POPULATION ECOLOGY
Abstract Population density, one of the most funda-mental demographic attributes, may vary systematically with spatial scale, but this scale-sensitivity is incom-pletely understood. We used a novel approach—based on fully censused and mapped distributions of eastern grey squirrel (Sciurus carolinens...
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.484.771 http://people.trentu.ca/jschaefer/Mayor and Schaefer 2005 Oecologia.pdf |
| Summary: | Abstract Population density, one of the most funda-mental demographic attributes, may vary systematically with spatial scale, but this scale-sensitivity is incom-pletely understood. We used a novel approach—based on fully censused and mapped distributions of eastern grey squirrel (Sciurus carolinensis) dreys, beaver (Castor canadensis) lodges, and moose (Alces alces)—to explore the scale-dependence of population density and its relationship to landscape features. We identified popu-lation units at several scales, both objectively, using cluster analysis, and arbitrarily, using artificial bounds centred on high-abundance sites. Densities declined with census area. For dreys, this relationship was stronger in objective versus arbitrary population units. Drey density was inconsistently related to patch area, a relationship that was positive for all patches but negative when non-occupied patches were excluded. Drey density was neg-atively related to the proportion of green-space and positively related to the density of buildings or roads, relationships that were accentuated at coarser scales. Mean drey densities were more sensitive to scale when calculated as organism-weighted versus area-weighted averages. Greater understanding of these scaling effects is required to facilitate comparisons of population den-sity across studies. |
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