Ecological Network Meltdown from Habitat Loss and Fragmentation

Abstract Human-induced habitat alteration is the major cause leading to biodiversity loss and eventually to ecosystem collapse. The response of communities to habitat loss depends on both species’ characteristics and the extent to which species interact. In this sense, habitat destruction may yield qualitatively new consequences when considering species that are embedded in an intrincate web of ecological relationships. Here we review the theory linking habitat loss and food webs, from single predator-prey interactions to large food webs. We present a new multitrophic model for simulating the dynamics of multispecies ecosystems in fragmented landscapes. The model shows that as habitat destruction increases, predators are lost first, then herbivores and finally producers. But the interaction between trophic levels yields new outcomes not predicted when a single trophic level is observed alone, as trophic cascades. Our analysis of multispecies ecosystems indicates that the effects of habitat loss and those of network structure interact in new but predictable ways, and, therefore, their integration is necessary and useful for a deep understanding of the effects of habitat alteration on ecosystems.