watershed in western Oregon. The goals of this study were: (1) to develop and test an automated system for sampling nocturnal air to be analyzed in a laboratory for isotopic composition; (2) to collect samples of the atmosphere from the nocturnal cold air drainage of a steeply sloped watershed in the HJ Andrews Experimental Forest and bring those samples back to a laboratory to be analyzed for CO2 concentration and carbon isotope composition; and (3) to conduct an initial analysis of the relationship between Delta [superscript 13]C[subscript R-eco] for the first year of deployment and two environmental forcing factors, soil moisture and atmospheric vapor pressure deficit (VPD). The automated system was designed during 2004 and 2005, tested in the laboratory during the month of April 2005, debugged in the field between August 2004 and May 2005, and deployed during the period from late May, 2005 to November 2005. The design objectives for the automated sampling system were: (1) light weight; (2) portability; (3) high reliability; (4) fast dynamic response; (5) unattended operation; and (6) the ability to capture, transport, and store samples over several days with no loss of data integrity. The automated sampling system proved capable of collecting 15 samples per sampling period and utilized a 16 loop stainless steel sample capture valve (Valcon Instruments, 7806 Bobbitt Houston, TX 77055) for sample containment. The system was designed for automated, labor free operation and uses a Campbell CR 10X datalogger (Campbell Scientific, Inc, 815 West 1800 North, Logan Utah) for both data acquisition and system control. This unique architecture was selected to enhance the ability of the system to capture samples which could be analyzed simultaneously for both CO2 concentration and Delta[superscript 13]C. The system was deployed in a steeply sloped watershed and proved to have a combination of light weight (approximately 34 kg total weight) and portability which allowed a wide range of field personnel to deploy the system without undue physical stress. Some initial issues with electrical wiring, plumbing connections, and control program bugs hampered early season performance, but once the system was debugged, it functioned reliably throughout the remainder of the field season with a minimum of operator input. Test results showed that the automated sampler had a maximum sampling frequency of 0.043 hertz, could store air samples for up to 3 days without detectable changes in either isotopic composition or CO2 concentration and displayed greater precision than the hand sampling process it replaced. Using the automated sampling system, sets of nocturnal cold air drainage samples were collected on nine evenings in 2005. The 15 samples acquired for each of these nine evenings were used to generate Keeling plots to determine a single value of the isotopic composition of ecosystem respiration (Delta [superscript 13]C[subscript R-eco]) for each sampling date. The range of Delta [superscript 13]C[subscript R-eco] over the season was 3.9 0/00 and the values of Delta [superscript 13]C[subscript R-eco] varied from -26.2 0/00 on July 13, 2005 to -22.9 0/00 on September 14, 2005. This seasonal pattern of Delta [superscript 13]C[subscript R-eco] was consistent with a forest under drought stress. Trends in ecosystem respiration over the growing season were compared to corresponding measurements of the environmental variables of soil moisture content and VPD. VPD ranged from 2.7 to 1758 Pa, but these patterns of VPD were not significantly correlated to seasonal Delta [superscript 13]C[subscript R-eco] patterns over the study period. Soil moisture content ranged between 7.2% and 44.3% over the study period and soil moisture content temporal patterns were highly correlated with rain events exceeding 4 mm. The soil moisture content pattern for the south-facing slope was significantly correlated with the seasonal Delta [superscript 13]C[subscript R-eco] pattern, although other groupings of soil moisture content were not. The automated system designed for this project met all of its design objectives and functioned adequately throughout the sampling period. The carbon isotope patterns were consistent with a forest under drought stress and the soil moisture content of the plots on the south-facing slopes of the watershed were significantly correlated to these isotope patterns. The future of this system could be enhanced by making adjustments to the supporting hardware, control program and operating procedure to enable larger quantities of samples, more rapid sampling rates, and automated hardware diagnostics. Title: Isotopic composition of respired CO2 in a small watershed : development and testing of an automated sampling system and analysis of first year data Author: Hauck, Mark J. Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming are hampered by uncertainty in the ability of the earth’s ecosystems to counteract this effect by sequestering carbon dioxide by increases in the mass of vegetation, soil storage, or storage in the Earth’s oceans. Measurement of the carbon isotopic composition of respired CO2 (Delta [superscript 13]C[subscript R-eco]) is becoming increasingly important to ecosystem studies because the information contained in this respiration can be an indicator of ecosystem stress and productivity. This study was conducted as part of a larger research project aimed at developing and testing the capacity for measuring Delta [superscript 13]C[subscript R-eco] in a small, steeply-sloped watershed in western Oregon. The goals of this study were: (1) to develop and test an automated system for sampling nocturnal air to be analyzed in a laboratory for isotopic composition; (2) to collect samples of the atmosphere from the nocturnal cold air drainage of a steeply sloped watershed in the HJ Andrews Experimental Forest and bring those samples back to a laboratory to be analyzed for CO2 concentration and carbon isotope composition; and (3) to conduct an initial analysis of the relationship between Delta [superscript 13]C[subscript R-eco] for the first year of deployment and two environmental forcing factors, soil moisture and atmospheric vapor pressure deficit (VPD). The automated system was designed during 2004 and 2005, tested in the laboratory during the month of April 2005, debugged in the field between August 2004 and May 2005, and deployed during the period from late May, 2005 to November 2005. The design objectives for the automated sampling system were: (1) light weight; (2) portability; (3) high reliability; (4) fast dynamic response; (5) unattended operation; and (6) the ability to capture, transport, and store samples over several days with no loss of data integrity. The automated sampling system proved capable of collecting 15 samples per sampling period and utilized a 16 loop stainless steel sample capture valve (Valcon Instruments, 7806 Bobbitt Houston, TX 77055) for sample containment. The system was designed for automated, labor free operation and uses a Campbell CR 10X datalogger (Campbell Scientific, Inc, 815 West 1800 North, Logan Utah) for both data acquisition and system control. This unique architecture was selected to enhance the ability of the system to capture samples which could be analyzed simultaneously for both CO2 concentration and Delta[superscript 13]C. The system was deployed in a steeply sloped watershed and proved to have a combination of light weight (approximately 34 kg total weight) and portability which allowed a wide range of field personnel to deploy the system without undue physical stress. Some initial issues with electrical wiring, plumbing connections, and control program bugs hampered early season performance, but once the system was debugged, it functioned reliably throughout the remainder of the field season with a minimum of operator input. Test results showed that the automated sampler had a maximum sampling frequency of 0.043 hertz, could store air samples for up to 3 days without detectable changes in either isotopic composition or CO2 concentration and displayed greater precision than the hand sampling process it replaced. Using the automated sampling system, sets of nocturnal cold air drainage samples were collected on nine evenings in 2005. The 15 samples acquired for each of these nine evenings were used to generate Keeling plots to determine a single value of the isotopic composition of ecosystem respiration (Delta [superscript 13]C[subscript R-eco]) for each sampling date. The range of Delta [superscript 13]C[subscript R-eco] over the season was 3.9 0/00 and the values of Delta [superscript 13]C[subscript R-eco] varied from -26.2 0/00 on July 13, 2005 to -22.9 0/00 on September 14, 2005. This seasonal pattern of Delta [superscript 13]C[subscript R-eco] was consistent with a forest under drought stress. Trends in ecosystem respiration over the growing season were compared to corresponding measurements of the environmental variables of soil moisture content and VPD. VPD ranged from 2.7 to 1758 Pa, but these patterns of VPD were not significantly correlated to seasonal Delta [superscript 13]C[subscript R-eco] patterns over the study period. Soil moisture content ranged between 7.2% and 44.3% over the study period and soil moisture content temporal patterns were highly correlated with rain events exceeding 4 mm. The soil moisture content pattern for the south-facing slope was significantly correlated with the seasonal Delta [superscript 13]C[subscript R-eco] pattern, although other groupings of soil moisture content were not. The automated system designed for this project met all of its design objectives and functioned adequately throughout the sampling period. The carbon isotope patterns were consistent with a forest under drought stress and the soil moisture content of the plots on the south-facing slopes of the watershed were significantly correlated to these isotope patterns. The future of this system could be enhanced by making adjustments to the supporting hardware, control program and operating procedure to enable larger quantities of samples, more rapid sampling rates, and automated hardware diagnostics. Close

• 166. [Article] Integration of MODIS land and atmosphere products with a coupled-process model to estimate gross primary productivity and evapotranspiration from 1 km to global scales

  This is the publisher’s final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://sites.agu.org/.

  Citation × Citation Citation Abstract Copy Title: Integration of MODIS land and atmosphere products with a coupled-process model to estimate gross primary productivity and evapotranspiration from 1 km to global scales Author: van Gorsel, Eva, Baldocchi, Dennis D., Ryu, Youngryel, Knohl, Alexander, Li, Jie, Kobayashi, Hideki, Roupsard, Olivier, Beringer, Jason, Law, Beverly E., Black, T. Andy, van Ingen, Catharine This is the publisher’s final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://sites.agu.org/. Title: Integration of MODIS land and atmosphere products with a coupled-process model to estimate gross primary productivity and evapotranspiration from 1 km to global scales Author: van Gorsel, Eva, Baldocchi, Dennis D., Ryu, Youngryel, Knohl, Alexander, Li, Jie, Kobayashi, Hideki, Roupsard, Olivier, Beringer, Jason, Law, Beverly E., Black, T. Andy, van Ingen, Catharine This is the publisher’s final pdf. The published article is copyrighted by American Geophysical Union and can be found at: http://sites.agu.org/. Close

• 167. [Article] Evaluation and improvement of the Community Land Model (CLM4) in Oregon forests

  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 Copernicus ...

  Citation × Citation Citation Abstract Copy Title: Evaluation and improvement of the Community Land Model (CLM4) in Oregon forests Author: Thornton, P. E., Law, B. E., Hudiburg, T.W. 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 Copernicus Publications and can be found at: http://publications.copernicus.org/ on behalf of the European Geosciences Union (http://www.egu.eu/publications/). Title: Evaluation and improvement of the Community Land Model (CLM4) in Oregon forests Author: Thornton, P. E., Law, B. E., Hudiburg, T.W. 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 Copernicus Publications and can be found at: http://publications.copernicus.org/ on behalf of the European Geosciences Union (http://www.egu.eu/publications/). Close

• 168. [Article] Realized and potential climate responses of lichen and bryophyte communities in a national forest inventory

  Climate and terrestrial vegetation have had mutual feedbacks for nearly five hundred million years, yet both are now departing from recent historical norms, with uncertain implications for forest ecosystems. ...

  Citation × Citation Citation Abstract Copy Title: Realized and potential climate responses of lichen and bryophyte communities in a national forest inventory Author: Smith, Robert J. Climate and terrestrial vegetation have had mutual feedbacks for nearly five hundred million years, yet both are now departing from recent historical norms, with uncertain implications for forest ecosystems. This dissertation outlines the current and potential future climate responses of lichen and bryophyte communities in the United States as part of a national forest inventory. The first task was to identify influences on carbon and nitrogen storage of moss and lichen “ground layers” in subarctic interior Alaska. Nutrient stores were more sensitive to local vegetation and topography than regional macroclimate. Nutrients and biomass were greatest among apparently less disturbed stands. This suggests that climatic changes could diminish ground layer nutrient storage indirectly if they promote intensifying wildfire regimes or expansions of competitive vascular vegetation. Turning to focus on species diversity, the next task was to quantify the strength of relationship between epiphytic lichen community composition and macroclimate across the 4,000 km-long swath of the U.S. Pacific coastal states. The strongest fitting lichen response gradients involved precipitation, temperature, and a heat-moisture index. Lichen indicator species (diagnostic of ten defined climate zones) emerged as useful monitoring tools because their abundance changes could signal shifting climate zone boundaries. After establishing key present-day climatic relationships, the next task was to pinpoint nationwide locations where epiphytic lichen communities will be most vulnerable to species losses under current and future warming scenarios. Novel niche-based metrics revealed greatest vulnerability among supposedly “warm-adapted” communities in southern/lowland locations, contrary to usual assumptions centering on cooler northern/montane habitats. Vulnerability analyses can steer conservation and monitoring attention to specific locations where warming is most expected to affect ecological communities. The final task, to anticipate how warming will impact individual lichen performance, was addressed by quantifying how experimental climate treatments (whole-ecosystem warming and CO2 additions) affected growth of the boreal epiphytic lichen species Evernia mesomorpha. Over just one year, incremental warming and concurrent drying caused progressive growth declines and biomass losses among individual transplants. Such warming-induced biomass losses of epiphytic lichens could precede local population extinctions and regional range contractions. Overall, this dissertation weaves together multiple lines of evidence from nutrient, diversity and growth responses to indicate the ecological effects of climate and climatic changes on vegetation in a national forest inventory context. This work suggests a pathway for integrating lichen and bryophyte responses into nationwide climate monitoring to address emergent interactions between humans, vegetation, and the global climate commons. Title: Realized and potential climate responses of lichen and bryophyte communities in a national forest inventory Author: Smith, Robert J. Climate and terrestrial vegetation have had mutual feedbacks for nearly five hundred million years, yet both are now departing from recent historical norms, with uncertain implications for forest ecosystems. This dissertation outlines the current and potential future climate responses of lichen and bryophyte communities in the United States as part of a national forest inventory. The first task was to identify influences on carbon and nitrogen storage of moss and lichen “ground layers” in subarctic interior Alaska. Nutrient stores were more sensitive to local vegetation and topography than regional macroclimate. Nutrients and biomass were greatest among apparently less disturbed stands. This suggests that climatic changes could diminish ground layer nutrient storage indirectly if they promote intensifying wildfire regimes or expansions of competitive vascular vegetation. Turning to focus on species diversity, the next task was to quantify the strength of relationship between epiphytic lichen community composition and macroclimate across the 4,000 km-long swath of the U.S. Pacific coastal states. The strongest fitting lichen response gradients involved precipitation, temperature, and a heat-moisture index. Lichen indicator species (diagnostic of ten defined climate zones) emerged as useful monitoring tools because their abundance changes could signal shifting climate zone boundaries. After establishing key present-day climatic relationships, the next task was to pinpoint nationwide locations where epiphytic lichen communities will be most vulnerable to species losses under current and future warming scenarios. Novel niche-based metrics revealed greatest vulnerability among supposedly “warm-adapted” communities in southern/lowland locations, contrary to usual assumptions centering on cooler northern/montane habitats. Vulnerability analyses can steer conservation and monitoring attention to specific locations where warming is most expected to affect ecological communities. The final task, to anticipate how warming will impact individual lichen performance, was addressed by quantifying how experimental climate treatments (whole-ecosystem warming and CO2 additions) affected growth of the boreal epiphytic lichen species Evernia mesomorpha. Over just one year, incremental warming and concurrent drying caused progressive growth declines and biomass losses among individual transplants. Such warming-induced biomass losses of epiphytic lichens could precede local population extinctions and regional range contractions. Overall, this dissertation weaves together multiple lines of evidence from nutrient, diversity and growth responses to indicate the ecological effects of climate and climatic changes on vegetation in a national forest inventory context. This work suggests a pathway for integrating lichen and bryophyte responses into nationwide climate monitoring to address emergent interactions between humans, vegetation, and the global climate commons. Close

• 169. [Article] The Response and Effect of Emergent Coastal Vegetation to Sedimentation and the Distribution of Coastal Vegetation Communities along Environmental Gradients

  Coastal marsh vegetation is an important component in maintaining marsh stability that is threatened by changes in sedimentation, sea level rise, natural and anthropogenic disturbances, and competition ...

  Citation × Citation Citation Abstract Copy Title: The Response and Effect of Emergent Coastal Vegetation to Sedimentation and the Distribution of Coastal Vegetation Communities along Environmental Gradients Author: Lemein, Todd Coastal marsh vegetation is an important component in maintaining marsh stability that is threatened by changes in sedimentation, sea level rise, natural and anthropogenic disturbances, and competition from invasive species. Vegetation has been demonstrated to reduce wave energy, increase sedimentation, and decrease erosion in tidal environments under a range of conditions. Similarities and differences between the morphology of vegetation species may play an important role in understanding the mechanism between vegetation, sedimentation, and wave energy. Diversity of species within vegetation communities has been shown to reduce the success of biological invasions from invasive species as well as increase the ability of the community to adapt to environmental changes such as inundation period (period of time vegetation is submerged partially or fully by water). The species present along coastal marshes and specifically at the interface between vegetated marsh and unvegetated mudflat provide an opportunity to better understand the interactions between vegetation and its physical setting. In this dissertation I focus on the species and vegetation communities that are present at this interface of the terrestrial and aquatic boundary to better understand how plant communities may be characterized, how they respond to disturbance, how they are distributed, and how they may influence the physical environment in which they grow. In Chapter two, I explore the ability to use image analysis and the lateral obstruction of vegetation to describe a species density, height and diameter and evaluate the tradeoffs in using image analysis over more traditional methods. In Chapter three, I evaluate the response of an emergent vegetation species, threesquare bulrush (Schoenoplectus pungens), to different depths of complete burial as could be expected from extreme storms, hurricanes, tsunamis, or restoration efforts involving sediment amendment. Chapter four describes the distribution of coastal marsh communities of the Laurentian Great Lakes along an elevational gradient beginning at the terrestrial and aquatic boundary, identifying patterns of wetland distribution, species composition, and exotic plant invasion. In Chapter five, I conclude the dissertation with an evaluation of the effects of two morphologically distinct species of emergent marsh vegetation, threesquare bulrush and Lyngbye’s sedge (Carex lyngbyei), on the sedimentation rate and variability in Tillamook Bay, OR and compare the results to the current understanding of vegetation-sediment feedback. In Chapter two, I found that for morphologically simple species, such as S. pungens, image analysis of lateral obstruction can be used to determine important morphological characteristics of a stand of vegetation including the mean stem height, density, and mean diameter. The method provides a description of the vertical variation in morphologic structure, providing a rapid analytic tool for exploring the effects of vegetation on wave and sediment interaction. However, I note that more morphologically complex species, such as sedges and grasses may not be as easily described using image analysis. In Chapter three, I determined that aboveground biomass of S. pungens would return to pre-disturbance levels following burial by up to 40 cm of mineral sediment after two years. Vegetation was observed to survive burials depths of up to 80 cm, although initially at much lower density. The aboveground height of stems were statistically similar to unburied controls after two years, which is important for the continuation of ecosystem services such as wave attenuation. The results suggest that S. pungens is capable of returning to pre-disturbance levels of biomass following large natural sedimentation events such as extreme storms, hurricanes, or tsunamis, and that burying portions of marshes with sediment as a restoration tool is not likely to harm the buried vegetation. In Chapter four I refine and describe 21 coastal vegetation communities in the Laurentian Great Lakes and the ecological gradients along which they are distributed. Latitude, agricultural intensity, site geomorphology, substrate, and water depth were found to be the significant variables that determined community distribution. Additionally, we observed an expansion of invasive plant species near areas of high anthropogenic activity such as farms and urban centers. In Chapter five, I found that there were species-specific differences in sedimentation rate and variability in Tillamook Bay, OR. Schoenoplectus pungens was found to retain more sediment than C. lyngbyei. Sedimentation rate was observed to be variable by location within the estuary. Two patterns of sediment accumulation were observed. The first occurred along vegetation gradients, with increased sedimentation farther into vegetation beds. In the second pattern, sediment accumulation was observed to be greatest at the marsh/mudflat boundary where vegetation was dense and then decreased with increasing depth into the vegetation. In conclusion, this dissertation explores the interaction of emergent wetland vegetation with environmental factors. Image analysis provides a new tool for rapid characterization of vegetation structure, a burial experiment documents Schoenoplectus pungens’ tolerance to sand burial, a field study at Tillamook, OR documents the relationship between sediment accumulation and emergent vegetation beds, and a wetland classification is developed for coastal wetlands along the Great Lakes, which includes plant communities dominated by S. pungens. Title: The Response and Effect of Emergent Coastal Vegetation to Sedimentation and the Distribution of Coastal Vegetation Communities along Environmental Gradients Author: Lemein, Todd Coastal marsh vegetation is an important component in maintaining marsh stability that is threatened by changes in sedimentation, sea level rise, natural and anthropogenic disturbances, and competition from invasive species. Vegetation has been demonstrated to reduce wave energy, increase sedimentation, and decrease erosion in tidal environments under a range of conditions. Similarities and differences between the morphology of vegetation species may play an important role in understanding the mechanism between vegetation, sedimentation, and wave energy. Diversity of species within vegetation communities has been shown to reduce the success of biological invasions from invasive species as well as increase the ability of the community to adapt to environmental changes such as inundation period (period of time vegetation is submerged partially or fully by water). The species present along coastal marshes and specifically at the interface between vegetated marsh and unvegetated mudflat provide an opportunity to better understand the interactions between vegetation and its physical setting. In this dissertation I focus on the species and vegetation communities that are present at this interface of the terrestrial and aquatic boundary to better understand how plant communities may be characterized, how they respond to disturbance, how they are distributed, and how they may influence the physical environment in which they grow. In Chapter two, I explore the ability to use image analysis and the lateral obstruction of vegetation to describe a species density, height and diameter and evaluate the tradeoffs in using image analysis over more traditional methods. In Chapter three, I evaluate the response of an emergent vegetation species, threesquare bulrush (Schoenoplectus pungens), to different depths of complete burial as could be expected from extreme storms, hurricanes, tsunamis, or restoration efforts involving sediment amendment. Chapter four describes the distribution of coastal marsh communities of the Laurentian Great Lakes along an elevational gradient beginning at the terrestrial and aquatic boundary, identifying patterns of wetland distribution, species composition, and exotic plant invasion. In Chapter five, I conclude the dissertation with an evaluation of the effects of two morphologically distinct species of emergent marsh vegetation, threesquare bulrush and Lyngbye’s sedge (Carex lyngbyei), on the sedimentation rate and variability in Tillamook Bay, OR and compare the results to the current understanding of vegetation-sediment feedback. In Chapter two, I found that for morphologically simple species, such as S. pungens, image analysis of lateral obstruction can be used to determine important morphological characteristics of a stand of vegetation including the mean stem height, density, and mean diameter. The method provides a description of the vertical variation in morphologic structure, providing a rapid analytic tool for exploring the effects of vegetation on wave and sediment interaction. However, I note that more morphologically complex species, such as sedges and grasses may not be as easily described using image analysis. In Chapter three, I determined that aboveground biomass of S. pungens would return to pre-disturbance levels following burial by up to 40 cm of mineral sediment after two years. Vegetation was observed to survive burials depths of up to 80 cm, although initially at much lower density. The aboveground height of stems were statistically similar to unburied controls after two years, which is important for the continuation of ecosystem services such as wave attenuation. The results suggest that S. pungens is capable of returning to pre-disturbance levels of biomass following large natural sedimentation events such as extreme storms, hurricanes, or tsunamis, and that burying portions of marshes with sediment as a restoration tool is not likely to harm the buried vegetation. In Chapter four I refine and describe 21 coastal vegetation communities in the Laurentian Great Lakes and the ecological gradients along which they are distributed. Latitude, agricultural intensity, site geomorphology, substrate, and water depth were found to be the significant variables that determined community distribution. Additionally, we observed an expansion of invasive plant species near areas of high anthropogenic activity such as farms and urban centers. In Chapter five, I found that there were species-specific differences in sedimentation rate and variability in Tillamook Bay, OR. Schoenoplectus pungens was found to retain more sediment than C. lyngbyei. Sedimentation rate was observed to be variable by location within the estuary. Two patterns of sediment accumulation were observed. The first occurred along vegetation gradients, with increased sedimentation farther into vegetation beds. In the second pattern, sediment accumulation was observed to be greatest at the marsh/mudflat boundary where vegetation was dense and then decreased with increasing depth into the vegetation. In conclusion, this dissertation explores the interaction of emergent wetland vegetation with environmental factors. Image analysis provides a new tool for rapid characterization of vegetation structure, a burial experiment documents Schoenoplectus pungens’ tolerance to sand burial, a field study at Tillamook, OR documents the relationship between sediment accumulation and emergent vegetation beds, and a wetland classification is developed for coastal wetlands along the Great Lakes, which includes plant communities dominated by S. pungens. Close

• 170. [Image] Gerber-Willow Valley Watershed Analysis

  	x, 386 p., ill., maps (some col.); Cover title; "July 2003"
  	Citation × Citation Citation Abstract Copy Title: Gerber-Willow Valley Watershed Analysis Author: U.S. Department of the Interior. Bureau of Land Management; Klamath Falls Resource Area Office; U.S. Department of Agriculture. Forest Service; Fremont-Winema National Forests; Modoc National Forest Year: 2003, 2006, 2005 x, 386 p., ill., maps (some col.); Cover title; "July 2003" Title: Gerber-Willow Valley Watershed Analysis Author: U.S. Department of the Interior. Bureau of Land Management; Klamath Falls Resource Area Office; U.S. Department of Agriculture. Forest Service; Fremont-Winema National Forests; Modoc National Forest Year: 2003, 2006, 2005 x, 386 p., ill., maps (some col.); Cover title; "July 2003" Close