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• 1. [Article] Plant Nitrogen Concentration and Isotopic Composition in Residential Lawns Across Seven US Cities

  Human drivers are often proposed to be stronger than biophysical drivers in influencing ecosystem structure and function in highly urbanized areas. In residential land cover, private yards are influenced ...

  Citation × Citation Citation Abstract Copy Title: Plant Nitrogen Concentration and Isotopic Composition in Residential Lawns Across Seven US Cities Author: Trammell, Tara, Pataki, Diane E., Cavender-Bares, Jeannine, Groffman, Peter M., Hall, Sharon J. Year: 2016 Human drivers are often proposed to be stronger than biophysical drivers in influencing ecosystem structure and function in highly urbanized areas. In residential land cover, private yards are influenced by individual homeowner preferences and actions while also experiencing large-scale human and biophysical drivers. We studied plant nitrogen (%N) and N stable isotopic composition (δ15N) in residential yards and paired native ecosystems in seven cities across the US that span major ecological biomes and climatic regions: Baltimore, Boston, Los Angeles, Miami, Minneapolis-St. Paul, Phoenix, and Salt Lake City. We found that residential lawns in three cities had enriched plant δ15N (P < 0.03) and in six cities higher plant N (%) relative to the associated native ecosystems (P < 0.05). Plant δ15N was progressively depleted across a gradient of urban density classes in Baltimore and Boston (P < 0.05). Lawn fertilization was associated with depleted plant δ15N in Boston and Los Angeles (P < 0.05), and organic fertilizer additions were associated with enriched plant δ15N in Los Angeles and Salt Lake City (P < 0.04). Plant δ15N was significantly enriched as a function of housing age in Baltimore (r2 = 0.27, P < 0.02), Boston (r2 = 0.27, P < 0.01), and Los Angeles (r2 = 0.34, P < 0.01). These patterns in plant δ15N and plant N (%) across these cities suggests that N sources to lawns, as well as greater rates of N cycling combined with subsequent N losses, may be important drivers of plant N dynamics in lawn ecosystems at the national scale. Title: Plant Nitrogen Concentration and Isotopic Composition in Residential Lawns Across Seven US Cities Author: Trammell, Tara, Pataki, Diane E., Cavender-Bares, Jeannine, Groffman, Peter M., Hall, Sharon J. Year: 2016 Human drivers are often proposed to be stronger than biophysical drivers in influencing ecosystem structure and function in highly urbanized areas. In residential land cover, private yards are influenced by individual homeowner preferences and actions while also experiencing large-scale human and biophysical drivers. We studied plant nitrogen (%N) and N stable isotopic composition (δ15N) in residential yards and paired native ecosystems in seven cities across the US that span major ecological biomes and climatic regions: Baltimore, Boston, Los Angeles, Miami, Minneapolis-St. Paul, Phoenix, and Salt Lake City. We found that residential lawns in three cities had enriched plant δ15N (P < 0.03) and in six cities higher plant N (%) relative to the associated native ecosystems (P < 0.05). Plant δ15N was progressively depleted across a gradient of urban density classes in Baltimore and Boston (P < 0.05). Lawn fertilization was associated with depleted plant δ15N in Boston and Los Angeles (P < 0.05), and organic fertilizer additions were associated with enriched plant δ15N in Los Angeles and Salt Lake City (P < 0.04). Plant δ15N was significantly enriched as a function of housing age in Baltimore (r2 = 0.27, P < 0.02), Boston (r2 = 0.27, P < 0.01), and Los Angeles (r2 = 0.34, P < 0.01). These patterns in plant δ15N and plant N (%) across these cities suggests that N sources to lawns, as well as greater rates of N cycling combined with subsequent N losses, may be important drivers of plant N dynamics in lawn ecosystems at the national scale. Close

• 2. [Article] Convergence of Microclimate in Residential Landscapes Across Diverse Cities in the United States

  Context The urban heat island (UHI) is a welldocumented pattern of warming in cities relative to rural areas. Most UHI research utilizes remote sensing methods at large scales, or climate sensors in single ...

  Citation × Citation Citation Abstract Copy Title: Convergence of Microclimate in Residential Landscapes Across Diverse Cities in the United States Author: Hall, Sharon J., Learned, J, Ruddell, Benjamin, Larson, Kelli L., Cavender-Bares, Jeannine, Bettez, Neil D., Groffman, Peter M., Grove, J. Morgan, Heffernan, James B., Hobbie, Sarah E., Larson, Kristen, Morse, Jennifer L., Neill, Christopher, Nelson, Kristen C., O'Neil-Dunne, Jarlath, Ogden, Laura A., Pataki, Diane E., Pearse, William D., Polsky, Colin, Chowdhury, Rinku Roy, Steele, Meredith K., Trammell, Tara Year: 2015 Context The urban heat island (UHI) is a welldocumented pattern of warming in cities relative to rural areas. Most UHI research utilizes remote sensing methods at large scales, or climate sensors in single cities surrounded by standardized land cover. Relatively few studies have explored continental-scale climatic patterns within common urban microenvironments such as residential landscapes that may affect human comfort. Objectives We tested the urban homogenization hypothesis which states that structure and function in cities exhibit ecological ‘‘sameness’’ across diverse regions relative to the native ecosystems they replaced. Methods We deployed portable micrometeorological sensors to compare air temperature and humidity in residential yards and native landscapes across six U.S. cities that span a range of climates (Phoenix, AZ; Los Angeles, CA; Minneapolis-St. Paul, MN; Boston, MA; Baltimore, MD; and Miami, FL). Results Microclimate in residential ecosystems was more similar among cities than among native ecosystems, particularly during the calm morning hours. Maximum regional actual evapotranspiration (AET) was related to the morning residential microclimate effect. Residential yards in cities with maximum AET \50–65 cm/year (Phoenix and Los Angeles) were generally cooler and more humid than nearby native shrublands during summer mornings, while yards in cities above this threshold were generally warmer (Baltimore and Miami) and drier (Miami) than native forests. On average, temperature and absolute humidity were *6 % less variable among residential ecosystems than among native ecosystems from diverse regions. Conclusions These data suggest that common residential land cover and structural characteristics lead to microclimatic convergence across diverse regions at the continental scale. Title: Convergence of Microclimate in Residential Landscapes Across Diverse Cities in the United States Author: Hall, Sharon J., Learned, J, Ruddell, Benjamin, Larson, Kelli L., Cavender-Bares, Jeannine, Bettez, Neil D., Groffman, Peter M., Grove, J. Morgan, Heffernan, James B., Hobbie, Sarah E., Larson, Kristen, Morse, Jennifer L., Neill, Christopher, Nelson, Kristen C., O'Neil-Dunne, Jarlath, Ogden, Laura A., Pataki, Diane E., Pearse, William D., Polsky, Colin, Chowdhury, Rinku Roy, Steele, Meredith K., Trammell, Tara Year: 2015 Context The urban heat island (UHI) is a welldocumented pattern of warming in cities relative to rural areas. Most UHI research utilizes remote sensing methods at large scales, or climate sensors in single cities surrounded by standardized land cover. Relatively few studies have explored continental-scale climatic patterns within common urban microenvironments such as residential landscapes that may affect human comfort. Objectives We tested the urban homogenization hypothesis which states that structure and function in cities exhibit ecological ‘‘sameness’’ across diverse regions relative to the native ecosystems they replaced. Methods We deployed portable micrometeorological sensors to compare air temperature and humidity in residential yards and native landscapes across six U.S. cities that span a range of climates (Phoenix, AZ; Los Angeles, CA; Minneapolis-St. Paul, MN; Boston, MA; Baltimore, MD; and Miami, FL). Results Microclimate in residential ecosystems was more similar among cities than among native ecosystems, particularly during the calm morning hours. Maximum regional actual evapotranspiration (AET) was related to the morning residential microclimate effect. Residential yards in cities with maximum AET \50–65 cm/year (Phoenix and Los Angeles) were generally cooler and more humid than nearby native shrublands during summer mornings, while yards in cities above this threshold were generally warmer (Baltimore and Miami) and drier (Miami) than native forests. On average, temperature and absolute humidity were *6 % less variable among residential ecosystems than among native ecosystems from diverse regions. Conclusions These data suggest that common residential land cover and structural characteristics lead to microclimatic convergence across diverse regions at the continental scale. Close

• 3. [Article] Ecosystem Recovery in Estuarine Wetlands of the Columbia River Estuary

  In the restoration of tidal wetland ecosystems, potential drivers of plant community development range from biotic controls (e.g. plant competition, seed dispersal) to abiotic controls (e.g. tidal flooding, ...

  Citation × Citation Citation Abstract Copy Title: Ecosystem Recovery in Estuarine Wetlands of the Columbia River Estuary Author: Kidd, Sarah Ann Year: 2017 In the restoration of tidal wetland ecosystems, potential drivers of plant community development range from biotic controls (e.g. plant competition, seed dispersal) to abiotic controls (e.g. tidal flooding, salinity levels). How these controls influence the success of tidal wetland restoration are only partly understood, but have important implications for wetland habitat recovery. Specifically, the extent to which the existing native and non-native seed banks in tidally reconnected wetlands interact with these controls is not clear, yet the potential success of passive restoration methods depends upon this understanding. For a 54-year chronosequence of eleven tidal wetland restoration sites in the Lower Columbia River of western Oregon, USA, it was hypothesized that native plant species and soil properties would show trends approaching reference levels within 3 to 20 years post-restoration and that lower elevation wetland areas within restored sites would exhibit a greater native species abundance and similarity to reference sites, compared with restored high elevation wetland areas. Results indicated that plant species richness, soil organic matter, bulk density, pH, and salinity conditions among the restoration sites reached reference wetland ranges within 3-6 years post-tidal reconnection. The mid-low marsh elevation zones (2.5 m) remained dominated by non-native species Phalaris arundinacea and Juncus effusus subsp. effusus. To investigate the mechanisms driving these non-native plant invasions, it was hypothesized that native and non-native wetland plant community distributions would be reflective both of their abundance in the seed bank and of their germination tolerance to wetland tidal flooding and salinity conditions. Using a factorial study design of three tidal conditions by three salinity levels, these hypotheses were tested in the greenhouse. Overall, non-native seeds were found to significantly outnumber native seeds in both seed banks. In the greenhouse, P. arundinacea and J. effusus were found to germinate more readily out of the seed bank under freshwater high-marsh flooding (1 hour a day) treatments as compared to oligohaline (3 ppt) mid-low marsh flooding (3-6 hours twice a day) treatments and to brackish salinity (10 ppt) treatments. Dominant native wetland species, Carex lyngbyei and Schoenoplectus lacustris, germination were not found to vary significantly among the treatments (p > 0.10). These results indicate that the salinity and flooding gradients within these restored marshes suppress germination of the non-native species in the low-mid marsh but not in the high marsh, where they are likely able to outcompete the native species due to their dominance in the seed bank. The implications of these results for passive tidal wetland restoration efforts are that both seed bank composition and species-specific tolerances to restored tidal flooding and salinity gradients are key mechanisms driving native and non-native plant community development and resilience. Title: Ecosystem Recovery in Estuarine Wetlands of the Columbia River Estuary Author: Kidd, Sarah Ann Year: 2017 In the restoration of tidal wetland ecosystems, potential drivers of plant community development range from biotic controls (e.g. plant competition, seed dispersal) to abiotic controls (e.g. tidal flooding, salinity levels). How these controls influence the success of tidal wetland restoration are only partly understood, but have important implications for wetland habitat recovery. Specifically, the extent to which the existing native and non-native seed banks in tidally reconnected wetlands interact with these controls is not clear, yet the potential success of passive restoration methods depends upon this understanding. For a 54-year chronosequence of eleven tidal wetland restoration sites in the Lower Columbia River of western Oregon, USA, it was hypothesized that native plant species and soil properties would show trends approaching reference levels within 3 to 20 years post-restoration and that lower elevation wetland areas within restored sites would exhibit a greater native species abundance and similarity to reference sites, compared with restored high elevation wetland areas. Results indicated that plant species richness, soil organic matter, bulk density, pH, and salinity conditions among the restoration sites reached reference wetland ranges within 3-6 years post-tidal reconnection. The mid-low marsh elevation zones (2.5 m) remained dominated by non-native species Phalaris arundinacea and Juncus effusus subsp. effusus. To investigate the mechanisms driving these non-native plant invasions, it was hypothesized that native and non-native wetland plant community distributions would be reflective both of their abundance in the seed bank and of their germination tolerance to wetland tidal flooding and salinity conditions. Using a factorial study design of three tidal conditions by three salinity levels, these hypotheses were tested in the greenhouse. Overall, non-native seeds were found to significantly outnumber native seeds in both seed banks. In the greenhouse, P. arundinacea and J. effusus were found to germinate more readily out of the seed bank under freshwater high-marsh flooding (1 hour a day) treatments as compared to oligohaline (3 ppt) mid-low marsh flooding (3-6 hours twice a day) treatments and to brackish salinity (10 ppt) treatments. Dominant native wetland species, Carex lyngbyei and Schoenoplectus lacustris, germination were not found to vary significantly among the treatments (p > 0.10). These results indicate that the salinity and flooding gradients within these restored marshes suppress germination of the non-native species in the low-mid marsh but not in the high marsh, where they are likely able to outcompete the native species due to their dominance in the seed bank. The implications of these results for passive tidal wetland restoration efforts are that both seed bank composition and species-specific tolerances to restored tidal flooding and salinity gradients are key mechanisms driving native and non-native plant community development and resilience. Close

• 4. [Article] Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters

  Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. ...

  Citation × Citation Citation Abstract Copy Title: Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters Author: Strecker, Angela L., Olden, Julian D. Year: 2014 Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. Title: Fish Species Introductions Provide Novel Insights into the Patterns and Drivers of Phylogenetic Structure in Freshwaters Author: Strecker, Angela L., Olden, Julian D. Year: 2014 Despite long-standing interest of terrestrial ecologists, freshwater ecosystems are a fertile, yet unappreciated, testing ground for applying community phylogenetics to uncover mechanisms of species assembly. We quantify phylogenetic clustering and overdispersion of native and non-native fishes of a large river basin in the American Southwest to test for the mechanisms (environmental filtering versus competitive exclusion) and spatial scales influencing community structure. Contrary to expectations, non-native species were phylogenetically clustered and related to natural environmental conditions, whereas native species were not phylogenetically structured, likely reflecting human-related changes to the basin. The species that are most invasive (in terms of ecological impacts) tended to be the most phylogenetically divergent from natives across watersheds, but not within watersheds, supporting the hypothesis that Darwin's naturalization conundrum is driven by the spatial scale. Phylogenetic distinctiveness may facilitate non-native establishment at regional scales, but environmental filtering restricts local membership to closely related species with physiological tolerances for current environments. By contrast, native species may have been phylogenetically clustered in historical times, but species loss from contemporary populations by anthropogenic activities has likely shaped the phylogenetic signal. Our study implies that fundamental mechanisms of community assembly have changed, with fundamental consequences for the biogeography of both native and non-native species. Close

• 5. [Article] Beer, fish and water restoration certificates : a new way to restore rivers in Montana

  2 pages

  Citation × Citation Citation Abstract Copy Title: Beer, fish and water restoration certificates : a new way to restore rivers in Montana Author: University of Oregon. Ecosystem Workforce Program Year: 2016, 2013 2 pages Title: Beer, fish and water restoration certificates : a new way to restore rivers in Montana Author: University of Oregon. Ecosystem Workforce Program Year: 2016, 2013 2 pages Close

• 6. [Article] Riparian Wetland Plant Response to Livestock Exclusion in the Lower Columbia River Basin

  The purpose of this study was to examine the characteristics of riparian plant communities along a gradient of livestock exclusion in the Lower Columbia River Basin (LCRB) located in the Pacific Northwest ...

  Citation × Citation Citation Abstract Copy Title: Riparian Wetland Plant Response to Livestock Exclusion in the Lower Columbia River Basin Author: Kidd, S. A., Yeakley, J. Alan Year: 2015 The purpose of this study was to examine the characteristics of riparian plant communities along a gradient of livestock exclusion in the Lower Columbia River Basin (LCRB) located in the Pacific Northwest region of the United States. Livestock exclusion from riparian wetlands is a common passive restoration technique. Few studies, however, have focused on the effects of livestock grazing or the exclusion of livestock grazing on these ecosystems. Vegetation community composition was examined in two passive restoration sites, three and 13 years since livestock exclusion, and in a reference site with continued livestock grazing. We hypothesized native plant species richness would be lower in the excluded wetlands than in the grazed wetland due to the competitive exclusion from an increase in non-native plant dominance in the absence of grazing. The grazed wetland had significantly (P < 0.02) greater mean total species richness (23.3 ± 1.6; mean ± 1 standard error), native (10.2 ± 0.5), and non-native (12 ± 1.5) species richness than both the excluded wetlands. Mean total species richness did not differ significantly (P = 0.088) between the three-year (12 ± 1.4) and 13-year (5.5 ± 2.3) excluded wetlands. Mean native and non-native species richness also did not differ significantly (native P = 0.088. non-native P = 0.064) between the three-year (native 6.3 ± 0.6, non-native 5 ± 2.3) and 13-year (native 2.8 ± 1.3, non-native 2.7 ± 1.1) excluded wetlands. However, native species abundance as indicated by percent cover was significantly (P < 0.02) lower in the 13-year excluded wetland (4.2 ± 2.0%) than both the three-year excluded (51.5 ± 3.9%) and grazed (23.2 ± 3.3%) wetlands. The invasive grass, Phalaris arundinacea (reed canarygrass), was found to be the dominant vegetation cover in all three wetlands, with average relative cover ranging from 95.2 ± 2.0% at the 13-year exclusion site to 52.8 ± 4.1% at the grazing site, and 43.0 ± 4.0% cover at the three-year exclusion site. These observations suggest that livestock exclusion alone may be an ineffective strategy for restoring riparian plant communities in regions such as LCRB where invasive species like reed canarygrass are abundant. More effective management alternatives might include short-term livestock exclusion and reintroduced targeted grazing to both reduce livestock impacts and control reed canarygrass dominance. Title: Riparian Wetland Plant Response to Livestock Exclusion in the Lower Columbia River Basin Author: Kidd, S. A., Yeakley, J. Alan Year: 2015 The purpose of this study was to examine the characteristics of riparian plant communities along a gradient of livestock exclusion in the Lower Columbia River Basin (LCRB) located in the Pacific Northwest region of the United States. Livestock exclusion from riparian wetlands is a common passive restoration technique. Few studies, however, have focused on the effects of livestock grazing or the exclusion of livestock grazing on these ecosystems. Vegetation community composition was examined in two passive restoration sites, three and 13 years since livestock exclusion, and in a reference site with continued livestock grazing. We hypothesized native plant species richness would be lower in the excluded wetlands than in the grazed wetland due to the competitive exclusion from an increase in non-native plant dominance in the absence of grazing. The grazed wetland had significantly (P < 0.02) greater mean total species richness (23.3 ± 1.6; mean ± 1 standard error), native (10.2 ± 0.5), and non-native (12 ± 1.5) species richness than both the excluded wetlands. Mean total species richness did not differ significantly (P = 0.088) between the three-year (12 ± 1.4) and 13-year (5.5 ± 2.3) excluded wetlands. Mean native and non-native species richness also did not differ significantly (native P = 0.088. non-native P = 0.064) between the three-year (native 6.3 ± 0.6, non-native 5 ± 2.3) and 13-year (native 2.8 ± 1.3, non-native 2.7 ± 1.1) excluded wetlands. However, native species abundance as indicated by percent cover was significantly (P < 0.02) lower in the 13-year excluded wetland (4.2 ± 2.0%) than both the three-year excluded (51.5 ± 3.9%) and grazed (23.2 ± 3.3%) wetlands. The invasive grass, Phalaris arundinacea (reed canarygrass), was found to be the dominant vegetation cover in all three wetlands, with average relative cover ranging from 95.2 ± 2.0% at the 13-year exclusion site to 52.8 ± 4.1% at the grazing site, and 43.0 ± 4.0% cover at the three-year exclusion site. These observations suggest that livestock exclusion alone may be an ineffective strategy for restoring riparian plant communities in regions such as LCRB where invasive species like reed canarygrass are abundant. More effective management alternatives might include short-term livestock exclusion and reintroduced targeted grazing to both reduce livestock impacts and control reed canarygrass dominance. Close

• 7. [Article] Transforming Cemeteries: A Framework for Enhancing Ecosystem Processes and Human Uses In Formerly Rural, Urban Cemeteries.

  88 pages. Examining committee chair: David Hulse

  Citation × Citation Citation Abstract Copy Title: Transforming Cemeteries: A Framework for Enhancing Ecosystem Processes and Human Uses In Formerly Rural, Urban Cemeteries. Author: Tromp van Holst, Katherine Year: 2016 88 pages. Examining committee chair: David Hulse Title: Transforming Cemeteries: A Framework for Enhancing Ecosystem Processes and Human Uses In Formerly Rural, Urban Cemeteries. Author: Tromp van Holst, Katherine Year: 2016 88 pages. Examining committee chair: David Hulse Close

• 8. [Article] Non-native Mangroves of Moloka'i, Hawai'i: A Socio-ecological Analysis

  Invasive species are recognized as a leading threat to ecosystems and their management is expensive, time consuming, and labor intensive. Therefore, it is important to review both benefits and detriments ...

  Citation × Citation Citation Abstract Copy Title: Non-native Mangroves of Moloka'i, Hawai'i: A Socio-ecological Analysis Author: Lewis, Casey Year: 2017 Invasive species are recognized as a leading threat to ecosystems and their management is expensive, time consuming, and labor intensive. Therefore, it is important to review both benefits and detriments of the species to inform appropriate management decisions. Red mangrove was introduced to Moloka'i, Hawaii in 1902 to mitigate the effects of soil erosion and has since spread along the coast and to adjacent islands creating novel habitat. This study assessed both biological services and social attitudes towards Moloka'i's non-native mangroves to provide a comprehensive evaluation of the species. Zooplankton community structure was examined in mangrove and non-mangrove sites and found to be different depending on the amount of mangroves present. Surveys of Moloka'i residents revealed no majority attitude towards mangroves nor support for complete eradication but residents were highly supportive of active management. Approaching other novel ecosystems created by established non-native species from a socio-ecological view may become more crucial as changes in climate, demographics, and environmental conditions further complicate effects. In our globalized world, non-native species introductions will continue to have both positive and negative effects that vary over time. Therefore, assessment of both social and ecological perspectives may lead to more effective management with greater community support. Title: Non-native Mangroves of Moloka'i, Hawai'i: A Socio-ecological Analysis Author: Lewis, Casey Year: 2017 Invasive species are recognized as a leading threat to ecosystems and their management is expensive, time consuming, and labor intensive. Therefore, it is important to review both benefits and detriments of the species to inform appropriate management decisions. Red mangrove was introduced to Moloka'i, Hawaii in 1902 to mitigate the effects of soil erosion and has since spread along the coast and to adjacent islands creating novel habitat. This study assessed both biological services and social attitudes towards Moloka'i's non-native mangroves to provide a comprehensive evaluation of the species. Zooplankton community structure was examined in mangrove and non-mangrove sites and found to be different depending on the amount of mangroves present. Surveys of Moloka'i residents revealed no majority attitude towards mangroves nor support for complete eradication but residents were highly supportive of active management. Approaching other novel ecosystems created by established non-native species from a socio-ecological view may become more crucial as changes in climate, demographics, and environmental conditions further complicate effects. In our globalized world, non-native species introductions will continue to have both positive and negative effects that vary over time. Therefore, assessment of both social and ecological perspectives may lead to more effective management with greater community support. Close

• 9. [Article] Examination of Human Impacts on the Biodiversity and Ecology of Lichen and Moss Communities

  Globally, more than half of the world's population is living in urban areas and it is well accepted that human activities (e.g. climate warming, pollution, landscape homogenization) pose a multitude of ...

  Citation × Citation Citation Abstract Copy Title: Examination of Human Impacts on the Biodiversity and Ecology of Lichen and Moss Communities Author: Prather, Hannah Marie Year: 2017 Globally, more than half of the world's population is living in urban areas and it is well accepted that human activities (e.g. climate warming, pollution, landscape homogenization) pose a multitude of threats to ecosystems. Largely, human-related impacts on biodiversity will hold consequences for larger ecological processes and research looking into human impacts on sensitive epiphytic lichen and moss communities is an emerging area of research. While seemingly small, lichen and moss communities exist on nearly every terrestrial ecosystem on Earth and contribute to whole-system processes (e.g. hydrology, mineral cycling, food web energetics) worldwide. To further examine human impacts on epiphytic communities, I conducted three studies examining urbanization and climate warming effects on epiphytic lichen and moss biodiversity and ecology. In the first study I revisited a historic urban lichen community study to assess how urban lichen communities have responded to regional air quality changes occurring over the last nearly two decades. I further investigated, for the first time, the biodiversity of urban tree canopy-dwelling lichen communities in a native coniferous tree species, Pseudotsuga menziesii. I found that urban parks and forested areas harbor a species rich community of lichens epiphytes. Further, I found evidence for the distinct homogenization of urban epiphytic lichen communities, suggesting that expanding beyond simplistic measures of biodiversity to consider community composition and functional biodiversity may be necessary when assessing the ecology and potential ecosystem services of epiphyte communites within urbanizing landscapes. Next, I present the first tall tree canopy study across a regional gradient of urbanization near Portland, Oregon, USA. I found that tall tree canopy epiphyte communities change dramatically along gradients of increasing urbanization, most notably by the transitioning of species functional groups from sensitive, oligotrophic species to a dominance of urban-tolerant, eutrophic species. The implications these dramatic shifts in species composition have on essential PNW ecosystem processes, like N-fixation and canopy microclimate regulation, is still not well understood and is difficult to formally evaluate. However, I find strong evidence that native conifer trees in urban areas may provide a diversity of essential ecosystem services, including providing stratified habitat for epiphyte communities and their associated micro arthropod communities and the scavenging of atmospherically deposited nutrients. Future work is needed to understand how losses in canopy N fixation and species with large biomass (both lichens and bryophytes) will affect nutrient and hydrologic cycling in the PNW region, which continue to undergo rapid growth and urbanization. The final chapter investigates the impacts of passive warming by Open Top Chambers (OTCs) in moss-dominated ecosystems located on the Western Antarctic Peninsula, an area of increasing climate warming. I compared species-specific temperature effects, moss canopy morphology, sexual reproductive effort and invertebrate communities between OTC and control moss communities for two moss species, Polytrichastrum alpinum and Sanionia uncinata, that make up over 65% of the terrestrial vegetative cover in the area. I found distinct reproductive shifts in P. alpinum under passive warming compared to controls. Moss communities under warming also had substantially larger total invertebrate communities than those in control moss communities, and invertebrate communities were significantly affected by moss species and moss reproductive effort. Further, substantial species-specific thermal differences among contiguous patches of these dominant moss species were revealed. These results suggest that continued warming will differentially impact the reproductive output of Antarctic moss species and is likely to dramatically alter terrestrial ecosystems dynamics from the bottom up. This combined work provides a diverse contribution to the field of epiphyte ecology and biology by providing new insights on how human impacts will affect epiphyte lichen and moss communities across diverse ecosystems, in light of a rapidly changing planet. Title: Examination of Human Impacts on the Biodiversity and Ecology of Lichen and Moss Communities Author: Prather, Hannah Marie Year: 2017 Globally, more than half of the world's population is living in urban areas and it is well accepted that human activities (e.g. climate warming, pollution, landscape homogenization) pose a multitude of threats to ecosystems. Largely, human-related impacts on biodiversity will hold consequences for larger ecological processes and research looking into human impacts on sensitive epiphytic lichen and moss communities is an emerging area of research. While seemingly small, lichen and moss communities exist on nearly every terrestrial ecosystem on Earth and contribute to whole-system processes (e.g. hydrology, mineral cycling, food web energetics) worldwide. To further examine human impacts on epiphytic communities, I conducted three studies examining urbanization and climate warming effects on epiphytic lichen and moss biodiversity and ecology. In the first study I revisited a historic urban lichen community study to assess how urban lichen communities have responded to regional air quality changes occurring over the last nearly two decades. I further investigated, for the first time, the biodiversity of urban tree canopy-dwelling lichen communities in a native coniferous tree species, Pseudotsuga menziesii. I found that urban parks and forested areas harbor a species rich community of lichens epiphytes. Further, I found evidence for the distinct homogenization of urban epiphytic lichen communities, suggesting that expanding beyond simplistic measures of biodiversity to consider community composition and functional biodiversity may be necessary when assessing the ecology and potential ecosystem services of epiphyte communites within urbanizing landscapes. Next, I present the first tall tree canopy study across a regional gradient of urbanization near Portland, Oregon, USA. I found that tall tree canopy epiphyte communities change dramatically along gradients of increasing urbanization, most notably by the transitioning of species functional groups from sensitive, oligotrophic species to a dominance of urban-tolerant, eutrophic species. The implications these dramatic shifts in species composition have on essential PNW ecosystem processes, like N-fixation and canopy microclimate regulation, is still not well understood and is difficult to formally evaluate. However, I find strong evidence that native conifer trees in urban areas may provide a diversity of essential ecosystem services, including providing stratified habitat for epiphyte communities and their associated micro arthropod communities and the scavenging of atmospherically deposited nutrients. Future work is needed to understand how losses in canopy N fixation and species with large biomass (both lichens and bryophytes) will affect nutrient and hydrologic cycling in the PNW region, which continue to undergo rapid growth and urbanization. The final chapter investigates the impacts of passive warming by Open Top Chambers (OTCs) in moss-dominated ecosystems located on the Western Antarctic Peninsula, an area of increasing climate warming. I compared species-specific temperature effects, moss canopy morphology, sexual reproductive effort and invertebrate communities between OTC and control moss communities for two moss species, Polytrichastrum alpinum and Sanionia uncinata, that make up over 65% of the terrestrial vegetative cover in the area. I found distinct reproductive shifts in P. alpinum under passive warming compared to controls. Moss communities under warming also had substantially larger total invertebrate communities than those in control moss communities, and invertebrate communities were significantly affected by moss species and moss reproductive effort. Further, substantial species-specific thermal differences among contiguous patches of these dominant moss species were revealed. These results suggest that continued warming will differentially impact the reproductive output of Antarctic moss species and is likely to dramatically alter terrestrial ecosystems dynamics from the bottom up. This combined work provides a diverse contribution to the field of epiphyte ecology and biology by providing new insights on how human impacts will affect epiphyte lichen and moss communities across diverse ecosystems, in light of a rapidly changing planet. Close

• 10. [Article] The Limitation of Spread of Non-native Marine Invertebrates from Artificial Structures to Natural Habitats

  Artificial structures created for aquatic anthropogenic activities are often colonized and fouled by many non-native species, few of which have invaded natural areas. Some research has indicated predation ...

  Citation × Citation Citation Abstract Copy Title: The Limitation of Spread of Non-native Marine Invertebrates from Artificial Structures to Natural Habitats Author: McClees, Whitney, de Rivera, Catherine E. Year: 2017 Artificial structures created for aquatic anthropogenic activities are often colonized and fouled by many non-native species, few of which have invaded natural areas. Some research has indicated predation is limiting the spread of non-native species, while other research has indicated that it is dispersal-driven. To determine the effects of dispersal limitation and predation on the risk to surrounding habitats of being invaded by non-native species established on marina docks, we used a three-factor design, deploying seven unglazed ceramic panels per each treatment combination of 1) inside versus outside a marina in Yaquina Bay, Oregon; 2) cage keeping out predators >mesh size, no cage, or partial cage; 3) fixed near the substrata (benthic) versus floating 1m below the surface. We also moved panels of either adults or recruits from floating in the marina to any of the treatment combinations to test if they would have lower survival outside by the substrate. The community on panels suspended in the marina only minimally overlapped with panels outside of the marina near the bottom. However, there was no difference between the cage treatments, which suggests that predators excluded by the cages are not responsible for the observed differences in species richness or composition. Title: The Limitation of Spread of Non-native Marine Invertebrates from Artificial Structures to Natural Habitats Author: McClees, Whitney, de Rivera, Catherine E. Year: 2017 Artificial structures created for aquatic anthropogenic activities are often colonized and fouled by many non-native species, few of which have invaded natural areas. Some research has indicated predation is limiting the spread of non-native species, while other research has indicated that it is dispersal-driven. To determine the effects of dispersal limitation and predation on the risk to surrounding habitats of being invaded by non-native species established on marina docks, we used a three-factor design, deploying seven unglazed ceramic panels per each treatment combination of 1) inside versus outside a marina in Yaquina Bay, Oregon; 2) cage keeping out predators >mesh size, no cage, or partial cage; 3) fixed near the substrata (benthic) versus floating 1m below the surface. We also moved panels of either adults or recruits from floating in the marina to any of the treatment combinations to test if they would have lower survival outside by the substrate. The community on panels suspended in the marina only minimally overlapped with panels outside of the marina near the bottom. However, there was no difference between the cage treatments, which suggests that predators excluded by the cages are not responsible for the observed differences in species richness or composition. Close