The distinct effects of habitat fragmentation on population size |
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Authors: | Kathy W Herbener Simon J Tavener N Thompson Hobbs |
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Institution: | (1) Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO 80523, USA;(2) Program for Interdisciplinary Mathematics, Ecology and Statistics, Colorado State University, Fort Collins, CO 80523, USA;(3) Department of Mathematics, Colorado State University, Fort Collins, CO 80523, USA;(4) Natural Resources Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA; |
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Abstract: | We sought to understand how the separation of habitats into spatially isolated fragments influences the abundance of organisms.
Using a simple, deterministic model of population growth, we compared analytically exact solutions predicting abundance of
consumers in two isolated patches with abundance of consumers in a single large patch where the carrying capacity of the large
patch is the sum of the carrying capacities of the isolated ones. For the deterministic model, the effect of fragmentation
was to slow the rate of population growth in the fragmented habitat relative to the intact one. We also analyzed a stochastic
version of the model to examine the effect of fragmentation on population abundance when resources vary randomly in time.
For the stochastic model, the effect of fragmentation was to reduce population abundance. We proved in closed-form, that for
a non-equilibrium population exhibiting logistic population growth, fragmentation will reduce population size even when the
total carrying capacity is not affected by fragmentation. We provide a theoretical basis for the prediction that habitat fragmentation
amplifies the effect of habitat loss on the abundance of mobile organisms. |
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