Cascading extinctions in spatially coupled food webs

• The spatial structure of ecological communities as well as the dynamics and structure of local communities can be expected to have important consequences for the long-term persistence of metacommunities, that is, their resistance to different kind of perturbations. The aim of the present work is to investigate how web connectance of local communities and number of local habitat patches affects a metacommunity’s response to the global loss of a species. We find that the inclusion of space significantly reduces the risk of global and local cascading extinctions. It is shown that communities with sparsely connected food webs are the most sensitive to species loss, but also that they are particularly well stabilized by the introduction of space. In agreement with theoretical studies of non-spatial habitats, species at the highest trophic level are the most vulnerable to secondary extinction, although they often take the longest time to die out. This is particularly pronounced in spatial habitats, where the top predators appear to be the least well adapted to exploit the stabilizing properties of space.

Nyckelord

Cascading extinction

dispersal

food web connectance

habitat destruction

metacommunity

spatial structure

species interactions

species loss

NATURAL SCIENCES

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