Does matrix resistance influence Red squirrel (Sciurus vulgaris L. 1758) distribution in an urban landscape? |
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| Authors: | Verbeylen Goedele De Bruyn Luc Adriaensen Frank Matthysen Erik |
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| Institution: | (1) Department of Biology - Laboratory of Animal Ecology, University of Antwerp (UIA), B-2610 Antwerp, Belgium;(2) Present address: Institute for Forestry and Game Management, B-9500 Geraardsbergen, Belgium;(3) Department of Biology - Evolutionary Biology Group, University of Antwerp (RUCA), B-2020 Antwerp, Belgium |
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| Abstract: | In determining isolation effects in fragmented populations, the landscape matrix is not often considered. Usually simple distance
measures are used to quantify degree of isolation. We tested the effect of the matrix on the presence of red squirrels in
354 wooded patches in the Brussels Region, by comparing several isolation measures. These were 1) distance to the nearest
source patch, 2) the Hanski-measure (a combination of distance to and size of all possible sources), 3) effective distances
calculated from different least cost models using the ArcView grid extension ‘Cost Distance’ (a combination of distance and
resistance of the landscape, with different resistances for different landscape types) and 4) some combinations of the Hanski-measure
and the effective distances. Size and quality of the target patches were always included in the tests of the predictive power
of different isolation measures on squirrel presence/absence. All variables examined (patch size, quality and isolation) significantly
influenced squirrel presence. Models using the effective distances gave the best results. Models including the Hanski-measure
improved significantly when Euclidean distance was replaced by effective distance, showing that parameterisation of matrix
resistance added significant additional explanatory power when modelling squirrel presence.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | Red squirrel Cost Distance Effective distance GIS Landscape resistance Patch isolation Patch quality Patch size |
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