How patchy landscapes drive spatial patterns

Habitat fragmentation is an increasing problem that threatens the integrity of a wide range of ecosystems. Once divided, networks of patchy habitat in different spatial configurations may vary in their capacity to attract and retain biological communities. In some cases, when habitat-forming organisms (such as corals or trees) benefit from a thriving community of residents, differences in colonization patterns or occupancy caused by variable patch arrangement could affect the entire system. One of the major mechanisms for this phenomenon, known as “propagule redirection”, occurs when nearby habitat dilutes the per-patch concentration of colonizing individuals by providing a refuge from density-dependent competition and mortality. In the paper “Landscape configuration drives persistent spatial patterns of occupant distributions”, recently published in Theoretical Ecology, we explored the circumstances under which the configuration of habitat patches would be expected to lead to differences in biological community structure. To do so, we created a model which was parameterized and applied to data collected from coral reef fishes. We found that persistent effects on community composition were more likely when settlement pulses were small and infrequent, and when density-dependent mortality was low. The influence of patch configuration was comparable to the effects predicted from variation in patch quality, a much more commonly described driver of colonization patterns in fragmented habitats. Our demonstration that different spatial configurations of habitat patches can affect biological communities is an important step toward understanding how ecosystems may respond to fragmentation, and the framework we have built may be useful to both scientists and managers studying the ecology of fractured landscapes.

Hamman E.A., Osenberg C.W., McKinley S.A., and A.C. Stier. Spatial patterns of symbionts arising from propagule redirection. Theoretical Ecology. PDF

post authored by J. Curtis.

Adrian Stier