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• 1. [Article] Gas Transfer Velocities in Small Forested Ponds

  Inland waters actively exchange gases with the atmosphere, and the gas exchange rate informs system biogeochemistry, ecology, and global carbon budgets. Gas exchange in medium- to large-sized lakes is ...

  Citation × Citation Citation Abstract Copy Title: Gas Transfer Velocities in Small Forested Ponds Author: Holgerson, Meredith A., Farr, Emily R., Raymond, Peter A. Year: 2017 Inland waters actively exchange gases with the atmosphere, and the gas exchange rate informs system biogeochemistry, ecology, and global carbon budgets. Gas exchange in medium- to large-sized lakes is largely regulated by wind; yet less is known about processes regulating gas transfer in small ponds where wind speeds are low. In this study, we determined the gas transfer velocity, k600, in four small ( < 250 m2 ) ponds by using a propane ( C3H8 ) gas injection. When estimated across 12 h periods, the average k600 ranged from 0.19 to 0.72 m d-1 across the ponds. We also estimated k600 at 2 to 3 h intervals during the day and evaluated the relationship with environmental conditions. The average daytime k600 ranged from 0.33 to 1.83 m d-1 across the ponds and was best predicted by wind speed and air or air-water temperature; however, the explanatory power was weak (R2 < 0.27) with high variability within and among ponds. To compare our results to larger water bodies, we compiled direct measurements of k600 from 67 ponds and lakes worldwide. Our k600 estimates were within the range of estimates for other small ponds, and variability in k600 increased with lake size. However, the majority of studies were conducted on medium-sized lakes (0.01 to 1 km2), leaving small ponds and large lakes understudied. Overall, this study adds four small ponds to the existing body of research on gas transfer velocities from inland waters and highlights uncertainty in k600, with implications for calculating metabolism and carbon emissions in inland waters. Title: Gas Transfer Velocities in Small Forested Ponds Author: Holgerson, Meredith A., Farr, Emily R., Raymond, Peter A. Year: 2017 Inland waters actively exchange gases with the atmosphere, and the gas exchange rate informs system biogeochemistry, ecology, and global carbon budgets. Gas exchange in medium- to large-sized lakes is largely regulated by wind; yet less is known about processes regulating gas transfer in small ponds where wind speeds are low. In this study, we determined the gas transfer velocity, k600, in four small ( < 250 m2 ) ponds by using a propane ( C3H8 ) gas injection. When estimated across 12 h periods, the average k600 ranged from 0.19 to 0.72 m d-1 across the ponds. We also estimated k600 at 2 to 3 h intervals during the day and evaluated the relationship with environmental conditions. The average daytime k600 ranged from 0.33 to 1.83 m d-1 across the ponds and was best predicted by wind speed and air or air-water temperature; however, the explanatory power was weak (R2 < 0.27) with high variability within and among ponds. To compare our results to larger water bodies, we compiled direct measurements of k600 from 67 ponds and lakes worldwide. Our k600 estimates were within the range of estimates for other small ponds, and variability in k600 increased with lake size. However, the majority of studies were conducted on medium-sized lakes (0.01 to 1 km2), leaving small ponds and large lakes understudied. Overall, this study adds four small ponds to the existing body of research on gas transfer velocities from inland waters and highlights uncertainty in k600, with implications for calculating metabolism and carbon emissions in inland waters. Close

• 2. [Article] Climate Change and Shifts in Water Related Ecosystem Services in the Tualatin and Yamhill River Basins

  Water related ecosystem services (WES), such as flow regulation, drinking water supply, temperature regulation, and water recreational activities, are affected by anthropogenic climate change. Forecasting ...

  Citation × Citation Citation Abstract Copy Title: Climate Change and Shifts in Water Related Ecosystem Services in the Tualatin and Yamhill River Basins Author: Chang, Heejun, Anthony, Terrance, Ennaanay, Driss, Sharma, Manu Year: 2011 Water related ecosystem services (WES), such as flow regulation, drinking water supply, temperature regulation, and water recreational activities, are affected by anthropogenic climate change. Forecasting potential shifts in such WES is critical to identifying the form and magnitude of likely impacts. We quantified the levels and values of WES under multiple climate change scenarios in the two watersheds located in the Portland metropolitan area, Oregon, USA using the combination of a hydrologic model Better Assessment Science Integrating point and Non-point Sources - Soil and Water Assessment Tool (BASINS-SWAT) and an ecosystem evaluation model ? Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST). Using the Intergovernmental Panel on Climate Change?s AR4 climate change simulation results, we found that there is a slight relative increase in annual water yield, sediment yield, and dissolved phosphorus, but storm peak management does not change substantially by the 2050s. Spatial analysis shows that the locations of hot and cold spots remain relatively stable. It is also shown that there are high spatial and temporal uncertainties associated with climate change projections due to variations in precipitation projections toward the middle of the 21st century. The findings of our study provide useful information for water and land managers in identifying target areas for conservation to best sustain WES provision, use, and value under a range of climate change scenarios. Title: Climate Change and Shifts in Water Related Ecosystem Services in the Tualatin and Yamhill River Basins Author: Chang, Heejun, Anthony, Terrance, Ennaanay, Driss, Sharma, Manu Year: 2011 Water related ecosystem services (WES), such as flow regulation, drinking water supply, temperature regulation, and water recreational activities, are affected by anthropogenic climate change. Forecasting potential shifts in such WES is critical to identifying the form and magnitude of likely impacts. We quantified the levels and values of WES under multiple climate change scenarios in the two watersheds located in the Portland metropolitan area, Oregon, USA using the combination of a hydrologic model Better Assessment Science Integrating point and Non-point Sources - Soil and Water Assessment Tool (BASINS-SWAT) and an ecosystem evaluation model ? Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST). Using the Intergovernmental Panel on Climate Change?s AR4 climate change simulation results, we found that there is a slight relative increase in annual water yield, sediment yield, and dissolved phosphorus, but storm peak management does not change substantially by the 2050s. Spatial analysis shows that the locations of hot and cold spots remain relatively stable. It is also shown that there are high spatial and temporal uncertainties associated with climate change projections due to variations in precipitation projections toward the middle of the 21st century. The findings of our study provide useful information for water and land managers in identifying target areas for conservation to best sustain WES provision, use, and value under a range of climate change scenarios. Close

• 3. [Article] Ecosystem Services as Boundary Objects for Transdisciplinary Collaboration

  The ecosystem services (ES) framework has potential to bring transdisciplinary teams together to achieve societal goals. Some label ES as “boundary objects” that help integrate diverse forms of knowledge ...

  Citation × Citation Citation Abstract Copy Title: Ecosystem Services as Boundary Objects for Transdisciplinary Collaboration Author: Steger, Cara, Hirsch, Shana, Evers, Cody, Branoff, Benjamin, Petrova, Maria, Nielsen-Pincus, Max, Wardropper, Chloe, van Riper, Carena J. Year: 2018 The ecosystem services (ES) framework has potential to bring transdisciplinary teams together to achieve societal goals. Some label ES as “boundary objects” that help integrate diverse forms of knowledge across social groups and organizational scales. However, this classification masks complexities that arise from unique characteristics of ES types (i.e., provisioning, regulating, and cultural), which influence their ability to function as boundary objects. We argue that interpretive flexibility and material structures interact in distinct ways across ES types throughout a boundary object “life cycle.” Viewing a 2015 U.S. federal memorandum as a catalyst, we critically evaluate the evolution of ES and its role as a boundary object. We propose that provisioning and regulating services are transitioning out of boundary object status, moving into a more standardized state. However, we anticipate that cultural services may continue to behave as boundary objects if collaborators maintain them as such. This shift in the functionality of ES as boundary objects is an important consideration for future research that attempts to reach across social worlds and disciplinary perspectives. We urge collaborations to rely on the most relevant disciplinary knowledge, rather than allowing the ease of standardized solutions to dictate the boundary of a given problem. Title: Ecosystem Services as Boundary Objects for Transdisciplinary Collaboration Author: Steger, Cara, Hirsch, Shana, Evers, Cody, Branoff, Benjamin, Petrova, Maria, Nielsen-Pincus, Max, Wardropper, Chloe, van Riper, Carena J. Year: 2018 The ecosystem services (ES) framework has potential to bring transdisciplinary teams together to achieve societal goals. Some label ES as “boundary objects” that help integrate diverse forms of knowledge across social groups and organizational scales. However, this classification masks complexities that arise from unique characteristics of ES types (i.e., provisioning, regulating, and cultural), which influence their ability to function as boundary objects. We argue that interpretive flexibility and material structures interact in distinct ways across ES types throughout a boundary object “life cycle.” Viewing a 2015 U.S. federal memorandum as a catalyst, we critically evaluate the evolution of ES and its role as a boundary object. We propose that provisioning and regulating services are transitioning out of boundary object status, moving into a more standardized state. However, we anticipate that cultural services may continue to behave as boundary objects if collaborators maintain them as such. This shift in the functionality of ES as boundary objects is an important consideration for future research that attempts to reach across social worlds and disciplinary perspectives. We urge collaborations to rely on the most relevant disciplinary knowledge, rather than allowing the ease of standardized solutions to dictate the boundary of a given problem. Close

• 4. [Article] Influence of Mixing and Buoyancy on Competition Between Cyanobacteria Species in Upper Klamath Lake

  Cyanobacterial blooms in lakes impact human health, the economy, and ecosystem health. It is predicted that climate change will promote and increase the frequency and intensity of cyanobacterial blooms ...

  Citation × Citation Citation Abstract Copy Title: Influence of Mixing and Buoyancy on Competition Between Cyanobacteria Species in Upper Klamath Lake Author: Brunkalla, Roberta Year: 2017 Cyanobacterial blooms in lakes impact human health, the economy, and ecosystem health. It is predicted that climate change will promote and increase the frequency and intensity of cyanobacterial blooms due to unique physiological adaptions that allow cyanobacteria to exploit warm stable water bodies. Key cyanobacteria physiological adaptions include nitrogen fixation, buoyancy regulation and higher optimum growth temperatures. The largest uncertainty of predicting the effect of climate change is in understanding how the interactions among species will change. Adding to the ambiguity, cyanobacteria physiological adaptions can vary based on lakespecific ecotypes and can have different sensitivities to temperature. It is critical to understand how cyanobacterial physiological adaptions impact species interactions in order to improve and devise adaptable, short‐term management methods for bloom control. This study investigated how weather patterns and algal buoyancy regulation influence the competition and accumulation of two bloom‐forming buoyant cyanobacteria species (Aphanizomenon flos‐aquae (APFA) and toxin‐forming Microcystis aeruginosa (MSAE)) in Upper Klamath Lake (UKL), Oregon. The focus was confirming the buoyancy rate of the APFA in Upper Klamath Lake and exploring whether short‐term weather conditions could lead to dangerous accumulations of APFA or MSAE. A sensitivity analysis was conducted on the model’s buoyancy terms and growth curves to see if the outcome of competition was influenced by these parameters. UKL specific buoyancy rates were measured on APFA from samples taken directly from the lake in the summer of 2015. Tracking software was used to measure APFA movement through water, and individual colony movement was averaged to obtain a single buoyancy rate. There was a high degree of agreement between the calculated APFA buoyancy rate in UKL (o.89 ± 0.34 m hr-1) with the rate published by Walsby (1995; 0.9 ± 0-.5 m hr-1). This study investigated how weather patterns and buoyancy regulation influenced the outcome of competition between APFA and MSAE. Weather and water column temperature data were collected from UKL in the summer of 2016. A onedimensional hydrodynamic model was used to calculate the lake’s thermal and turbulence structure on days with contrasting weather patterns (hot/cool and windy/calm). A competition model was used to calculate the accumulation of APFA and MSAE cells in regular intervals through the water column under the various weather scenarios. MSAE accumulation was significantly influenced by the thermal and turbulence regimes, but APFA maintained high accumulations under every regime and was the better competitor under every thermal and turbulence regime. MSAE was more negatively impacted by high turbulence than low temperatures. APFA’s optimum temperature growth curve was found to be important in determining the outcome of competition between APFA and MSAE. Surprisingly, competition was not sensitive to changes in buoyancy rates. Buoyancy was not found to be a function of algal accumulation under any thermal and turbulence regime. The impacts of climate change and human‐induced enrichment has the potential to change existing patterns of species interactions in lentic systems. Restoration and management efforts should consider the significance of cascading ecological responses to climate change. Understanding how key physiological adaptions operate is the first step to assessing the scope of this impact. While buoyancy might not play a large role in competition in UKL, it might be possible to use mixing to suppress MSAE because it is negatively impacted by high turbulence. If MSAE hot spots become a reoccurring problem in UKL, lakes managers might be able to use localized mixing to suppress MSAE blooms in these problem areas. Title: Influence of Mixing and Buoyancy on Competition Between Cyanobacteria Species in Upper Klamath Lake Author: Brunkalla, Roberta Year: 2017 Cyanobacterial blooms in lakes impact human health, the economy, and ecosystem health. It is predicted that climate change will promote and increase the frequency and intensity of cyanobacterial blooms due to unique physiological adaptions that allow cyanobacteria to exploit warm stable water bodies. Key cyanobacteria physiological adaptions include nitrogen fixation, buoyancy regulation and higher optimum growth temperatures. The largest uncertainty of predicting the effect of climate change is in understanding how the interactions among species will change. Adding to the ambiguity, cyanobacteria physiological adaptions can vary based on lakespecific ecotypes and can have different sensitivities to temperature. It is critical to understand how cyanobacterial physiological adaptions impact species interactions in order to improve and devise adaptable, short‐term management methods for bloom control. This study investigated how weather patterns and algal buoyancy regulation influence the competition and accumulation of two bloom‐forming buoyant cyanobacteria species (Aphanizomenon flos‐aquae (APFA) and toxin‐forming Microcystis aeruginosa (MSAE)) in Upper Klamath Lake (UKL), Oregon. The focus was confirming the buoyancy rate of the APFA in Upper Klamath Lake and exploring whether short‐term weather conditions could lead to dangerous accumulations of APFA or MSAE. A sensitivity analysis was conducted on the model’s buoyancy terms and growth curves to see if the outcome of competition was influenced by these parameters. UKL specific buoyancy rates were measured on APFA from samples taken directly from the lake in the summer of 2015. Tracking software was used to measure APFA movement through water, and individual colony movement was averaged to obtain a single buoyancy rate. There was a high degree of agreement between the calculated APFA buoyancy rate in UKL (o.89 ± 0.34 m hr-1) with the rate published by Walsby (1995; 0.9 ± 0-.5 m hr-1). This study investigated how weather patterns and buoyancy regulation influenced the outcome of competition between APFA and MSAE. Weather and water column temperature data were collected from UKL in the summer of 2016. A onedimensional hydrodynamic model was used to calculate the lake’s thermal and turbulence structure on days with contrasting weather patterns (hot/cool and windy/calm). A competition model was used to calculate the accumulation of APFA and MSAE cells in regular intervals through the water column under the various weather scenarios. MSAE accumulation was significantly influenced by the thermal and turbulence regimes, but APFA maintained high accumulations under every regime and was the better competitor under every thermal and turbulence regime. MSAE was more negatively impacted by high turbulence than low temperatures. APFA’s optimum temperature growth curve was found to be important in determining the outcome of competition between APFA and MSAE. Surprisingly, competition was not sensitive to changes in buoyancy rates. Buoyancy was not found to be a function of algal accumulation under any thermal and turbulence regime. The impacts of climate change and human‐induced enrichment has the potential to change existing patterns of species interactions in lentic systems. Restoration and management efforts should consider the significance of cascading ecological responses to climate change. Understanding how key physiological adaptions operate is the first step to assessing the scope of this impact. While buoyancy might not play a large role in competition in UKL, it might be possible to use mixing to suppress MSAE because it is negatively impacted by high turbulence. If MSAE hot spots become a reoccurring problem in UKL, lakes managers might be able to use localized mixing to suppress MSAE blooms in these problem areas. Close

• 5. [Article] Comparative Standards for Intensive Livestock Operations in Canada, Mexico, and the United States

  Livestock farming has been transformed in the past twenty years from a business dominated by relatively small producers to one dominated by large facilities raising thousands of animals. A side effect ...

  Citation × Citation Citation Abstract Copy Title: Comparative Standards for Intensive Livestock Operations in Canada, Mexico, and the United States Author: Speir, Jerry, Bowden, Marie-Ann, Ervin, David E., McElfish, Jim, Espejo, Rosario P., Whitehouse, Tim, Carpentier, Chantal L. Year: 2003 Livestock farming has been transformed in the past twenty years from a business dominated by relatively small producers to one dominated by large facilities raising thousands of animals. A side effect of this development has been a new set of environmental concerns unique to this industry. While regulation of livestock agriculture has historically been a state/provincial and local matter, governments from the local to the federal level have found themselves grappling with the issues created by these new, concentrated facilities. This Report surveys the current environmental requirements for "intensive livestock operations" (ILOs) in the United States, Mexico and Canada. The Report draws conclusions about current regulatory regimes and makes recommendations on the management of environmental issues associated with ILOs. Title: Comparative Standards for Intensive Livestock Operations in Canada, Mexico, and the United States Author: Speir, Jerry, Bowden, Marie-Ann, Ervin, David E., McElfish, Jim, Espejo, Rosario P., Whitehouse, Tim, Carpentier, Chantal L. Year: 2003 Livestock farming has been transformed in the past twenty years from a business dominated by relatively small producers to one dominated by large facilities raising thousands of animals. A side effect of this development has been a new set of environmental concerns unique to this industry. While regulation of livestock agriculture has historically been a state/provincial and local matter, governments from the local to the federal level have found themselves grappling with the issues created by these new, concentrated facilities. This Report surveys the current environmental requirements for "intensive livestock operations" (ILOs) in the United States, Mexico and Canada. The Report draws conclusions about current regulatory regimes and makes recommendations on the management of environmental issues associated with ILOs. Close

• 6. [Article] Water Flow through Temperate Glaciers

  Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier-induced floods, and the prediction of runoff from glacierized ...

  Citation × Citation Citation Abstract Copy Title: Water Flow through Temperate Glaciers Author: Fountain, Andrew G., Walder, Joseph S. Year: 1998 Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier-induced floods, and the prediction of runoff from glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn-free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, spawned by water flow along the bottoms of near-surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a limited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. Their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open-channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically. An upglacier branching, arborescent network of channels incised into the basal ice conveys water rapidly. Much of the water flux to the bed probably enters directly into the arborescent channel network, which covers only a small fraction of the glacier bed. More extensive spatially is a nonarborescent network, which commonly includes cavities (gaps between the glacier sole and bed), channels incised into the bed, and a layer of permeable sediment. The nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system. The arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network. The volume of water stored by a glacier varies diurnally and seasonally. Small, temperate alpine glaciers seem to attain a maximum seasonal water storage of approximately 200 mm of water averaged over the area of the glacier bed, with daily fluctuations of as much as 20-30 mm. The likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes, so most water storage may actually occur englacially. Stored water may also be released abruptly and catastrophically in the form of outburst floods. Title: Water Flow through Temperate Glaciers Author: Fountain, Andrew G., Walder, Joseph S. Year: 1998 Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier-induced floods, and the prediction of runoff from glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn-free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, spawned by water flow along the bottoms of near-surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a limited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. Their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open-channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically. An upglacier branching, arborescent network of channels incised into the basal ice conveys water rapidly. Much of the water flux to the bed probably enters directly into the arborescent channel network, which covers only a small fraction of the glacier bed. More extensive spatially is a nonarborescent network, which commonly includes cavities (gaps between the glacier sole and bed), channels incised into the bed, and a layer of permeable sediment. The nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system. The arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network. The volume of water stored by a glacier varies diurnally and seasonally. Small, temperate alpine glaciers seem to attain a maximum seasonal water storage of approximately 200 mm of water averaged over the area of the glacier bed, with daily fluctuations of as much as 20-30 mm. The likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes, so most water storage may actually occur englacially. Stored water may also be released abruptly and catastrophically in the form of outburst floods. Close

• 7. [Article] An Investigation of Invasion: Boater Knowledge Concerning Aquatic Invasive Species and the Influence of the New Zealand Mud Snail on Benthic Food Webs

  Invasive species are second only to habitat loss as a leading cause of native species displacement and the management of invasive species costs hundreds of billions annually. Invasion is often conceptualized ...

  Citation × Citation Citation Abstract Copy Title: An Investigation of Invasion: Boater Knowledge Concerning Aquatic Invasive Species and the Influence of the New Zealand Mud Snail on Benthic Food Webs Author: Cimino, Samuel Anthony Year: 2016 Invasive species are second only to habitat loss as a leading cause of native species displacement and the management of invasive species costs hundreds of billions annually. Invasion is often conceptualized as a series of stages (Transport, Introduction, Establishment, and Spread), which encourages ecologists to isolate factors that might enable a species to pass from one stage to another and therefore guide prevention or impact management. This thesis addresses each stage of invasion and attempts to determine where management might succeed in preventing invasion or minimizing impacts. The transport and introduction of aquatic invasive species (AIS) was analyzed by conducting a three tier human subjects survey at Tenmile Lake, Oregon over a two year period in which a public boat wash station was built and installed. Assessing boater knowledge of AIS and understanding proper boat cleaning procedure is useful in determining the threat of transport and introduction as overland boater movements is a major vector of AIS. The comparison between pre- and post- boat wash surveys indicate that there is a disconnect between what boaters say they will do and how they actually behave. While 75.9% of boaters from the pre-survey claimed they would use a boat wash station at Tenmile Lake, only 38.5% of post-survey boaters were observed using the station. Furthermore, the surveys identified knowledge gaps of boaters' awareness of AIS. More than 20.0% of boaters surveyed could not verbally name any AIS. To better understand the establishment and spread stages of invasion, I examined the influence of a specific AIS, the New Zealand mud snail (Potamopyrgus antipodarum; NZMS), on benthic food webs throughout three very different aquatic ecosystems (lakes, rivers, and estuaries). Samples of benthic lake, river, and estuarine invertebrates were collected, identified, and counted, and stable isotope analyses (SIA) were conducted on several components of the food web. NZMS densities were found to be dynamic, with population densities fluctuating over time and between locations. A significant negative relationship between NZMS density and community diversity across all ecosystems was found. However, the densities of specific feeding groups had varying positive (omnivores) and negative (herbivores) correlations with NZMS densities. Furthermore, SIA indicated that NZMS don't appear to be competing with native macroinvertebrates for the same food source. NZMS were found to have different influences on each invaded ecosystem, thus management of this particular AIS is difficult once established and spreading. The results of this thesis suggest that prevention of the transport and introduction of NZMS needs to be the focus for future management. Preventative management should include public outreach regarding AIS and proper boat cleaning procedure, and management should also emphasize the need for regional policies and regulations on the transport of AIS rather than site or state specific policies and regulations. Title: An Investigation of Invasion: Boater Knowledge Concerning Aquatic Invasive Species and the Influence of the New Zealand Mud Snail on Benthic Food Webs Author: Cimino, Samuel Anthony Year: 2016 Invasive species are second only to habitat loss as a leading cause of native species displacement and the management of invasive species costs hundreds of billions annually. Invasion is often conceptualized as a series of stages (Transport, Introduction, Establishment, and Spread), which encourages ecologists to isolate factors that might enable a species to pass from one stage to another and therefore guide prevention or impact management. This thesis addresses each stage of invasion and attempts to determine where management might succeed in preventing invasion or minimizing impacts. The transport and introduction of aquatic invasive species (AIS) was analyzed by conducting a three tier human subjects survey at Tenmile Lake, Oregon over a two year period in which a public boat wash station was built and installed. Assessing boater knowledge of AIS and understanding proper boat cleaning procedure is useful in determining the threat of transport and introduction as overland boater movements is a major vector of AIS. The comparison between pre- and post- boat wash surveys indicate that there is a disconnect between what boaters say they will do and how they actually behave. While 75.9% of boaters from the pre-survey claimed they would use a boat wash station at Tenmile Lake, only 38.5% of post-survey boaters were observed using the station. Furthermore, the surveys identified knowledge gaps of boaters' awareness of AIS. More than 20.0% of boaters surveyed could not verbally name any AIS. To better understand the establishment and spread stages of invasion, I examined the influence of a specific AIS, the New Zealand mud snail (Potamopyrgus antipodarum; NZMS), on benthic food webs throughout three very different aquatic ecosystems (lakes, rivers, and estuaries). Samples of benthic lake, river, and estuarine invertebrates were collected, identified, and counted, and stable isotope analyses (SIA) were conducted on several components of the food web. NZMS densities were found to be dynamic, with population densities fluctuating over time and between locations. A significant negative relationship between NZMS density and community diversity across all ecosystems was found. However, the densities of specific feeding groups had varying positive (omnivores) and negative (herbivores) correlations with NZMS densities. Furthermore, SIA indicated that NZMS don't appear to be competing with native macroinvertebrates for the same food source. NZMS were found to have different influences on each invaded ecosystem, thus management of this particular AIS is difficult once established and spreading. The results of this thesis suggest that prevention of the transport and introduction of NZMS needs to be the focus for future management. Preventative management should include public outreach regarding AIS and proper boat cleaning procedure, and management should also emphasize the need for regional policies and regulations on the transport of AIS rather than site or state specific policies and regulations. Close

• 8. [Article] Ecosystem Services in Managing Residential Landscapes: Priorities, Value Dimensions, and Cross-Regional Patterns

  Although ecosystem services have been intensively examined in certain domains (e.g., forests and wetlands), little research has assessed ecosystem services for the most dominant landscape type in urban ...

  Citation × Citation Citation Abstract Copy Title: Ecosystem Services in Managing Residential Landscapes: Priorities, Value Dimensions, and Cross-Regional Patterns Author: Larson, Kelli L., Morse, Jennifer L., Groffman, Peter M., Bettez, Neil D., Trammell, Tara Year: 2016 Although ecosystem services have been intensively examined in certain domains (e.g., forests and wetlands), little research has assessed ecosystem services for the most dominant landscape type in urban ecosystems—namely, residential yards. In this paper, we report findings of a cross-site survey of homeowners in six U.S. cities to 1) examine how residents subjectively value various ecosystem services, 2) explore distinctive dimensions of those values, and 3) test the urban homogenization hypothesis. This hypothesis posits that urbanization leads to similarities in the social-ecological dynamics across cities in diverse biomes. By extension, the thesis suggests that residents’ ecosystem service priorities for residential landscapes will be similar regardless of whether residents live in the humid East or the arid West, or the warm South or the cold North. Results underscored that cultural services were of utmost importance, particularly anthropocentric values including aesthetics, low-maintenance, and personal enjoyment. Using factor analyses, distinctive dimensions of residents’ values were found to partially align with the Millennium Ecosystem Assessment’s categories (provisioning, regulating, supporting, and cultural). Finally, residents’ ecosystem service priorities exhibited significant homogenization across regions. In particular, the traditional lawn aesthetic (neat, green, weed-free yards) was similarly important across residents of diverse U.S. cities. Only a few exceptions were found across different environmental and social contexts; for example, cooling effects were more important in the warm South, where residents also valued aesthetics more than those in the North, where low-maintenance yards were a greater priority. Title: Ecosystem Services in Managing Residential Landscapes: Priorities, Value Dimensions, and Cross-Regional Patterns Author: Larson, Kelli L., Morse, Jennifer L., Groffman, Peter M., Bettez, Neil D., Trammell, Tara Year: 2016 Although ecosystem services have been intensively examined in certain domains (e.g., forests and wetlands), little research has assessed ecosystem services for the most dominant landscape type in urban ecosystems—namely, residential yards. In this paper, we report findings of a cross-site survey of homeowners in six U.S. cities to 1) examine how residents subjectively value various ecosystem services, 2) explore distinctive dimensions of those values, and 3) test the urban homogenization hypothesis. This hypothesis posits that urbanization leads to similarities in the social-ecological dynamics across cities in diverse biomes. By extension, the thesis suggests that residents’ ecosystem service priorities for residential landscapes will be similar regardless of whether residents live in the humid East or the arid West, or the warm South or the cold North. Results underscored that cultural services were of utmost importance, particularly anthropocentric values including aesthetics, low-maintenance, and personal enjoyment. Using factor analyses, distinctive dimensions of residents’ values were found to partially align with the Millennium Ecosystem Assessment’s categories (provisioning, regulating, supporting, and cultural). Finally, residents’ ecosystem service priorities exhibited significant homogenization across regions. In particular, the traditional lawn aesthetic (neat, green, weed-free yards) was similarly important across residents of diverse U.S. cities. Only a few exceptions were found across different environmental and social contexts; for example, cooling effects were more important in the warm South, where residents also valued aesthetics more than those in the North, where low-maintenance yards were a greater priority. Close

• 9. [Article] Climate Change Decreases Nitrogen Pools and Mineralization Rates in Northern Hardwood Forests

  Nitrogen (N) supply often limits the productivity of temperate forests and is regulated by a complex mix of biological and climatic drivers. In excess, N is linked to a variety of soil, water, and air ...

  Citation × Citation Citation Abstract Copy Title: Climate Change Decreases Nitrogen Pools and Mineralization Rates in Northern Hardwood Forests Author: Durán, Jorge, Morse, Jennifer L., Groffman, Peter M., Campbell, John L., Christenson, Lynn M., Driscoll, Charles T., Fahey, Timothy J., Fisk, Melany C., Likens, Gene E., Melillo, Jerry M., Mitchell, Myron J., Templer, Pamela H., Vadeboncoeur, Matthew A. Year: 2016 Nitrogen (N) supply often limits the productivity of temperate forests and is regulated by a complex mix of biological and climatic drivers. In excess, N is linked to a variety of soil, water, and air pollution issues. Here, we use results from an elevation gradient study and historical data from the long-term Hubbard Brook Ecosystem Study (New Hampshire, USA) to examine relationships between changes in climate, especially during winter, and N supply to northern hardwood forest ecosystems. Low elevation plots with less snow, more soil freezing, and more freeze/thaw cycles supported lower rates of N mineralization than high elevation plots, despite having higher soil temperatures and no consistent differences in soil moisture during the growing season. These results are consistent with historical analyses showing decreases in rates of soil N mineralization and inorganic N concentrations since 1973 that are correlated with long-term increases in mean annual temperature, decreases in annual snow accumulation, and a increases in the number of winter thawing degree days. This evidence suggests that changing climate may be driving decreases in the availability of a key nutrient in northern hardwood forests, which could decrease ecosystem production but have positive effects on environmental consequences of excess N. Title: Climate Change Decreases Nitrogen Pools and Mineralization Rates in Northern Hardwood Forests Author: Durán, Jorge, Morse, Jennifer L., Groffman, Peter M., Campbell, John L., Christenson, Lynn M., Driscoll, Charles T., Fahey, Timothy J., Fisk, Melany C., Likens, Gene E., Melillo, Jerry M., Mitchell, Myron J., Templer, Pamela H., Vadeboncoeur, Matthew A. Year: 2016 Nitrogen (N) supply often limits the productivity of temperate forests and is regulated by a complex mix of biological and climatic drivers. In excess, N is linked to a variety of soil, water, and air pollution issues. Here, we use results from an elevation gradient study and historical data from the long-term Hubbard Brook Ecosystem Study (New Hampshire, USA) to examine relationships between changes in climate, especially during winter, and N supply to northern hardwood forest ecosystems. Low elevation plots with less snow, more soil freezing, and more freeze/thaw cycles supported lower rates of N mineralization than high elevation plots, despite having higher soil temperatures and no consistent differences in soil moisture during the growing season. These results are consistent with historical analyses showing decreases in rates of soil N mineralization and inorganic N concentrations since 1973 that are correlated with long-term increases in mean annual temperature, decreases in annual snow accumulation, and a increases in the number of winter thawing degree days. This evidence suggests that changing climate may be driving decreases in the availability of a key nutrient in northern hardwood forests, which could decrease ecosystem production but have positive effects on environmental consequences of excess N. Close

• 10. [Article] A Numerical Model Investigation of the Role of the Glacier Bed in Regulating Grounding Line Retreat of Thwaites Glacier, West Antarctica

  I examine how two different realizations of bed morphology affect Thwaites Glacier response to ocean warming through the initiation of marine ice sheet instability and associated grounding line retreat. ...

  Citation × Citation Citation Abstract Copy Title: A Numerical Model Investigation of the Role of the Glacier Bed in Regulating Grounding Line Retreat of Thwaites Glacier, West Antarctica Author: Waibel, Michael Scott Year: 2017 I examine how two different realizations of bed morphology affect Thwaites Glacier response to ocean warming through the initiation of marine ice sheet instability and associated grounding line retreat. A state of the art numerical ice sheet model is used for this purpose. The bed configurations used are the 1-km resolution interpolated BEDMAP2 bed and a higher-resolution conditional simulation produced by John Goff at the University of Texas using th e same underlying data. The model is forced using a slow ramp approach, where melt of ice on the floating side of the grounding line is increased over time, which gently nudges the glacier toward instability. Once an instability is initiated, the anomalous forcing is turned off, and further grounding line retreat is tracked. Two model experiments are conducted. The first experiment examines the effect of different anomalous forcing magnitudes over the same bed. The second experiment compares the generation and progress of instabilities over different beds. Two fundamental conclusions emerge from these experiments. First, different bed geometries require different ocean forcings to generate a genuine instability, where ice dynamics lead to a positive feedback and grounding line retreat becomes unstable. Second, slightly different forcings produce different retreat rates, even after the anomalous forcing is shut off, because different forcing magnitudes produce different driving stresses at the time the instability is initiated. While variability in the retreat rate over time depends on bed topography, the rate itself is set by the magnitude of the forcing. This signals the importance of correct knowledge of both bed shape and ocean circulation under floating portions of Antarctic ice sheets. The experiments also imply that different ocean warming rates delivered by different global warming scenarios directly affects the rate of Antarctic contribution to sea level rise. Title: A Numerical Model Investigation of the Role of the Glacier Bed in Regulating Grounding Line Retreat of Thwaites Glacier, West Antarctica Author: Waibel, Michael Scott Year: 2017 I examine how two different realizations of bed morphology affect Thwaites Glacier response to ocean warming through the initiation of marine ice sheet instability and associated grounding line retreat. A state of the art numerical ice sheet model is used for this purpose. The bed configurations used are the 1-km resolution interpolated BEDMAP2 bed and a higher-resolution conditional simulation produced by John Goff at the University of Texas using th e same underlying data. The model is forced using a slow ramp approach, where melt of ice on the floating side of the grounding line is increased over time, which gently nudges the glacier toward instability. Once an instability is initiated, the anomalous forcing is turned off, and further grounding line retreat is tracked. Two model experiments are conducted. The first experiment examines the effect of different anomalous forcing magnitudes over the same bed. The second experiment compares the generation and progress of instabilities over different beds. Two fundamental conclusions emerge from these experiments. First, different bed geometries require different ocean forcings to generate a genuine instability, where ice dynamics lead to a positive feedback and grounding line retreat becomes unstable. Second, slightly different forcings produce different retreat rates, even after the anomalous forcing is shut off, because different forcing magnitudes produce different driving stresses at the time the instability is initiated. While variability in the retreat rate over time depends on bed topography, the rate itself is set by the magnitude of the forcing. This signals the importance of correct knowledge of both bed shape and ocean circulation under floating portions of Antarctic ice sheets. The experiments also imply that different ocean warming rates delivered by different global warming scenarios directly affects the rate of Antarctic contribution to sea level rise. Close