Direct and indirect effects of fire on insect herbivore community structure in the Florida scrub

In fire-dependent habitats, the use of prescribed fire to increase local diversity has proven to be an effective restoration tool for many community types.  For insect herbivores, few studies have addressed the mechanism by which fire influences diversity patterns, and the effects of fire are largely assumed to be indirectly mediated through changes in host plant structure.  In this study, I examined the direct and indirect effects of fire on insect herbivore communities found on three co-occurring oak species (Quercus chapmanii, Q.  inopina, and Q.  geminata) in Florida scrub habitat.  I also investigated how changes in herbivore communities translated to damage patterns on the host plant species.

The results showed that the effects of fire varied according to herbivore assemblage.  Fire frequency directly influenced herbivore communities on Q. inopina, however indirect effects of fire, such as changes in vegetation density, surrounding landscape heterogeneity, and predator abundances, influenced community structure on Q. geminata and Q. chapmanii.  Damage patterns on host plant species were qualitatively similar across herbivore assemblage, both spatially and temporally.  This study showed that insect herbivore assemblages found on three co-occurring congeners responded differently to fire which may have implications for insect conservation.   For land-managers and restoration biologists interested in using prescribed fires as restoration tools, incorporating specific community-level responses to fire (as well as taxon-level responses) may be required in order to effectively increase local species diversity.