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Repeat photography samples were used to analyze how the structure and site-specific distribution of forests may or may not have changed during the past century in the San Juan Mountains, Colorado. Systematic evaluation of 146 photosets was combined with field observations to identify trends in vegetation change. Both conifers and deciduous trees (e.g., aspen) have increased in extent. Forest recovery from large disturbances that occurred during Euro-American settlement contributed substantially to this increase. Trees also encroached into grass/shrublands, but less than half of photosets show tree invasion, and invasion is more common in small grass/shrubland openings interspersed with forest than in large openings....
A habitat-change model was used to compare past, present, and future land cover and management practices to assess potential impacts of alternative agricultural practices on wildlife in two agricultural watersheds, Walnut Creek and Buck Creek, in central Iowa, USA. This approach required a habitat map for each scenario based on soil type and land cover, a list of resident species, and an estimate of the suitability of each of 26 habitat classes for every species. Impact on wildlife was calculated from median percent change in habitat area relative to the present. Habitat classes with the highest species richness for native vertebrates were ungrazed riparian forest, upland forest and wet prairie. Differences in habitat...
Degradation, fragmentation, and loss of native sagebrush (Artemisia spp.) landscapes have imperiled these habitats and their associated avifauna. Historically, this vast piece of the Western landscape has been undervalued: even though more than 70% of all remaining sagebrush habitat in the United States is publicly owned, <3% of it is protected as federal reserves or national parks. We review the threats facing birds in sagebrush habitats to emphasize the urgency for conservation and research actions, and synthesize existing information that forms the foundation for recommended research directions. Management and conservation of birds in sagebrush habitats will require more research into four major topics: (1) identification...
1. A wide range of spatially explicit simulation models have been developed to forecast landscape dynamics, including models for projecting changes in both vegetation and land use. While these models have generally been developed as separate applications, each with a separate purpose and audience, they share many common features. 2. We present a general framework, called a state-and-transition simulation model (STSM), which captures a number of these common features, accompanied by a software product, called ST-Sim, to build and run such models. The STSM method divides a landscape into a set of discrete spatial units and simulates the discrete state of each cell forward as a discrete-time-inhomogeneous stochastic...
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Synopsis: Large-scale patterns of land use and fragmentation have been associated with the decline of many imperiled wildlife populations. Lesser prairie-chickens (Tympanuchus pallidicinctus) are restricted to the southern Great Plains of North America, and their population and range have declined by > 90% over the past 100 years. Our objective was to examine scale-dependent relationships between landscape structure and change and long-term population trends for lesser prairie-chicken populations in the southern Great Plains. We used a geographic information system (GIS) to quantify landscape composition, pattern and change at multiple scales (extents) for fragmented agricultural landscapes surrounding 10 lesser...
    map background search result map search result map Multi-scale effects of habitat loss and fragmentation on lesser prairie-chicken populations in the US souther Great Plains. Multi-scale effects of habitat loss and fragmentation on lesser prairie-chicken populations in the US souther Great Plains.