The spatial scale of variability in small-mammal populations
We studied small-mammal populations across a range of spatial scales to determine which scales were relevant to demographic variability. We predicted that a scale of variability in population structure would occur at the scale of dispersal, which has previously been described as<200 m for some small-mammal species. Systematic live-trapping surveys were conducted on nested grids at three scales: 1) extent=4900 ha, grain=1000 m; 2) extent=306 ha, grain=250 m; and 3) extent=31 ha, grain=125 m. Prior to the present study, small-mammal populations had not been systematically live-trapped across a similar range of scales. From 1996 to 1998, surveys were conducted on a landscape intensively managed for timber, and on a reference landscape. Spatial analysis of abundance data demonstrated that small-mammal populations (four species) exhibited positive spatial autocorrelation at distances of between 133 and 533 m depending on the species and the landscape. No higher-order population structure was detected. Thus, within the range of scales we sampled, variability in small-mammal abundance occurred over short distances (i.e., 133–533 m).
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Document Type: Original Article
Publication date: June 1, 2000