Search

Search Results

• 51. [Article] Contrasting distribution patterns of invasive and naturalized non-native species along environmental gradients in a semi-arid montane ecosystem

  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 article is copyrighted by International Association ...

  Citation × Citation Citation Abstract Copy Title: Contrasting distribution patterns of invasive and naturalized non-native species along environmental gradients in a semi-arid montane ecosystem Author: Andersen, Kelly M., Endress, Bryan A., Parks, Catherine G., Naylor, Bridgett J. 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 article is copyrighted by International Association for Vegetation Science and published by John Wiley & Sons, Ltd.. It can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291654-109X Title: Contrasting distribution patterns of invasive and naturalized non-native species along environmental gradients in a semi-arid montane ecosystem Author: Andersen, Kelly M., Endress, Bryan A., Parks, Catherine G., Naylor, Bridgett J. 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 article is copyrighted by International Association for Vegetation Science and published by John Wiley & Sons, Ltd.. It can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291654-109X Close

• 52. [Image] Klamath Falls Resource Area resource management plan and environmental impact statement : final : Volume 1

  	Proposed resource management plan/final environmental impact statement for the Klamath Falls Resource Area
  	Citation × Citation Citation Abstract Copy Title: Klamath Falls Resource Area resource management plan and environmental impact statement : final : Volume 1 Author: United States. Bureau of Land Management. Klamath Falls Resource Area Office Year: 1994, 2005, 2004 Proposed resource management plan/final environmental impact statement for the Klamath Falls Resource Area Title: Klamath Falls Resource Area resource management plan and environmental impact statement : final : Volume 1 Author: United States. Bureau of Land Management. Klamath Falls Resource Area Office Year: 1994, 2005, 2004 Proposed resource management plan/final environmental impact statement for the Klamath Falls Resource Area Close

• 53. [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

• 54. [Article] Investigating temporal patterns of a native bee community in a remnant North American bunchgrass prairie using blue vane traps

  This is the publisher’s final pdf. The published article is copyrighted by University of Wisconsin Digital Collections Center and can be found at: http://www.insectscience.org/.

  Citation × Citation Citation Abstract Copy Title: Investigating temporal patterns of a native bee community in a remnant North American bunchgrass prairie using blue vane traps Author: Rao, Sujaya, Stephen, William P., Kimoto, Chiho, Thorp, Robbin W., DeBano, Sandra J. This is the publisher’s final pdf. The published article is copyrighted by University of Wisconsin Digital Collections Center and can be found at: http://www.insectscience.org/. Title: Investigating temporal patterns of a native bee community in a remnant North American bunchgrass prairie using blue vane traps Author: Rao, Sujaya, Stephen, William P., Kimoto, Chiho, Thorp, Robbin W., DeBano, Sandra J. This is the publisher’s final pdf. The published article is copyrighted by University of Wisconsin Digital Collections Center and can be found at: http://www.insectscience.org/. Close

• 55. [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

• 56. [Article] Re-examining the relationship between invasive lionfish and native grouper in the Caribbean

  This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by PeerJ. The published article can be found at: https://peerj.com/.

  Citation × Citation Citation Abstract Copy Title: Re-examining the relationship between invasive lionfish and native grouper in the Caribbean Author: Hackerott, Serena, Valdivia, Abel, Bruno, John F., Cox, Courtney E., Green, Stephanie J. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by PeerJ. The published article can be found at: https://peerj.com/. Title: Re-examining the relationship between invasive lionfish and native grouper in the Caribbean Author: Hackerott, Serena, Valdivia, Abel, Bruno, John F., Cox, Courtney E., Green, Stephanie J. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by PeerJ. The published article can be found at: https://peerj.com/. Close

• 57. [Article] Butterfly and flower community composition among prairie-oak ecosystem habitats in the Willamette Valley, Oregon

  Prairie-oak ecosystems in the Willamette Valley, Oregon have experienced habitat loss and degradation; most of these ecosystems are fragmented into smaller patches. Prairie-oak butterfly species, in the ...

  Citation × Citation Citation Abstract Copy Title: Butterfly and flower community composition among prairie-oak ecosystem habitats in the Willamette Valley, Oregon Author: Powers, Breanna F. Prairie-oak ecosystems in the Willamette Valley, Oregon have experienced habitat loss and degradation; most of these ecosystems are fragmented into smaller patches. Prairie-oak butterfly species, in the Willamette Valley, have decreased dramatically due to loss or degradation of habitat. More research is needed on sustaining the populations of butterflies in prairie-oak ecosystems. The purpose of my study was to examine the role prairie-oak habitats have in structuring butterfly communities in the Willamette Valley. My objectives were to: (1) assess how butterfly community structure and species composition (density, abundance, and species richness) varies along an oak canopy cover gradient in order to understand the role of habitat type in structuring butterfly communities in prairie-oak ecosystems; (2) characterize community composition of nectar resources and environmental variables known to be important for butterfly species. I also investigated temporal and structural relationships between butterfly and flower communities. I found that butterfly abundance and density were greater (p < 0.02) in prairies than in oak savannas or oak woodlands; however, species richness did not differ among habitats (p = 0.54). Ordination of prairie-oak habitats in butterfly species space with a joint plot overlay of environmental variables revealed several strong correlations; butterfly community structure was negatively correlated with litter and oak canopy cover and positively correlated to vegetation cover. The prairie, oak savanna, and oak woodland habitat types differed in nectar species community structure, though this difference was small. Non-native species were some of the most abundant flowers species found in all stands. Butterfly communities were positively related to flower communities. I detected significant seasonal patterns among the habitat types in butterfly and flower communities. Prairies appear to be the most important habitat for native butterfly populations compared to oak savanna and oak woodlands. Flowers were most prevalent in prairies and prairies had the highest percentage of native flower species; the prevalence of non-native flower species was greatest in oak woodlands. My study may represent a short-term community transition as a result of management or it may represent a more permanent community. Further study is needed to understand the effects of different management strategies for habitat restoration and the presence of non-native flower species on butterflies in prairie-oak ecosystems in the Willamette Valley. Title: Butterfly and flower community composition among prairie-oak ecosystem habitats in the Willamette Valley, Oregon Author: Powers, Breanna F. Prairie-oak ecosystems in the Willamette Valley, Oregon have experienced habitat loss and degradation; most of these ecosystems are fragmented into smaller patches. Prairie-oak butterfly species, in the Willamette Valley, have decreased dramatically due to loss or degradation of habitat. More research is needed on sustaining the populations of butterflies in prairie-oak ecosystems. The purpose of my study was to examine the role prairie-oak habitats have in structuring butterfly communities in the Willamette Valley. My objectives were to: (1) assess how butterfly community structure and species composition (density, abundance, and species richness) varies along an oak canopy cover gradient in order to understand the role of habitat type in structuring butterfly communities in prairie-oak ecosystems; (2) characterize community composition of nectar resources and environmental variables known to be important for butterfly species. I also investigated temporal and structural relationships between butterfly and flower communities. I found that butterfly abundance and density were greater (p < 0.02) in prairies than in oak savannas or oak woodlands; however, species richness did not differ among habitats (p = 0.54). Ordination of prairie-oak habitats in butterfly species space with a joint plot overlay of environmental variables revealed several strong correlations; butterfly community structure was negatively correlated with litter and oak canopy cover and positively correlated to vegetation cover. The prairie, oak savanna, and oak woodland habitat types differed in nectar species community structure, though this difference was small. Non-native species were some of the most abundant flowers species found in all stands. Butterfly communities were positively related to flower communities. I detected significant seasonal patterns among the habitat types in butterfly and flower communities. Prairies appear to be the most important habitat for native butterfly populations compared to oak savanna and oak woodlands. Flowers were most prevalent in prairies and prairies had the highest percentage of native flower species; the prevalence of non-native flower species was greatest in oak woodlands. My study may represent a short-term community transition as a result of management or it may represent a more permanent community. Further study is needed to understand the effects of different management strategies for habitat restoration and the presence of non-native flower species on butterflies in prairie-oak ecosystems in the Willamette Valley. Close

• 58. [Article] Quantifying the Potential of Native Plants for Improving Pollination and Biological Control in Agroecosystems

  Agricultural areas can be inhospitable to the attraction and maintenance of beneficial insects like natural enemies and pollinators and this can result in a decrease in the ecosystem services of pollination ...

  Citation × Citation Citation Abstract Copy Title: Quantifying the Potential of Native Plants for Improving Pollination and Biological Control in Agroecosystems Author: Winfield, Tammy L. Agricultural areas can be inhospitable to the attraction and maintenance of beneficial insects like natural enemies and pollinators and this can result in a decrease in the ecosystem services of pollination and pest control that these insects supply. If habitat can be created and maintained on-farm, an increase in the numbers and diversity of beneficial insects could be seen which could correspond to an increase in ecosystem services. This study was undertaken to quantify what insect communities are supported by a set of native Oregon plants and to test for differences in the relative attractiveness of plant species to three broad categories of insects: herbivores, natural enemies, and pollinators. This first season of research shows that plant species vary in their relative attractiveness to the three functional groups of insects. Some of this variation is likely related to differences in flowering phenology. There was a significant positive association between percent peak bloom and the number of natural enemies collected on a particular plant species. The numbers of natural enemies, herbivores, and pollinators collected on plant species also varied across sites, suggesting that landscape characteristics also influence the insect communities associated with particular plant species. Title: Quantifying the Potential of Native Plants for Improving Pollination and Biological Control in Agroecosystems Author: Winfield, Tammy L. Agricultural areas can be inhospitable to the attraction and maintenance of beneficial insects like natural enemies and pollinators and this can result in a decrease in the ecosystem services of pollination and pest control that these insects supply. If habitat can be created and maintained on-farm, an increase in the numbers and diversity of beneficial insects could be seen which could correspond to an increase in ecosystem services. This study was undertaken to quantify what insect communities are supported by a set of native Oregon plants and to test for differences in the relative attractiveness of plant species to three broad categories of insects: herbivores, natural enemies, and pollinators. This first season of research shows that plant species vary in their relative attractiveness to the three functional groups of insects. Some of this variation is likely related to differences in flowering phenology. There was a significant positive association between percent peak bloom and the number of natural enemies collected on a particular plant species. The numbers of natural enemies, herbivores, and pollinators collected on plant species also varied across sites, suggesting that landscape characteristics also influence the insect communities associated with particular plant species. Close

• 59. [Article] Non-native and native plant species distributions and variability along an elevation gradient in the Wallowa Mountains, Oregon

  Invasion by non-native plants into natural areas is an important component of global change that threatens biodiversity and ecosystem structure and function. Mountains are currently among the least invaded ...

  Citation × Citation Citation Abstract Copy Title: Non-native and native plant species distributions and variability along an elevation gradient in the Wallowa Mountains, Oregon Author: Averett, Joshua P. Invasion by non-native plants into natural areas is an important component of global change that threatens biodiversity and ecosystem structure and function. Mountains are currently among the least invaded ecosystems, however, these biodiversity hotspots are increasingly under threat of exotic plant invasion. Evaluation of plant species distribution patterns in mountain ecosystems can provide insight into dominant processes of plant invasion and inform management to reduce the spread of non-native plants in mountains. The objectives of this study were to: 1) evaluate the main drivers of plant invasions in the Wallowa Mountain Range of northeastern Oregon, and the extent patterns of native species distributions and their causes differed from non-native species along an elevation gradient; and 2) investigate inter- and intra-annual understory vascular plant species variability along an elevation gradient to inform long-term monitoring of plant invasion dynamics in the Wallowa Mountains. We sampled understory vascular plant communities in summer 2012 along three forest roads in the Wallowa Mountains. Transects (n=20) were evenly stratified by elevation (60 meters) along each road. Indicator species analysis (ISA) was used to identify habitat tendencies for non-native species. Non-metric multidimensional scaling (NMS) related community composition to environmental and species trait factors. Predictors of non-native and native species abundance and richness were evaluated using Non-parametric multiplicative regression (NPMR). Canopy openness and elevation niche widths were modeled for all common species and evaluated for evidence of high elevation or closed canopy specialization. Non-native species richness decreased continuously with increasing elevation. In contrast, native species richness displayed a unimodal distribution with maximum richness at the mid-elevations. According to NMS and NPMR, elevation, canopy openness, and disturbance were the strongest correlates of non-native species abundance. Non-native species were concentrated in low elevation bunchgrass, roadside, and open forest habitats with high canopy openness, and moderate to high disturbance intensity. Overlays of species trait factors onto ordinations revealed that the transition into the subalpine community and over-story canopy closure exceeding approximately 60 percent were potential barriers to non-native species establishment. Vegetation sampling was repeated three times (June, July, and August 2013) during the growing season in summer 2013 for a subset (n=10) of our transects. Blocked Multi Response Permutation Procedure (MRBP) was used to test the hypothesis of no change in species composition between years (summer 2012 and summer 2013) and between each sampling period (June, July, and August) within one growing season. NMS related community composition at different times to environmental and trait category factors. Blocked Indicator Species Analysis was used to identify species with tendencies towards specific sampling periods. Important predictors of vegetation change were identified and indicator species distributions were related to NMS axes using NPMR. Vegetation composition changed both between years and between each sampling period within one growing season. Species richness increased with sampling effort, dominant species were consistently found throughout all sampling periods and rare species showed the highest rate of turnover between sampling periods. The highest species richness and greatest number of indicator species were associated with the early summer (June) sampling period. Approximately 25% of all non-native species showed tendencies towards a specific sampling period where greater than half favored the June sampling period within lowland bunchgrass communities. Annual species including the most dominant non-native species within the lowland and montane zones showed the highest inter- and intra-annual variability compared to other trait categories. Total species richness was positively related to turnover and was the most important predictor of relative abundance change between all sampling periods. Species turnover was highest in species rich montane plots; however, trait abundance and richness did not statistically differ in montane plots. These data suggest that elevation, canopy, openness, and disturbance are important factors structuring non-native plant distributions in the Wallowa Mountains. Our findings that non-native species tended to be concentrated in low elevation, early successional habitats coupled with a lack of high elevation or closed canopy specialization indicates that non-native plants that occurr at the highest elevations are likely generalist species that depend on disturbance (primarily open over-story canopy) for spread into higher elevation sites until they are eventually filtered out by harsh environmental conditions coincident with the subalpine transition zone. Collectively these results suggest that interactions between introduction pathways that favor human assisted dispersal into the low-elevations where ruderal species are favored and environmental filters (elevation, canopy openness, and disturbance) are the dominant factors structuring non-native plant distributions in the Wallowa Mountains. Our results also indicate that long-term monitoring of vegetation change in the Wallowa Mountains will be improved through periodic sampling during each growing season. Sampling once during the spring or early summer and then again coincident with peak biomass should improve estimates of species distributions and diversity patterns by capturing both vernal and late season species. Early season sampling may be particularly important for monitoring non-native plants in the Wallowa Mountains as most non-natives were concentrated in low elevation semiarid bunchgrass communities where spring and early summer specialization is common. Title: Non-native and native plant species distributions and variability along an elevation gradient in the Wallowa Mountains, Oregon Author: Averett, Joshua P. Invasion by non-native plants into natural areas is an important component of global change that threatens biodiversity and ecosystem structure and function. Mountains are currently among the least invaded ecosystems, however, these biodiversity hotspots are increasingly under threat of exotic plant invasion. Evaluation of plant species distribution patterns in mountain ecosystems can provide insight into dominant processes of plant invasion and inform management to reduce the spread of non-native plants in mountains. The objectives of this study were to: 1) evaluate the main drivers of plant invasions in the Wallowa Mountain Range of northeastern Oregon, and the extent patterns of native species distributions and their causes differed from non-native species along an elevation gradient; and 2) investigate inter- and intra-annual understory vascular plant species variability along an elevation gradient to inform long-term monitoring of plant invasion dynamics in the Wallowa Mountains. We sampled understory vascular plant communities in summer 2012 along three forest roads in the Wallowa Mountains. Transects (n=20) were evenly stratified by elevation (60 meters) along each road. Indicator species analysis (ISA) was used to identify habitat tendencies for non-native species. Non-metric multidimensional scaling (NMS) related community composition to environmental and species trait factors. Predictors of non-native and native species abundance and richness were evaluated using Non-parametric multiplicative regression (NPMR). Canopy openness and elevation niche widths were modeled for all common species and evaluated for evidence of high elevation or closed canopy specialization. Non-native species richness decreased continuously with increasing elevation. In contrast, native species richness displayed a unimodal distribution with maximum richness at the mid-elevations. According to NMS and NPMR, elevation, canopy openness, and disturbance were the strongest correlates of non-native species abundance. Non-native species were concentrated in low elevation bunchgrass, roadside, and open forest habitats with high canopy openness, and moderate to high disturbance intensity. Overlays of species trait factors onto ordinations revealed that the transition into the subalpine community and over-story canopy closure exceeding approximately 60 percent were potential barriers to non-native species establishment. Vegetation sampling was repeated three times (June, July, and August 2013) during the growing season in summer 2013 for a subset (n=10) of our transects. Blocked Multi Response Permutation Procedure (MRBP) was used to test the hypothesis of no change in species composition between years (summer 2012 and summer 2013) and between each sampling period (June, July, and August) within one growing season. NMS related community composition at different times to environmental and trait category factors. Blocked Indicator Species Analysis was used to identify species with tendencies towards specific sampling periods. Important predictors of vegetation change were identified and indicator species distributions were related to NMS axes using NPMR. Vegetation composition changed both between years and between each sampling period within one growing season. Species richness increased with sampling effort, dominant species were consistently found throughout all sampling periods and rare species showed the highest rate of turnover between sampling periods. The highest species richness and greatest number of indicator species were associated with the early summer (June) sampling period. Approximately 25% of all non-native species showed tendencies towards a specific sampling period where greater than half favored the June sampling period within lowland bunchgrass communities. Annual species including the most dominant non-native species within the lowland and montane zones showed the highest inter- and intra-annual variability compared to other trait categories. Total species richness was positively related to turnover and was the most important predictor of relative abundance change between all sampling periods. Species turnover was highest in species rich montane plots; however, trait abundance and richness did not statistically differ in montane plots. These data suggest that elevation, canopy, openness, and disturbance are important factors structuring non-native plant distributions in the Wallowa Mountains. Our findings that non-native species tended to be concentrated in low elevation, early successional habitats coupled with a lack of high elevation or closed canopy specialization indicates that non-native plants that occurr at the highest elevations are likely generalist species that depend on disturbance (primarily open over-story canopy) for spread into higher elevation sites until they are eventually filtered out by harsh environmental conditions coincident with the subalpine transition zone. Collectively these results suggest that interactions between introduction pathways that favor human assisted dispersal into the low-elevations where ruderal species are favored and environmental filters (elevation, canopy openness, and disturbance) are the dominant factors structuring non-native plant distributions in the Wallowa Mountains. Our results also indicate that long-term monitoring of vegetation change in the Wallowa Mountains will be improved through periodic sampling during each growing season. Sampling once during the spring or early summer and then again coincident with peak biomass should improve estimates of species distributions and diversity patterns by capturing both vernal and late season species. Early season sampling may be particularly important for monitoring non-native plants in the Wallowa Mountains as most non-natives were concentrated in low elevation semiarid bunchgrass communities where spring and early summer specialization is common. Close

• 60. [Article] The influence of biophysical feedbacks and species interactions on grass invasions and coastal dune morphology in the Pacific Northwest, USA

  Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially ...

  Citation × Citation Citation Abstract Copy Title: The influence of biophysical feedbacks and species interactions on grass invasions and coastal dune morphology in the Pacific Northwest, USA Author: Zarnetske, Phoebe Lehmann, 1979- Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially alter physical features in an environment, and this can lead to cascading effects on the biological community. Aquatic-terrestrial interface ecosystems are excellent systems to study the interactions among invasive ecosystem engineers, physical features, and biological communities, because interactions among vegetation, sediment, and fluids within biophysical feedbacks create and modify distinct physical features. Further, these systems provide important ecosystem services including coastal protection afforded by their natural features. In this dissertation, I investigate the interactions and feedbacks among sand-binding beach grass species (a native, Elymus mollis (Trin.), and two non-natives, Ammophila arenaria (L.) Link and A. breviligulata Fernald), sediment supply, and dune shape along the U.S. Pacific Northwest coast. Dunes dominated by A. arenaria tend to be taller and narrower compared to the shorter, wider dunes dominated by A. breviligulata. These patterns suggest an ecological control on dune shape, and thus, coastal vulnerability to overtopping waves. I investigate the causes and consequences of these patterns with experiments, field observations, and modeling. Specifically, I investigate the relative roles of vegetation and sediment supply in shaping coastal dunes over inter-annual and multi-decadal time scales (Chapter 2), characterize a biophysical feedback between beach grass species growth habit and sediment supply (Chapter 3), uncover the mechanisms leading to beach grass coexistence and whether A. breviligulata can invade and dominate new sections of coastline (Chapter 4), and examine the non-target effects resulting from management actions that remove Ammophila for the recovery of the threatened Western Snowy plover (Charadrius alexandrinus nivosus) (Chapter 5). I found that vegetation and sediment supply play important roles in dune shape changes across inter-annual and multi-decadal time scales (Chapter 2). I determined that a biophysical feedback between the beach grass growth habits and sediment supply results in species-specific differences in sand capture ability, and thus, is a likely explanation for differences in dune shape (Chapter 3). I found that all three beach grass species can coexist across different sediment deposition rates, and that this coexistence is largely mediated by positive direct and indirect species interactions. I further determined that A. breviligulata is capable of invading and dominating the beach grass community in regions where it is currently absent (Chapter 4). Combined, these findings indicate that A. breviligulata is an inferior dune building species as compared to A. arenaria, and suggest that in combination with sediment supply gradients, these species differences ultimately lead to differences in dune shape. Potential further invasions of A. breviligulata into southern regions of the Pacific Northwest may diminish the coastal protection ability of dunes currently dominated by A. arenaria, but this effect could be moderated by the predicted near co-dominance of A. arenaria in these lower sediment supply conditions. Finally, I found that the techniques used to remove Ammophila for plover recovery have unintended consequences for the native and endemic dune plant communities, and disrupt the natural disturbance regime of shifting sand. A whole-ecosystem restoration focus would be an improvement over the target-species approach, as it would promote the return of the natural disturbance regime, which in turn, would help recover the native biological community. The findings from this dissertation research provide a robust knowledge base that can guide further investigations of biological and physical changes to the coastal dunes, can help improve the management of dune ecosystem services and the restoration of native communities, and can help anticipate the impacts of future beach grass invasions and climate change induced changes to the coast. Title: The influence of biophysical feedbacks and species interactions on grass invasions and coastal dune morphology in the Pacific Northwest, USA Author: Zarnetske, Phoebe Lehmann, 1979- Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially alter physical features in an environment, and this can lead to cascading effects on the biological community. Aquatic-terrestrial interface ecosystems are excellent systems to study the interactions among invasive ecosystem engineers, physical features, and biological communities, because interactions among vegetation, sediment, and fluids within biophysical feedbacks create and modify distinct physical features. Further, these systems provide important ecosystem services including coastal protection afforded by their natural features. In this dissertation, I investigate the interactions and feedbacks among sand-binding beach grass species (a native, Elymus mollis (Trin.), and two non-natives, Ammophila arenaria (L.) Link and A. breviligulata Fernald), sediment supply, and dune shape along the U.S. Pacific Northwest coast. Dunes dominated by A. arenaria tend to be taller and narrower compared to the shorter, wider dunes dominated by A. breviligulata. These patterns suggest an ecological control on dune shape, and thus, coastal vulnerability to overtopping waves. I investigate the causes and consequences of these patterns with experiments, field observations, and modeling. Specifically, I investigate the relative roles of vegetation and sediment supply in shaping coastal dunes over inter-annual and multi-decadal time scales (Chapter 2), characterize a biophysical feedback between beach grass species growth habit and sediment supply (Chapter 3), uncover the mechanisms leading to beach grass coexistence and whether A. breviligulata can invade and dominate new sections of coastline (Chapter 4), and examine the non-target effects resulting from management actions that remove Ammophila for the recovery of the threatened Western Snowy plover (Charadrius alexandrinus nivosus) (Chapter 5). I found that vegetation and sediment supply play important roles in dune shape changes across inter-annual and multi-decadal time scales (Chapter 2). I determined that a biophysical feedback between the beach grass growth habits and sediment supply results in species-specific differences in sand capture ability, and thus, is a likely explanation for differences in dune shape (Chapter 3). I found that all three beach grass species can coexist across different sediment deposition rates, and that this coexistence is largely mediated by positive direct and indirect species interactions. I further determined that A. breviligulata is capable of invading and dominating the beach grass community in regions where it is currently absent (Chapter 4). Combined, these findings indicate that A. breviligulata is an inferior dune building species as compared to A. arenaria, and suggest that in combination with sediment supply gradients, these species differences ultimately lead to differences in dune shape. Potential further invasions of A. breviligulata into southern regions of the Pacific Northwest may diminish the coastal protection ability of dunes currently dominated by A. arenaria, but this effect could be moderated by the predicted near co-dominance of A. arenaria in these lower sediment supply conditions. Finally, I found that the techniques used to remove Ammophila for plover recovery have unintended consequences for the native and endemic dune plant communities, and disrupt the natural disturbance regime of shifting sand. A whole-ecosystem restoration focus would be an improvement over the target-species approach, as it would promote the return of the natural disturbance regime, which in turn, would help recover the native biological community. The findings from this dissertation research provide a robust knowledge base that can guide further investigations of biological and physical changes to the coastal dunes, can help improve the management of dune ecosystem services and the restoration of native communities, and can help anticipate the impacts of future beach grass invasions and climate change induced changes to the coast. Close