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Predicting Impacts Of Future Human Population Growth And Development On Occupancy Rates And Landscape Carrying Capacity Of Forest Dependent Birds
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Book Synopsis Predicting Impacts of Future Human Population Growth and Development on Occupancy Rates and Landscape Carrying Capacity of Forest-dependent Birds by : Michelle Lynn Brown
Download or read book Predicting Impacts of Future Human Population Growth and Development on Occupancy Rates and Landscape Carrying Capacity of Forest-dependent Birds written by Michelle Lynn Brown and published by . This book was released on 2012 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: However, 30% of the towns in the study area were projected to add less than 1 housing unit per ha. In the face of this predicted human growth, the overall occupancy of each species decreased by as much as 38% in certain places in the study area in the year 2050. These declines were greater outside of protected areas than within protected lands. Nk was predicted to decrease 44% in the landscape classified as exurban development, 25% in urban and suburban development, and 14% in rural development. These decreases far exceeded the decreases in occupancy probabilities that ranged between 3% and 5% across the same sampled sites. This spatial approach to wildlife planning provides data to evaluate trade-offs between development scenarios and the viability of forest-dependent wildlife species. Specifically, maximum clique analysis is a tool that can be used to estimate a species population metric, Nk, and provide decision-makers with straightforward data to inform decisions and communicate with stakeholders.
Book Synopsis Effects of Spatial Scale and Heterogeneity on Avian Occupancy Dynamics and Population Trends in Forested Mountain Landscapes by : Sarah Jean Kiuama Frey
Download or read book Effects of Spatial Scale and Heterogeneity on Avian Occupancy Dynamics and Population Trends in Forested Mountain Landscapes written by Sarah Jean Kiuama Frey and published by . This book was released on 2014 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Habitat Capability Model for Birds Wintering in the Black Hills, South Dakota by : Mark A. Rumble
Download or read book Habitat Capability Model for Birds Wintering in the Black Hills, South Dakota written by Mark A. Rumble and published by . This book was released on 1999 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Habitat models have considerable economic effects on management decisions and are used to predict consequences of land management decisions on wildlife. The Black Hills National Forest uses the habitat capability model (HABCAP), but its accuracy relative to resident wintering bird populations is largely unknown. We tested the model's predictive accuracy for resident nongame birds wintering in 11 vegetation structural stages of ponderosa pine, quaking aspen/paper birch, and meadows in the Black Hills, South Dakota. Six species, hairy woodpecker, gray jay, black-capped chickadee, white-breasted nuthatch, red-breasted nuthatch, and dark-eyed junco, had HABCAP coefficients for vegetation structural stages during winter. Red crossbills were not previously included in the model, so we developed HABCAP coefficients for them. Predicted abundance of winter birds in vegetation structural stages based on HABCAP coefficients differed from observed abundance for gray jays, black-capped chickadees, white-breasted nuthatches, red-breasted nuthatches, and dark-eyed juncos. HABCAP coefficients were modified to reflect observed abundance patterns of birds. These changes to HABCAP coefficients should provide managers with more appropriate estimates of land management impacts on nongame birds wintering in the Black Hills.
Book Synopsis Ecological Responses of Avian Species to Land Cover Metrics at the Landscape-Level and Across Broad Spatial Extent by : Rafael Xavier De Camargo
Download or read book Ecological Responses of Avian Species to Land Cover Metrics at the Landscape-Level and Across Broad Spatial Extent written by Rafael Xavier De Camargo and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Human activities have transformed natural landscapes into human-dominated areas at unprecedented rates in the last centuries. Land cover transformation is associated with loss of natural habitat, thus a threat to biodiversity. Because habitat loss will likely continue in the future due to population growth and increase demand for natural resources, an important question in ecological studies is whether land cover features (i.e. amount, variety, shape, configuration) can be used as predictors to estimate species loss from habitat modification. This thesis investigates the predictive ability of landscape features in predicting species distributions at the landscape level and across large regions. It tests several predictions from classic hypotheses such as the species-area relationship and habitat fragmentation, utilizing a macroecological approach. Response variables (e.g. species richness, species' probability of occurrence) and independent variables (e.g. proportion of natural areas, metrics of fragmentation, temperature, etc.) are analysed in cell sizes of 25-900km2 covering large regions (e.g. southern Ontario, New York State). Bird species were chosen as the main biological model. Most literature assumes that species richness should vary positively as a function of remaining natural area, following the well-known species-area relationship (i.e. classic SAR). Prior studies have shown that avian species richness has a peaked, rather than a monotonic increasing, relationship with the proportion of natural land cover in landscapes of southern Ontario. The first chapter of the thesis showed improvements in the predictive power of classic SARs by proposing the "Lost-habitat SAR", which demonstrates that richness of open-habitat species can be predicted when we partition human-dominated land cover into an ''available human-dominated'' component and ''lost'' habitat (i.e. parts of the landscape that can no longer be utilized by any species). The second chapter addresses a current contention in the literature about the effect of habitat fragmentation beyond habitat amount at the landscape level. Specifically, I tested the effect of fragmentation (e.g. number of patches) on both avian richness and the probability of occurrence (pocc) of individual species, after controlling for habitat amount in 991 landscapes, each 100-km2, in southern Ontario. The analysis showed that overall species richness responds primarily to habitat amount, and that the effect of habitat fragmentation, holding the total amount of habitat constant, is negligible. The probability of occurrence of a few bird species did relate negatively to the size, number and isolation of the patches within the landscape. We argue that the evidence is inconsistent with the hypothesis that reducing habitat fragmentation would be an effective conservation strategy for birds at the landscape level. Chapter 3 tested the speculation in the climate change literature that habitat loss may impede the colonization or movement of species whose ranges are shifting northwards in response to climate. Using the same 100-km2 landscapes of southern Ontario, I examined individual bird species' probability of occupancy as a function of the amount of remaining natural land cover for three groups of species: i) those whose northern range limit falls within the study area, ii) those whose southern range limit is in the study area, and iii) those whose ranges cover the entire study area. The results showed that the probability of occupancy of southern-edge species is a positive function of the amount of natural land cover (forest) in the landscape, while the probability of occupancy of northern-edge species is a negative function of natural land cover. Hence, I conclude that at southern range limits species faces the dual stresses of climatic warming and habitat conversion. Whereas, at northern (potentially expanding) range edges, partially disturbed landscapes are more readily occupied than undisturbed landscapes. In the final chapter, I challenge widely accepted hypothesis that habitat loss causes biodiversity loss by testing whether conserving natural land cover would conserve species diversity. More specifically, I tested whether broad-extent relationships between avian species richness and natural land cover are independent of: 1) whether species distribution data come from systematic censuses (atlases) versus range maps, and 2) the grain size of the analysis in grid cells covering southern Ontario, CA, and New York State, US. My findings showed that over regional extents, range-map-based richness relates strongly to temperature, irrespective of spatial grain, and that censused species richness relates to temperature less strongly. Moreover, range-map richness is a negative function of the proportion of natural land cover, while realized richness is a peaked function. Therefore, I conclude that conserving natural land cover would not conserve species diversity in southern Ontario or in New York State, since greater natural cover does not imply higher richness. We argue that habitat loss has become a panchreston. It may be misguiding conservation biology strategies by focusing on a threat that is too general to be usefully predictive.
Book Synopsis Effects of Climate Change on Birds by : Anders Pape Møller
Download or read book Effects of Climate Change on Birds written by Anders Pape Møller and published by Oxford University Press, USA. This book was released on 2010-08-12 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Effects of Climate Change on Birds provides an exhaustive and up-to-date synthesis of the science of climate change as it relates to birds." -- Back cover.
Book Synopsis A Landscape-scale Assessment of the Response of Birds to Land Cover, Climate, and Forest Management by : Jaymi J. LeBrun
Download or read book A Landscape-scale Assessment of the Response of Birds to Land Cover, Climate, and Forest Management written by Jaymi J. LeBrun and published by . This book was released on 2015 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change has the potential to significantly increase temperatures across the globe as well as alter regional climates. Within the central United States, projections call for warm, wet winters and hot, dry summers. These climate shifts in the Midwest to more southerly conditions have the potential to substantially change vegetation and reshape both plant and animal distributions. To mitigate these potential changes, scientists have suggested management strategies focused on forest resilience, response or adaptation to change, and carbon sequestration. My objectives were to: 1) determine the current impacts of land cover and regional climate conditions on five focal bird species in the Midwestern United States, and 2) use these current relationships to assess the direct and indirect effects of future climate and management on the relative abundance of these five bird species (i.e., prairie warbler, blue-winged warbler, northern bobwhite, pine warbler, and worm-eating warbler) within the Ozark Highlands of southern Missouri. I used a Bayesian hierarchical framework to estimate current abundance across a latitudinal gradient. I then coupled the Bayesian hierarchical model with a landscape simulation model (LANDIS PRO) to predict relative abundance 100 years into the future. I used landscape simulation models developed for a range of future climates (current climate conditions, PCM-B1, GFDL-A1fi, and Hadley-A1fi) under several forest management strategies designed to mitigate climate change (response/adaptation, resilience, and carbon sequestration) to make my avian abundance predictions. I found forest and canopy cover were the primary drivers of current species abundance, however, temperature was influential for early successional species. In addition, the most significant climate related effect was for the northern bobwhite with higher abundances under warmer winters. In the next 100 years, I predict land cover to change very little due to climate; however, management should change land cover with the most significant changes occurring for coniferous forest and contagion. I found, for most species, management has a greater impact on future avian abundance than climate, however, species currently exhibiting direct effects of climate showed compounded effects associated with management. Only one species exhibited any indirect effects associated with climate (i.e., northern bobwhite), and increased mean abundance by 10% under current management and the Hadley GCM, coinciding with a 2% decrease in contagion. In addition, I predict prairie warblers to decrease in abundance once temperatures reach 36°C by the end of the century. Birds experience species-specific response to both land cover and climate. It is important to be cognizant of the type of changes predicted to occur across the landscape as well as the actual drivers of abundance. Management activities focused on increasing forest cover will play an important role in mitigating effects of future climate by providing habitat refugia to species vulnerable to projected changes while maximizing carbon sequestration.
Book Synopsis Consequences of habitat loss and change to populations of wintering migratory birds by : J. Goss-Custard
Download or read book Consequences of habitat loss and change to populations of wintering migratory birds written by J. Goss-Custard and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Population models show that the response of migratory bird populations to a reduction in the area, or change in the quality, of their winter feeding areas depends critically on the shape (linear or non-linear) and strength (slope) of the relationship describing how the proportion dying from starvation changes with population density, Yet the parameters that define such density- dependent functions are extremely difficult to estimate from direct measurements of mortality at different population sizes. Even if they could be estimated, there would be uncertainty as to whether or not the relationship would remain the same, and thus provide reliable predictions, in the new circumstances for which forecasts are required. This paper summarizes studies of the Oystercatcher Haematopus ostralegus which aim to derive the shape and strength of the winter density-dependent mortality and emigration function for one estuary, under existing and new circumstances, from the responses of individual birds to each other and to their spatially and seasonally varying food supply. Based on these studies, an individuals-based, physiologically structured game theoretic distribution model has been built which predicts the carrying capacity and numbers of birds dying at different population sizes. The model also can be applied to Oyster-catchers occupying several estuaries distributed throughout their wintering range and can thus be extended to the entire biogeographical or global population, In addition, it can be used to identify some easily measured behavioural and ecological parameters that identify those species, from a wide range of taxa, that are most likely to be affected by habitat loss and change.
Book Synopsis A Temporally Explicit Investigation of the Effects of Habitat Change on Landbird Population and Community Dynamics by : Elizabeth Laura Porzig
Download or read book A Temporally Explicit Investigation of the Effects of Habitat Change on Landbird Population and Community Dynamics written by Elizabeth Laura Porzig and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Studying population and community dynamics through time provides a better understanding of the ecological impacts of increasing rates of anthropogenic change. Such investigations can (1) validate the tools we use to understand and predict the impacts of environmental dynamics, (2) identify dominant processes affecting populations and communities, and (3) provide insight into the mechanisms of population response to environmental change. Here, I use long-term data from the Palomarin Field Station in coastal California detailing three decades of landbird population and community dynamics at a site undergoing secondary plant succession to better understand the effects of environmental change on landbirds. In Chapter 1, I compare the ability of a habitat suitability models (HSMs) to logistic population models to explain and predict trends in abundance of seven species. HSMs are increasingly used to predict species response to future climate and land-use scenarios. However, these models do not explicitly incorporate time-dependent processes such as population growth rates and the strength of density dependence. I compared HSMs to logistic population models in explaining and predicting landbird response to vegetation change at Palomarin. In the retrospective comparison, I found that HSMs performed well in explaining variation in trends of the seven species over a 23-year period from 1983-2005, explaining between 58 and 90% of deviance. However, for three of the species, Song Sparrow (Melospiza melodia), White-crowned Sparrow (Zonotrichia leucophrys), and Wrentit (Chamaea fasciata), a logistic population model provided a better fit to the retrospective data. These three species have more localized dispersal, suggesting that incorporating population processes into habitat suitability modeling for species with similar dispersal patterns may improve projections. In the prospective evaluation, I used both model types to predict changes in abundance from 2006-2010, and I compared these predicted abundances to the observed abundances. Neither model type performed consistently better in predicting species trends over the five year period. In summary, I found that overall HSMs can explain and predict species' trends through time; however, for species with localized dispersal, incorporating population processes may improve understanding. There is strong evidence that differential response of species to changes in the environment will result in novel community assemblages. An unresolved question is the degree to which interspecific interactions influence long-term changes in populations, since most analyses have considered species responses to occur independently of the community in which they occur. In the Chapter 2, I applied a hierarchical approach and Bayesian inference to the times series of seven species used in my first chapter to partition variance in species trends between interspecific interactions, intraspecific processes and environmental forcing. I found that within-guild interspecific interactions were the least important contributor to variation in species trends, explaining between 0 and 5% of variation. Vegetation and rainfall variation, combined, explained 6 to 30% of variation in species trends. Intraspecific processes explained between 0 and 39% of variation. Between 27 to 90% of variation was attributed to unexplained variation. While these are not novel species interactions, as would be expected in communities resulting from anthropogenic change, these results suggest that within-guild interactions are not a major source of variation in landbird population trends. In the third chapter of my dissertation, I investigated the underlying behavioral and demographic mechanisms of species' response to environmental dynamics. I focus on one species, White-crowned Sparrow, which has declined dramatically in density since 1980. I evaluate patterns in vegetation change, nest site selection, and three measures of reproductive success to understand the effect of habitat change on individuals and to provide insight into the degree to which White-crowned Sparrows are able to ameliorate the effects of habitat change through behavioral decisions. I found that White-crowned Sparrows prefer early successional habitat, and no evidence for an effect of the range of experienced habitat conditions on variation in nest survival, clutch size, or number of fledglings. These results provide evidence that through their strong habitat preference, individual White-crowned Sparrows are able to narrow the range of successional habitat they experience, and thus do not incur a demographic cost of habitat change on reproductive success. These results demonstrate the species' ability to adjust to habitat change through behavioral decisions. As we recognize the degree to which anthropogenic forcing creates environmental change, we are increasingly aware that the impact of these changes will depend in part upon the rate at which they occur. By explicitly studying landbird population and community response to three decades of habitat change, this dissertation provides insight into the ecological processes that influence variation in population abundances, the mechanisms underlying species' response to environmental change, and the efficacy of the tools we use to study and predict these responses. My findings that (1) HSMs perform well in explaining variation in species trends through time, (2) interspecific interactions are not a dominant driver of trends, and (3) habitat selection decisions can ameliorate the negative effects of habitat change on reproductive success provide a baseline of understanding to which we can compare changes in other systems and at other time scales in order to better understand and explain ecological change in a time of increasing rates of change and increasing variability.
Book Synopsis Effects of Habitat Characteristics on Occupancy and Productivity of a Forest-Dependent Songbird in an Urban Landscape by : Dianne Hali Robinson
Download or read book Effects of Habitat Characteristics on Occupancy and Productivity of a Forest-Dependent Songbird in an Urban Landscape written by Dianne Hali Robinson and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Habitat fragmentation and isolation can result in decreased occupancy and reproductive success within songbirds, particularly for species inhabiting urban environments where suitable habitat may be limited. The golden-cheeked warbler (Setophaga chrysoparia) is a federally endangered songbird that inhabits oak-juniper (Quercus spp.- Juniperus spp.) across central Texas. Past research on this warbler has indicated decreased patch occupancy near urban areas and negative reproductive effects associated with decreased distance to edge and decreased canopy cover. A rural study indicated warblers occupy patches [greater than or equal to]3 ha, and warblers in patches [greater than or equal to]20 ha are more likely to successfully fledge young. There are no thresholds yet identified for this warbler within urban environments, where effects of habitat fragmentation on reproductive success are more pronounced than within rural environments. I monitored patch occupancy, territory establishment, pairing success, and fledging success of warblers in an urban environment. I determined minimum patch-size thresholds for productivity measurements, and also monitored effects on productivity from canopy cover, woodland composition, distance to and size of the nearest habitat patch, and distance to the nearest habitat patch >100 ha. I compared my results to those from a similar study conducted in a rural system. I compared territory size and territory density between an urban and rural system. Warblers occupied 24% (n = 63) patches surveyed; the smallest patch occupied was 3.5 ha. The smallest patch with an established territory was 10.7 ha, and 10% (n = 63) of habitat patches had at least one established territory. Warblers successfully fledged young in 3 patches, the smallest of which was 26.5 ha. I found patch-size was predictive for territory establishment and pairing success with warblers requiring 13 ha (95% CI: 10.0 - 16.8 ha) and 19 ha (95% CI: 15.7 - 22.6 ha) habitat patches, respectively. I found a minimum threshold of approximately 66% canopy cover (95% CI: 65.2 - 66.4%) required for patch occupancy, and found no warblers established a territory in a habitat patch >25 m from the next nearest patch. I found higher minimum thresholds within an urban system for territory establishment and pairing success than those seen within a rural system. I suggest preserving warbler habitat patches >22 ha that are in close proximity to other habitat patches. This will help to enhance warbler habitat within urban areas and maintain reproductively viable habitat patches, while not halting development completely. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149511
Download or read book Our Common Future written by and published by . This book was released on 1990 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Environmental Impacts of Wind-Energy Projects by : National Research Council
Download or read book Environmental Impacts of Wind-Energy Projects written by National Research Council and published by National Academies Press. This book was released on 2007-09-27 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: The generation of electricity by wind energy has the potential to reduce environmental impacts caused by the use of fossil fuels. Although the use of wind energy to generate electricity is increasing rapidly in the United States, government guidance to help communities and developers evaluate and plan proposed wind-energy projects is lacking. Environmental Impacts of Wind-Energy Projects offers an analysis of the environmental benefits and drawbacks of wind energy, along with an evaluation guide to aid decision-making about projects. It includes a case study of the mid-Atlantic highlands, a mountainous area that spans parts of West Virginia, Virginia, Maryland, and Pennsylvania. This book will inform policy makers at the federal, state, and local levels.
Download or read book Forests on the Edge written by and published by . This book was released on 2005 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The private working land base of America's forests is being converted to developed uses, with implications for the condition and management of affected private forests and the watersheds in which they occur. The Forests on the Edge project seeks to improve understanding of the processes and thresholds associated with increases in housing density in private forests and likely effects on the contributions of those forests to timber, wildlife, and water resources. This report, the first in a series, displays and describes housing density projections on private forests, by watershed, across the conterminous United States. An interdisciplinary team used geographic information system (GIS) techniques to identify fourth-level watersheds containing private forests that are projected to experience increased housing density by 2030. Results indicate that some 44.2 million acres (over 11 percent) of private forests--particularly in the East, where most private forests occur--are likely to see dramatic increases in housing development in the next three decades, with consequent impacts on ecological, economic, and social services. Although conversion of forest land to other uses over time is inevitable, local jurisdictions and states can target efforts to prevent or reduce conversion of the most valuable forest lands to keep private working forests resilient and productive.
Download or read book Popular Science written by and published by . This book was released on 2007-08 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Popular Science gives our readers the information and tools to improve their technology and their world. The core belief that Popular Science and our readers share: The future is going to be better, and science and technology are the driving forces that will help make it better.
Book Synopsis INFLUENCES OF A HUMAN-DOMINATED LANDSCAPE ON MIDWESTERN BREEDING BIRD OCCUPANCY AND DIVERSITY by : Bryce T. Adams
Download or read book INFLUENCES OF A HUMAN-DOMINATED LANDSCAPE ON MIDWESTERN BREEDING BIRD OCCUPANCY AND DIVERSITY written by Bryce T. Adams and published by . This book was released on 2014 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Human land use dominates the globe, and ecologists and developers are challenged to incorporate effective conservation strategies into human-dominated landscapes that maximize biodiversity and minimize impacts to growth and production. I sought to contribute to general ecological theory by examining the effects of human-dominated landscapes on diversity and distribution patterns of midwestern breeding birds in the Oak Openings Region of northwestern Ohio from 23 May to 2 July 2013 and from 230 point count locations. To better understand the relative importance of matrix, habitat, and localized development, I modeled occurrences of 18 species of birds using an occupancy modeling framework, and occurrences of 10 of those 18 species were best explained by matrix quality over habitat loss and fragmentation. I investigated the importance of habitat structural diversity on diversity patterns of 3 guilds: Neotropical, Nearctic, and exotic species. My diversity models indicated that Neotropical diversity was best explained by habitat amount and secondarily by habitat structural diversity, while the Nearctic guild was best explained by habitat isolation and secondarily to habitat structural diversity. For a subset of survey locations distributed in the urban center, occurrences of native species were best explained by localized habitat amount and habitat structural diversity and not by the proximity to large natural reserves in the area. Finally, I used advances in distribution modeling techniques to predict the spatial distribution of Red-bellied Woodpecker (Melanerpes carolinus). My models predicted that habitat isolation and habitat amount were important determinants of occupancy for this species. My work suggests that midwestern breeding bird conservation should focus on conserving matrix quality, restoration of globally unique habitat types, and the addition of localized habitat features in the urban center.
Book Synopsis Bird-vegetation Relationships Across Ten Years After Thinning in Young Thinned and Unthinned Douglas-fir Forests by : Svetlana Yegorova
Download or read book Bird-vegetation Relationships Across Ten Years After Thinning in Young Thinned and Unthinned Douglas-fir Forests written by Svetlana Yegorova and published by . This book was released on 2012 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bird-vegetation associations are a base for bird conservation and management, as well as for predictions of the effects of resource management and climate change on wildlife populations. A recent shift in forest management priorities from timber production to native species' habitat conservation on federal lands has emphasized the need to understand the mechanisms underlying the effects of vegetation management on wildlife. The assumption of strong bird-vegetation relationships is rarely tested for forest birds, especially at large temporal extents, which are more likely to reveal instabilities in bird-vegetation relationships than short-term studies. This study aimed to quantify bird-vegetation relationships and investigate their strength in young thinned and unthinned Douglas-fir forest stands over ten to years post thinning. Additionally, this study investigated whether disturbance associated with forest thinning decoupled bird-vegetation relationships in the thinned and unthinned stands. I used abundance or occurrence data for eight bird species collected at 58 point count surveys, conducted during six breeding seasons over ten years following forest thinning. I obtained detailed local-scale vegetation characteristics associated with bird sampling points and modeled bird occurrence or abundance as a function of vegetation characteristics. Vegetation characteristics explaining individual species occurrence or abundance varied among species and among years for any given species. Six out of eight species showed responses to examined vegetation characteristics. For three out of six species, the effects of vegetation characteristics on bird occurrence or abundance remained consistently positive or negative over time. For the other three species the absolute effect of vegetation decreased over time to that of not statistically different from zero. The estimates of vegetation effects on bird response varied in size among years, though they were not statistically different among years. Magnitude of vegetation effect on bird occurrence or abundance did not increase with time, nor was it related to species prevalence or abundance. I found evidence of a response threshold for one species, Swainson's thrush. I suggest that changing abundance of resources, associated with thinning disturbance, demographic stochasticity associated with small population sizes, as well as large-scale demographic processes and possibly life history traits of examined species, mediate the strength of local-level bird-vegetation associations. Variability of vegetation effects on bird occurrence or abundance over time suggests a greater uncertainty of results of vegetation-related wildlife management efforts than has previously been suggested by short-term studies. Therefore, incorporation of the uncertainty of bird-vegetation relationships into predictive models and continued long-term monitoring of species response to management may be crucial for future successful and effective management decisions.
Book Synopsis Life in a Changing World by : Nina Margaret McLean
Download or read book Life in a Changing World written by Nina Margaret McLean and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anthropogenic climate change is predicted to be a major cause of extinctions. Therefore, a major aim of climate change ecology is to understand how species are being impacted and identify which species are most at risk. However, the ability to make these broad generalisations requires large-scale comparative analyses based on appropriate assumptions. This thesis investigates how European birds respond to changes in climate, the validity of several common assumptions, and identifies which species or populations are most at risk based on multiple long-term datasets. Our understanding of how different responses relate and how they affect population persistence is lacking. A conceptual hierarchical framework is introduced in chapter one to better understand and predict when climate-induced trait changes (phenology or physiology) impact demographic rates (survival or reproduction), and subsequently population dynamics. I synthesise the literature to find hypotheses about life-history and ecological characteristics that could predict when population dynamics will likely be affected. An example shows that, although earlier laying with warmer temperatures was associated with improved reproduction, this had no apparent effect on population trends in 35 British birds. Number of broods partly explains which species are most at risk of temperature-induced population declines. It is often assumed that populations within species respond similarly to climate change, and therefore a single value will reflect species-specific responses. Chapter two explores inter- and intra-specific variation in body condition responses to six climatic variables in 46 species over 21 years and 80 sites. Body condition is sensitive to all six variables (primarily in a non-linear way), and declines with warmer temperatures. I find that species signals might not exist as populations of the same species are no more alike than populations of different species. Decreased body condition is typically assumed to have detrimental consequences on species' vital rates and population dynamics, but this assumption has rarely been tested. Expanding on chapter two, chapter three shows that temperature-induced declines in body condition have no apparent consequences on demography and population dynamics. Instead, temperature has strong effects on reproductive success and population growth rates via unknown traits and demographic rates. Much of the literature investigating climatic impacts assumes that temporal trends accurately reflect responses to climate change, and therefore investigate trait changes over time. In chapter four, I use two long-term datasets to demonstrate that, for four different types of trait responses, trait variation through time cannot be assumed to be due to warming. Non-temperature causal agents are important in explaining temporal trends, often resulting in reinforced effects. Consequently, the roles of climatic and non-climatic effects need to be understood to better predict those species most at risk. This thesis lays the foundations for more holistic climate change research that encompasses relationships among multiple response types, species and populations. Such knowledge will be vital for future conservation efforts.
Book Synopsis Genetic and Demographic Consequences of Human-driven Landscape Changes on Bird Populations by : Cintia Cornelius
Download or read book Genetic and Demographic Consequences of Human-driven Landscape Changes on Bird Populations written by Cintia Cornelius and published by . This book was released on 2006 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Human activities, such as agriculture and forest exploitation, have modified landscapes worldwide. Despite a large accumulation of empirical and theoretical knowledge on habitat loss and fragmentation, some aspects remain poorly understood, especially those related to interactions between different forms of habitat degradation. The overall goal of this research was to study the effects of forest fragmentation and changes in forest structure on bird populations in a human-modified landscape in the temperate rainforest of South America using Aphrastura spinicauda (Furnariidae) as a model species. I evaluated i) if replacement of forest by open habitat leads to reduced dispersal influencing the genetic structure of populations; ii) if density and reproductive success vary across a fragmented landscape and if populations are limited because of nest-site availability in forests that differed in structure (modified by selective logging) and degree of isolation; and iii) if nest-site selection and associated consequences on fitness are spatially variable in response to changes in forest structure and connectivity. First I show that forest replacement by open habitat reduced landscape connectivity and influenced the genetic structure of populations even within the time-space scale of human-caused fragmentation. Secondly, I show that bird density varied across the fragmented landscape while nesting success remained constant. Aphrastura spinicauda is a non-excavator cavity-nester and thus relies on old trees or snags where cavities form. A nest-site supplementation experiment revealed that nest-site limitation is the primary cause of density reduction in selectively-logged forests, but that other processes related to forest fragmentation (e.g. loss of connectivity) also influence population responses to habitat changes. Finally, I showed evidence for adaptive nest-site preferences, but also that nest-site choice is spatially variable in response to ecological gradients produced by human activities. By combining genetic and demographic responses of populations I provided evidence for unforeseen and potentially synergistic interactions among different forms of habitat degradation. These results emphasize the need of explicit and independent consideration of habitat fragmentation and other forms of habitat degradation, when studying populations in human-modified landscapes. In that way, we can better understand and predict population persistence and their adaptive responses in these landscapes.
