Data from: Fire may mediate effects of landscape connectivity on plant community richness in prairie remnants

Following the predictions of island biogeography and metapopulation
theory, efforts to understand and maintain plant communities have focused
on spatial attributes such as patch size and connectivity. However,
despite a large body of literature, the effects of these spatial
attributes remain uncertain, and accumulating evidence suggests that they
may interact with local patch characteristics. Here, we assess the role of
spatial attributes (patch size and connectivity at two time periods) and
of patch quality (indicated by number of years since last fire, as this is
a fire-dependent system) in determining plant species richness at 63
remnant prairie sites in Wisconsin, USA. Our results demonstrate
significant main effects of patch size, with larger patches being richer
than small patches, and of fire, with recent-fire sites being richer than
fire-excluded sites. We also report a novel interaction between number of
years since fire and patch connectivity. Historical (1950) connectivity
was negatively related to species richness at recent-fire sites, but
positively related to species richness at fire-excluded sites, while
current (2000) connectivity and species richness were positively
correlated at recent-fire sites, but unrelated at fire-excluded sites. Our
findings indicate that measures of patch quality such as time since last
fire can alter the association between spatial attributes such as patch
size or connectivity and species richness.