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Spatial heterogeneity may have differential effects on the distribution of native and nonnative plant species richness. We examined the effects of spatial heterogeneity on native and nonnative plant species richness distributions in the central part of Rocky Mountain National Park, Colorado, USA. Spatial heterogeneity around vegetation plots was characterized using landscape metrics, environmental/topographic variables (slope, aspect, elevation, and distance from stream or river), and soil variables (nitrogen, clay, and sand). The landscape metrics represented five components of landscape heterogeneity and were measured at four spatial extents (within varying radii of 120, 240, 480, and 960 m) using the FRAGSTATS...
We conducted a 2-year field experiment to determine whether archery and muzzleloading hunting seasons caused elk to move prematurely onto private land during late summer. The study site was divided into north and south areas, and each area received both an early- and late-opening treatment. Early-opening treatment was an archery season that opened 1 week earlier (23 Aug) than the historical opening, and late-opening treatment was an archery season that opened 2 weeks later (13 Sep), yielding a 21-day difference in opening dates. We relocated 80 radiocollared female elk, captured at random locations on summer ranges, approximately 2 times per week for a 3-month period surrounding early- and late-opening dates each...
Movement of Rocky Mountain elk (Cervus elaphus nelsoni) to private land in Colorado, USA, is problematic for population management because once on private land, elk are largely unavailable for harvest. We evaluated the relative effects of reducing hunter numbers and changes in opening dates of early-season hunting (archery) on elk movement to private land during a 4-year field experiment. Our study area was divided into north (NTA) and south (STA) treatment areas. Eighty adult female elk were captured and radiomarked during July 1996. From 1996 to 1999, we relocated radiomarked elk 2 times per week for a 2- to 3-month period surrounding archery season opening dates, and we classified each elk location as being on...
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Synopsis: Researchers measured the effects of grassland amount and fragmentation on upland and wetland songbird and duck densities and nest success across 16 landscapes in southern Alberta. By comparing these landscape-level effects with local-scale responses, including distance to various edges and vegetation characteristics, the study demonstrated that few species were in fact influenced by grassland amount or fragmentation. In contrast, distance to edge and local vegetation characteristics had significant effects on densities and nest success of many species. Landscape level effects were much less apparent when local characteristics were included in the models. Therefore, researchers concluded that local habitat...
Interaction Assessment (INTASS) is a field and analytic methodology for constructing population dynamics models. Because data collected in generating a model for one species comprise much of the information needed for other species, a small increase in effort can result in simultaneous expressions for the dynamics of multiple species. These expressions can be used to simulate whole community responses to environmental change, including management actions. Since publication of the most recent paper in this series, the INTASS methodology has undergone a large number of developments. These include the use of conceptual models to direct field and modeling efforts and incorporation of an information theoretic approach...
Two populations of boreal toads (Bufo boreas) experienced drastic declines in abundance in the late 1990s. Evidence supported the hypothesis of disease (the chytrid fungus, Batrachochytrium dendrobatidis) as the cause of these declines, but other hypotheses had not been evaluated. We used an 11-year capture-recapture data set to evaluate weather and disease as causes of these declines. We developed sets of mathematical models that reflected hypothesized relationships between several weather variables and annual survival rates of adult males in these populations. In addition, models that reflected the possibility that the declines were caused by an introduced fungus were developed. All models were fit to the data...
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We investigated butterfly responses to plot-level characteristics (plant species richness, vegetation height, and range in NDVI [normalized difference vegetation index]) and spatial heterogeneity in topography and landscape patterns (composition and configuration) at multiple spatial scales. Stratified random sampling was used to collect data on butterfly species richness from seventy-six 20 � 50 m plots. The plant species richness and average vegetation height data were collected from 76 modified-Whittaker plots overlaid on 76 butterfly plots. Spatial heterogeneity around sample plots was quantified by measuring topographic variables and landscape metrics at eight spatial extents (radii of 300, 600 to 2,400 m)....


    map background search result map search result map Effects of spatial heterogeneity on butterfly species richness in Rocky Mountain National Park, CO, USA A multi-scale analysis of avian response to habitat amount and fragmentation in the Canadian dry mixed-grass prairie. Effects of spatial heterogeneity on butterfly species richness in Rocky Mountain National Park, CO, USA A multi-scale analysis of avian response to habitat amount and fragmentation in the Canadian dry mixed-grass prairie.