1,720,956 research outputs found
Plant Community Development in Storm-induced Overwash Fans of the Otis Pike Fire Island High Dune Wilderness Area, New York
Get PDFBarrier island systems are driven by disturbance, climate, and geomorphology. Previously, barrier island vegetation communities were primarily described by microclimate variability. The purpose of this dissertation is to better understand effects of white-tailed deer on developing plant communities on barrier islands after a catastrophic disturbance. I used distance-based Moran\u27s eigenvector maps to identify spatial structures in vegetation communities of overwash fans in the third and fourth years after Hurricane Sandy. Spatial structures were present and significant at two or more frequencies in all overwash fans and explained the greatest amount of variation in vegetation community composition. Induced spatial dependence was predominantly controlled by proximity to foredune. I identified five biotic and abiotic influences to community composition in overwash fans and ranked their importance through canonical correspondence analysis. Gradients in productivity and elevation were primarily responsible for community composition and deer effects were not identifiable at the plot level. I identified effects of deer on vegetation cover and richness through a paired exclosure experiment, though only cover effects were statistically significant. Deer effects on cover were starker than those observed on species richness, suggesting assessments of deer effects on depauperate communities should focus on richness and cover. Lastly, I assessed effects of white-tailed deer on the rate of vegetation recovery in overwash fans through imagery classification and assessments of local white-tailed deer density. Though deer affect vegetation cover through trampling, grazing, and browsing in overwash fans, their effects on recovery rates were minimal and not statistically significant. Two overwash fans are expected to recover to pre-Sandy conditions within the decade since a nascent foredune is present and growing. Two overwash fans may never recover due to continued disturbance. The five remaining overwash fans have a slowly-forming nascent foredune, and changes in climate and frequency of storm events make their futures uncertain. Though deer do not pose a threat to the resilience of the barrier island, selective foraging behaviors may change composition and developmental trajectories of recovering vegetation communities over time
Effects of landscape composition and structure on abundance and distribution of urban white-tailed deer
Get PDFExpanding urban white-tailed deer populations are causing concerns for wildlife professionals and residents. I used distance sampling to estimate deer population density and abundance in the eastside communities of Syracuse, New York. I estimated a population size of between 93 - 159 deer (mean: 121) for 28.9 square kilometers of the study area. I classified high resolution orthoimagery and identified patches of cover with deer behavior thresholds and an animal-centric delineation algorithm. I predicted deer abundance from binomial mixture models and a suite of landscape covariates. Model weight of evidence supported variables corresponding to cover, food, and water constituents on the landscape. Deer population density predicted from abundance modeling was 73% higher than the distance sampling estimate indicating a substantial bias. Because assumptions associated with distance sampling and mixture modeling were reasonably met, low encounter rates with deer during sunrise surveys are the probable cause of the observed discrepancy
Data Collected for Report Entitled ''Evaluating Legacy Effects of Hyperabundant White-Tailed Deer in Forested Stands of Harriman and Bear Mountain State Parks, New York
No full textWhite-tailed deer (Odocoileus virginianus) are among the most impactful herbivores in the eastern United States. The lower Hudson Valley in New York has been heavily browsed by white-tailed deer since the early 20th century and the region has some of the lowest tree regeneration rates in New York State as a result of deer browsing and subsequent increases in interfering vegetation. The U.S. Geological Survey and the State University of New York studied sites where deer hunting is permitted (case sites) and nearby sites where hunting is currently prohibited (control sites) to assess and identify forest structure and composition differences. We used a case-control study and inferred recovery by comparing vegetation characteristics on adjacent sites in the lower Hudson Valley with similar forest communities and land uses but different deer population management histories. We surveyed more than 200 plots in upland forest types across case and control sites where we assessed forest condition by estimating density (number per unit area) and composition and cover (percent) of important vegetation constituents in ground, shrub, subcanopy, and canopy layers of the forest. We recorded 37 tree species, 22 shrub species, 57 herbaceous species, and 19 species of grasses and sedges in our plot surveys, including a number of nonnative and invasive plants. We also estimated the ages of a number of common canopy trees by counting rings from cores extracted from individual stems. Effects of more than 100 years of chronic deer browsing manifested in low herbaceous ground cover and little to no tree recruitment (saplings) on lands without deer management. In contrast, sustained deer management resulted in forests with conditions that indicated substantial recovery from chronic herbivory in the ground, shrub, and subcanopy layers. Sites with ongoing deer management exhibited greater ground cover of tree seedlings and herbs and less ground cover of interfering vegetation and nonnative species. The well-developed subcanopy layer of small trees, saplings, and tall shrubs on sites with deer management indicates a high potential for sapling recruitment to the canopy of the future forest
Data Collected for Report Entitled ''Evaluating Legacy Effects of Hyperabundant White-Tailed Deer in Forested Stands of Harriman and Bear Mountain State Parks, New York
No full textWhite-tailed deer (Odocoileus virginianus) are among the most impactful herbivores in the eastern United States. The lower Hudson Valley in New York has been heavily browsed by white-tailed deer since the early 20th century and the region has some of the lowest tree regeneration rates in New York State as a result of deer browsing and subsequent increases in interfering vegetation. The U.S. Geological Survey and the State University of New York studied sites where deer hunting is permitted (case sites) and nearby sites where hunting is currently prohibited (control sites) to assess and identify forest structure and composition differences. We used a case-control study and inferred recovery by comparing vegetation characteristics on adjacent sites in the lower Hudson Valley with similar forest communities and land uses but different deer population management histories. We surveyed more than 200 plots in upland forest types across case and control sites where we assessed forest condition by estimating density (number per unit area) and composition and cover (percent) of important vegetation constituents in ground, shrub, subcanopy, and canopy layers of the forest. We recorded 37 tree species, 22 shrub species, 57 herbaceous species, and 19 species of grasses and sedges in our plot surveys, including a number of nonnative and invasive plants. We also estimated the ages of a number of common canopy trees by counting rings from cores extracted from individual stems. Effects of more than 100 years of chronic deer browsing manifested in low herbaceous ground cover and little to no tree recruitment (saplings) on lands without deer management. In contrast, sustained deer management resulted in forests with conditions that indicated substantial recovery from chronic herbivory in the ground, shrub, and subcanopy layers. Sites with ongoing deer management exhibited greater ground cover of tree seedlings and herbs and less ground cover of interfering vegetation and nonnative species. The well-developed subcanopy layer of small trees, saplings, and tall shrubs on sites with deer management indicates a high potential for sapling recruitment to the canopy of the future forest
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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