Abstract
Agricultural expansion has markedly reduced forests and reconfigured
landscapes. These changes incur a well-known detrimental impact on the
biodiversity of local forest patches, but the effects on species
persistence at entire landscapes comprised of multiple patches are
debated. We investigated how regional diversity is affected by habitat
loss, fragmentation, and cattle grazing, and how species respond to
deforestation both locally and regionally. We also investigated how the
heterogeneity in species distribution (beta-diversity) buffers
landscapes against local diversity losses. The vast majority of the 251
ant species found in our study were negatively affected by both habitat
loss and cattle at local forest patches, drastically reducing diversity
at these patches compared to pristine forests. Despite local declines in
diversity, however, heavily fragmented landscapes could still retain
most species due to the high heterogeneity in species distribution. We
found that beta-diversity is the main component of regional diversity.
Results from several studies suggest that this component is maximized
when remnant primary habitats in a landscape are spread across vast
areas. Although preserving local diversity may be important for the
adequate functioning of the ecosystem locally, our results indicate that
the maintenance of many small forest patches in a landscape can buffer
regional biodiversity against local species losses. Our results suggest
that even small forest remnants in otherwise deforested landscapes can
prevent most regional-scale species extirpations, and therefore also
merit conservation efforts.