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David M Theobald

http://www.fs.fed.us/wwetac//projects/theobald.html Citation: Theobold, D.M., D.M. Merritt, and J.B. Norman, III. 2010. Assessment of Threats to Riparian Ecosystems in the Western U.S. A report presented to The Western Environmental Threats Assessment Center, Priveville, OR by The U.S.D.A. Stream Systems Technology Center and Colorado State University, Fort Collins, CO, 61p.
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These data were compiled as a part of a landscape conservation design effort for the sagebrush biome, and are the result of applying a spatially explicit model that assessed geographic patterns in sagebrush ecological integrity and used these results to identify Core Sagebrush Areas (CSAs), Growth Opportunity Areas (GOAs), and Other Rangeland Areas (ORAs). Our overall objective in this study was to characterize geographic patterns in ecological integrity of sagebrush ecosystems. These data represent the estimated integrity of sagebrush ecosystems, estimated from a spatial model that assigns high integrity is areas with abundant big sagebrush and perennial grass/forb cover and with minimal annual grass/forb cover,...
Tags: Arizona, Botany, California, Climatology, Colorado, All tags...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1111/conl.12322/full): Under rapid landscape change, there is a significant need to expand and connect protected areas (PAs) to prevent further loss of biodiversity and preserve ecological functions across broad geographies. We used a model of landscape resistance and electronic circuit theory to estimate patterns of ecological flow among existing PAs in the western United States. We applied these results to areas previously identified as having high conservation value to distinguish those best positioned to maintain and enhance ecological connectivity and integrity. We found that current flow centrality was highest and effective resistance lowest in areas that...
Quantifying landscape dynamics is a central goal of landscape ecology, and numerous metrics have been developed to measure the influence of human activities on natural landscapes. Composite scores that characterize human modifications to landscapes have gained widespread use. A parsimonious alternative is to estimate the proportion of a cover type (i.e. natural) within a spatial neighborhood to characterize both compositional and structural aspects of natural landscapes. Here I extend this approach into a multi-scale, integrated metric and apply it to national datasets on land cover, housing density, road existence, and highway traffic volume to measure the dynamics of natural landscapes in the conterminous US....
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The ecologically-relevant geophysical (ERGo) landforms dataset is a comprehensive classification of landforms based on hillslope position and dominant physical processes that covers most of North America. Four hillslope positions form a natural sequence of topographic units along the catena: ridges/peaks (summits), upper slopes (shoulders), lower slopes (foot slopes), and valley bottoms (toe slopes). The position within each of these hillslopes as a function of solar orientation to reflect how ecological processes (especially soil moisture and evapotranspiration) are influenced by insolation. Also included are very flat (i.e. areas 50°). We provide these data here at 30 m resolution, grouped by Landscape Conservation...
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