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Author: Sarah Jean Kiuama Frey Publisher: ISBN: Category : Bird communities Languages : en Pages : 138
Book Description
Population trends and patterns in species distributions are the major currencies used to examine responses by biodiversity to changing environments. Effective conservation recommendations require that models of both distribution dynamics and population trends accurately reflect reality. However, identification of the appropriate temporal and spatial scales of animal response, and then obtaining data at these scales present two major challenges to developing predictive models. In heterogeneous forested mountain landscapes I examined: A) the relative drivers of climatic variability at fine spatial scales under the forest canopy ('microclimate'), B) the influence of microclimate on local-scale occupancy dynamics of bird communities, and C) the effects of spatial scale and imperfect bird detection on long-term avian population trends. Climate change has been predicted to cause widespread biodiversity declines. However, the capacity of climate envelope models for predicting the future of biodiversity has been questioned due to the mismatch between the scale of available data (i.e., global climate models) and the scales at which organisms experience their environment. Local-scale variation in microclimate is hypothesized to provide potential 'microrefugia' for biodiversity, but the relative role of elevation, microtopography, and vegetation structure in driving microclimate is not well known. If the microrefugia hypothesis is true, I expected to see areas on the landscape that remained relatively cooler (i.e., buffered sites). To test this, I collected temperature data at 183 sites across elevation and forest structure gradients in complex terrain of the H.J. Andrews Experimental Forest in the Cascade Mountains of Oregon, USA (Chapter 2). I used boosted regression trees, a novel machine learning approach, to determine the relative influence of vegetation structure, microtopography, and elevation as drivers of microclimate and mapped fine-scale distributions of temperature across the landscape. Models performed extremely well on independent data - cross-validation correlations between testing and training data were 0.69 - 0.98 for ten selected climate variables. Elevation was the dominant driver in fine-scale microclimate patterns, although vegetation and microtopography also showed substantial relative influences. For instance, during the spring-summer transition, maximum monthly temperatures observed in old-growth sites were 2.6°C (95% CI: 1.8 - 3.3°C) cooler than plantation sites and minimum temperatures during winter months were 0.6°C (95% CI: 0.4 - 0.8°C) warmer. This suggests that older forest stands mediate changes in temperature by buffering against warming during summer months and moderating cold temperatures during the winter. Climate is generally considered most influential on species distributions at large spatial scales; however much microclimate variability exists within regional patterns. I tested whether this high degree of microclimate variability has relevance for predicting species distributions and occupancy dynamics of the Andrews Forest bird community. I collected bird occurrence data in 2012 and 2013 at all 183 sites with fine-scale temperature measurements. I used dynamic occupancy models to test the effects of temperature on occupancy and apparent within-season bird movement while statistically accounting for vegetation effects and imperfect bird detection (Chapter 3). Most species (87%) exhibited within-season shifts in response to local-scale temperature metrics. Effects of temperature on within-season occupancy dynamics were as large or larger (1 to 1.7 times) than vegetation. However, individual species were almost as likely to shift toward warmer sites as toward cooler sites, suggesting that microclimate preferences are species-specific. My results emphasize that high-resolution temperature data provide valuable insight into avian distribution dynamics in montane forest environments and that microclimate is an important variable in breeding season habitat selection by forest birds. I hypothesize that microclimate-associated distribution shifts may reflect species' potential for behavioral buffering from climate change in complex terrain. Factors influencing population trends often differ depending on the spatial scale under consideration. Further, accurate estimation of trends requires accounting for biases caused by imperfect detection. To test the degree to which population trends are consistent across scales, I estimated landscape-scale bird population trends from 1999-2012 for 38 species at the Hubbard Brook Experimental Forest (HBEF) in the White Mountains of New Hampshire, USA and compared them to regional and local trends (Chapter 4). I used a new method - open-population binomial mixture models - to test the hypothesis that imperfect detection in bird sampling has the potential to bias trend estimates. I also tested for generalities in species responses by predicting population trends as a function of life history and ecological traits. Landscape-scale trends were correlated with regional and local trends, but generally these correlations were weak (r = 0.12 - 0.4). Further, more species were declining at the regional scale compared to within the relatively undisturbed HBEF. Life history and ecological traits did not explain any of the variability in the HBEF trends. However, at the regional scale, species that occurred at higher elevations were more likely to be declining and species associated with older forests have increased. I hypothesize that these differences could be attributed to both elevated rates of land-use change in the broader region and the fact that the structure of regional data did not permit modeling of imperfect detection. Indeed, accounting for imperfect detection resulted in more accurate population trend estimates at the landscape scale; without accounting for detection we would have both missed trends and falsely identified trends where none existed. These results highlight two important cautions for trend analysis: 1) population trends estimated at fine spatial scales may not be extrapolated to broader scales and 2) accurate trends require accounting for imperfect detection.
Author: Sarah Jean Kiuama Frey Publisher: ISBN: Category : Bird communities Languages : en Pages : 138
Book Description
Population trends and patterns in species distributions are the major currencies used to examine responses by biodiversity to changing environments. Effective conservation recommendations require that models of both distribution dynamics and population trends accurately reflect reality. However, identification of the appropriate temporal and spatial scales of animal response, and then obtaining data at these scales present two major challenges to developing predictive models. In heterogeneous forested mountain landscapes I examined: A) the relative drivers of climatic variability at fine spatial scales under the forest canopy ('microclimate'), B) the influence of microclimate on local-scale occupancy dynamics of bird communities, and C) the effects of spatial scale and imperfect bird detection on long-term avian population trends. Climate change has been predicted to cause widespread biodiversity declines. However, the capacity of climate envelope models for predicting the future of biodiversity has been questioned due to the mismatch between the scale of available data (i.e., global climate models) and the scales at which organisms experience their environment. Local-scale variation in microclimate is hypothesized to provide potential 'microrefugia' for biodiversity, but the relative role of elevation, microtopography, and vegetation structure in driving microclimate is not well known. If the microrefugia hypothesis is true, I expected to see areas on the landscape that remained relatively cooler (i.e., buffered sites). To test this, I collected temperature data at 183 sites across elevation and forest structure gradients in complex terrain of the H.J. Andrews Experimental Forest in the Cascade Mountains of Oregon, USA (Chapter 2). I used boosted regression trees, a novel machine learning approach, to determine the relative influence of vegetation structure, microtopography, and elevation as drivers of microclimate and mapped fine-scale distributions of temperature across the landscape. Models performed extremely well on independent data - cross-validation correlations between testing and training data were 0.69 - 0.98 for ten selected climate variables. Elevation was the dominant driver in fine-scale microclimate patterns, although vegetation and microtopography also showed substantial relative influences. For instance, during the spring-summer transition, maximum monthly temperatures observed in old-growth sites were 2.6°C (95% CI: 1.8 - 3.3°C) cooler than plantation sites and minimum temperatures during winter months were 0.6°C (95% CI: 0.4 - 0.8°C) warmer. This suggests that older forest stands mediate changes in temperature by buffering against warming during summer months and moderating cold temperatures during the winter. Climate is generally considered most influential on species distributions at large spatial scales; however much microclimate variability exists within regional patterns. I tested whether this high degree of microclimate variability has relevance for predicting species distributions and occupancy dynamics of the Andrews Forest bird community. I collected bird occurrence data in 2012 and 2013 at all 183 sites with fine-scale temperature measurements. I used dynamic occupancy models to test the effects of temperature on occupancy and apparent within-season bird movement while statistically accounting for vegetation effects and imperfect bird detection (Chapter 3). Most species (87%) exhibited within-season shifts in response to local-scale temperature metrics. Effects of temperature on within-season occupancy dynamics were as large or larger (1 to 1.7 times) than vegetation. However, individual species were almost as likely to shift toward warmer sites as toward cooler sites, suggesting that microclimate preferences are species-specific. My results emphasize that high-resolution temperature data provide valuable insight into avian distribution dynamics in montane forest environments and that microclimate is an important variable in breeding season habitat selection by forest birds. I hypothesize that microclimate-associated distribution shifts may reflect species' potential for behavioral buffering from climate change in complex terrain. Factors influencing population trends often differ depending on the spatial scale under consideration. Further, accurate estimation of trends requires accounting for biases caused by imperfect detection. To test the degree to which population trends are consistent across scales, I estimated landscape-scale bird population trends from 1999-2012 for 38 species at the Hubbard Brook Experimental Forest (HBEF) in the White Mountains of New Hampshire, USA and compared them to regional and local trends (Chapter 4). I used a new method - open-population binomial mixture models - to test the hypothesis that imperfect detection in bird sampling has the potential to bias trend estimates. I also tested for generalities in species responses by predicting population trends as a function of life history and ecological traits. Landscape-scale trends were correlated with regional and local trends, but generally these correlations were weak (r = 0.12 - 0.4). Further, more species were declining at the regional scale compared to within the relatively undisturbed HBEF. Life history and ecological traits did not explain any of the variability in the HBEF trends. However, at the regional scale, species that occurred at higher elevations were more likely to be declining and species associated with older forests have increased. I hypothesize that these differences could be attributed to both elevated rates of land-use change in the broader region and the fact that the structure of regional data did not permit modeling of imperfect detection. Indeed, accounting for imperfect detection resulted in more accurate population trend estimates at the landscape scale; without accounting for detection we would have both missed trends and falsely identified trends where none existed. These results highlight two important cautions for trend analysis: 1) population trends estimated at fine spatial scales may not be extrapolated to broader scales and 2) accurate trends require accounting for imperfect detection.
Author: Pooja Panwar Publisher: ISBN: Category : Languages : en Pages : 112
Book Description
Agricultural expansion and increasing urbanization are driving rapid landscape modification in the Tallgrass prairies ecosystem and are affecting biodiversity at multiple spatial scales. Thus, the conservation of fragmented grassland and steeply declining grassland avifauna is dependent on the relationship between local- and landscape-scale factors and avian assemblage. We also need to understand how these factors, operating at different spatial scales, drive the occupancy of different guilds in the assemblage. We conducted repeated point count surveys during the breeding season of 2019 at 66 grassland sites across Arkansas and Missouri, USA. We developed a multi-species occupancy model to estimate species richness, and species- and guild-specific occupancy probability while accounting for species-specific detection probabilities. We examined the effect of landscape elements: type of landcover around a site, area and shape of a fragment and local-level elements: habitat type (remnant prairie/ hayfield), proximity to trees, and vegetation composition and structure on avian assemblage and guild-specific occupancy probability. Overall, we found that factors operating at landscape-scale have a significant effect on overall richness and composition of avian assemblage and guild-specific occupancy probability. The avian assemblage richness was higher for heterogenous landscape, small patches, and patches with more edge habitat which was a result of lower proportion of habitat specialists (grassland obligate) and higher proportion of habitat generalists. For grassland obligate species, high grassland cover, low forest cover, large patch area, less edge habitat, and lower litter depth had strong positive effects on their occupancy and guild-level species richness at a site. For grassland facultative species, high development around a site, small patch, high edge habitat, and lower litter depth had strong positive effects on their occupancy and guild-level species richness at a site. For woodland species, low grassland cover and high forest cover around a site, small patch, and high edge habitat had strong positive effects on their occupancy and guild-level species richness. Collectively, our results indicate that response to local- and landscape-scale factors varies between the guilds and habitat specialists are negatively affected by habitat fragmentation. Conservation efforts should focus on conserving landscapes, large tracts of prairies, minimize woody encroachment, reduce edge habitat and maintain heterogenous vegetation structure to mitigate grassland bird decline.
Author: Robert J. Fuller Publisher: Cambridge University Press ISBN: 1139851306 Category : Nature Languages : en Pages :
Book Description
The successful conservation of bird species relies upon our understanding of their habitat use and requirements. In the coming decades the importance of such knowledge will only grow as climate change, the development of new energy sources and the needs of a growing human population intensify the, already significant, pressure on the habitats that birds depend on. Drawing on valuable recent advances in our understanding of bird-habitat relationships, this book provides the first major review of avian habitat selection in over twenty years. It offers a synthesis of concepts, patterns and issues that will interest students, researchers and conservation practitioners. Spatial scales ranging from landscape to habitat patch are covered, and examples of responses to habitat change are examined. European landscapes are the main focus, but the book has far wider significance to similar habitats worldwide, with examples and relevant material also drawn from North America and Australia.
Author: Christopher Edward Latimer Publisher: ISBN: Category : Languages : en Pages : 169
Book Description
Changes to winter temperatures and variability of winter conditions are occurring at a faster rate than in other seasons. Over the past thirty years, researchers have documented poleward range shifts for many North American winter avifauna, but responses tend to be highly variable and idiosyncratic. Synergies between land-cover and regional climate can generate variable responses to climate change by altering species' exposure (e.g. creation of unique or altered microclimates) and/or sensitivity (e.g. physiological limits, behavior) to environmental change. My dissertation focuses on how landscape pattern interacts with weather to alter the relationships between exposure and sensitivity of wintering birds and their demographic consequences in human-modified landscapes. In Chapter 1, I used a network of temperature sensors to investigate the multi-scaled predictors of subcanopy microclimates (exposure) within a heterogeneous Midwestern landscape. Forests in fragmented landscapes further from urban centers experienced colder, more variable conditions that differed from gridded temperature estimates suggesting biophysical properties of landscapes should be considered when assessing species' vulnerabilities to future climate change. In Chapter 2, I measured the upper limit to heat production in a cold environment (MSUM) and used radiofrequency identification-enabled bird feeders to examine how MSUM influenced feeder use and survival of black-capped chickadees (Poecile atricapillus) across a forest fragmentation gradient. Birds with lower MSUM increased their use of feeders on colder days, and had lower apparent survival probabilities in highly fragmented forests. Chapter 3 examined whether microclimates and feeder use mediated the vulnerability of chickadees to extreme weather. Survivorship was higher during warmer periods, in more urban environments, and for birds with more frequent use of bird feeders throughout winter, but was unrelated to spatial microclimate heterogeneity. In Chapter 4, I used data from Project FeederWatch and dynamic occupancy models to examine how land cover moderates the effects of winter weather on population dynamics of resident bird species. Populations were more dynamic in more forested landscapes, presumably enabling them to better track resources. Together, these results suggest that habitat loss and fragmentation alter the relationships between environmental variability, behavior and physiology, and result in context-specific fitness consequences across landscapes.
Author: Andrew J. Dennhardt Publisher: ISBN: Category : Electronic dissertations Languages : en Pages : 301
Book Description
In this dissertation, I characterize the spatiotemporal dynamics of wild animal populations and communities via literature synthesis and three empirical studies. In Chapter 1, I review how historic foundations of macroecology and the theory of island biogeography inform ecology, restoration, and conservation across in the 21st Century. I conclude that restoration efforts should focus on evaluating and understanding the historical and recent ecological context of areas targeted for restoration, particularly on multiple spatiotemporal scales.In Chapter 2, I investigate historic dynamics of freshwater fish populations and communities inhabiting Ontario, CAN jurisdictional waters of Lake Huron. I apply a multivariate hierarchical model to relative counts of multiple fish species to estimate fine- and broad-scale effects of environmental and anthropogenic factors associated with species dynamics over time. I conclude that conservation efforts should focus on ecosystem-level governance of Lake Huron fisheries, including expanded ectoparasite control as well as enhanced structural-climatic conditions to maintain stationary water temperatures and nutrient cycling over time.In Chapter 3, I evaluate historic dynamics of grassland bird populations and communities inhabiting Conservation Reserve Enhancement Program (CREP) lands in eastern Michigan, USA. I apply a multivariate hierarchical model to relative detections and non-detections of multiple species to estimate fine- and broad-scale effects of environmental and anthropogenic factors associated with species occupancy dynamics over time. I conclude that conservation efforts should focus on increasing the area, frequency, diversity, and distribution of CREP planting practices as well as implement new studies over numerous locations and for extended time periods throughout the Upper Midwest and Great Plains of North America to help ensure the persistence of remnant grasslands and their rarest bird species.In Chapter 4, I assess how mass-scaling (allometric) relationships can be used to estimate the abundance of wild bird populations across continental North America. I apply a univariate hierarchical model to relative counts of a common forest bird to estimate fine- and broad-scale effects of environmental and anthropogenic factors associated with species dynamics over time. I conclude that conservation should focus on expanding the spatiotemporal coverage of banding sites for measuring species body-size characteristics as well as require multiple (geolocated) site visits (e.g., 9́Æ 3 times per season) in broad-scale monitoring programs, particularly such that allometric-scaling relationships may be better evaluated with hierarchical models investigating indices of species abundance and occupancy status.I conclude this dissertation with a discussion of the major findings, lessons learned, and implications and recommendations for future population and community research in ecology. Future studies that critically investigate ecological phenomena at various scales, including explicit accounts for ecological data hierarchies, will likely be most useful for separating statistical signal from noise and identifying the scales at which phenomena manifest. Such research will improve basic theory as well as help facilitate improved conservation of biodiversity via increasingly more certain descriptions of ecological patterns and processes, including the scales at which each can be influenced or managed.
Author: Christina Galitsky Publisher: ISBN: Category : Biodiversity Languages : en Pages : 58
Book Description
Both fine scale patterns of vegetation and coarser scale landscape patterns affect bird community composition and structure. However, the relative importance of the drivers at these two spatial scales continues to be debated. Here, we show how the factors that drive avian diversity and community structure depend on context, including the particular environment studied, the response variables analyzed, and the groups of species examined. We explored the relative roles of landscape pattern and stand structure and composition in defining bird communities in 44 remnant oak stands in the Willamette Valley, Oregon. We focused on two key questions--are bird communities influenced more by landscape patterns (at the matrix and patch levels) or stand composition and structure, and in what contexts are each of these spatial scales more important. We conducted point counts to determine avian abundance, richness, and evenness and categorized birds into functional groups based on diet and foraging tactics. We then used canonical correspondence analysis and generalized linear models to analyze overall community patterns, functional group diversity, synanthropic and non-synanthropic species diversity, and the abundance of individual species of concern. Both local and landscape factors significantly influenced each group of avian species for every measure of diversity we tested, but their relative importance varied markedly. Local factors explained four times more variance than landscape factors for overall species diversity and double the variance for two functional groups. For the other functional groups, landscape factors were up to ten times more important. We found the same high variability for individual species, depending on the species evaluated. When we evaluated factors more specifically at the landscape level, we found that the surrounding matrix was much more important than patch variables for each group of birds we tested. However, we also found that patch size influenced some groups and individual species much more than others, and some not at all. Understanding the degree to which species respond to local environmental conditions and landscape patterns is an essential part of optimizing scarce conservation resources and our results indicate that such an understanding will need to be put into very specific context.
Author: Laszlo Erdos Publisher: MDPI ISBN: 3036506705 Category : Science Languages : en Pages : 170
Book Description
Forest-steppes occupy a wide zone between Eurasian closed canopy forests and open steppes and feature a mosaic of woody and herbaceous vegetation. Due to the occurrence of structurally, compositionally, and environmentally strongly different habitats in close proximity, high spatial heterogeneity is one of the key characteristics of forest-steppe ecosystems. This volume presents ten contributions examining forest-steppe heterogeneity and its effects on environmental factors, plant communities, and animals.
Author: Sarah Jean Kiuama Frey
Author: Sarah Jean Kiuama Frey
Author: Pooja Panwar
Author: Robert J. Fuller
Author: William Bernard Kristan (III.)
Author: Christopher Edward Latimer
Author: Andrew J. Dennhardt
Author: John Francis McLaughlin
Author: 
Author: Christina Galitsky
Author: Laszlo Erdos