A demographic analysis of vole population responses to fragmentation and destruction of habitat |
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Authors: | Edda Johannesen Jon Aars Harry P Andreassen Rolf A Ims |
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Institution: | (1) Division of Zoology, Department of Biology, University of Oslo, Blindern, Oslo, Norway, NO |
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Abstract: | Fragmentation and destruction of natural habitats is currently considered to be the major threat to wildlife populations.
We here perform a comprehensive analysis of the demographic effects of habitat fragmentation and destruction on 14 populations
of the root vole. The experiment was divided into two consecutive periods. During the first period, we contrasted populations
with the same initial size and structure in continuous and fragmented habitat. During the second period, we fragmented the
continuous habitat into the same configuration as the permanently fragmented habitat so that the effect of habitat destruction
could be evaluated. We estimated survival and fecundity parameters and combined them into population projection matrices to
evaluate their relative impact on population growth. In the first period of the experiment there was no difference in population
growth rate between fragmented and continuous populations, although litter size was significantly higher in the continuous
populations. In the second period, we found higher population growth rates in populations that had experienced habitat destruction.
By applying the transition matrix model to empirical estimates of demographic parameters, we demonstrate that the difference
in population growth rate in the second period of the experiment was the result of a nonsignificant difference in adult survival.
Movements out of the habitat patches were significantly lower in populations that had experienced habitat destruction. We
conclude that predator-caused mortality of animals moving out of the habitat patches was the main determinant of demographic
variation in this system.
Received: January 31, 2002 / Accepted: March 25, 2003 |
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Keywords: | Capture– recapture modeling Demography Experimental model system Habitat fragmentation Microtus oeconomus Population transition matrix |
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