The effects of fire on vegetation structure and habitat in broadleaf savannas

Fire in savannas is instrumental in creating heterogeneous vegetation
structures and a patchwork landscape in savannas. The frequency and
season of fire have a direct effect on plant community composition and
vegetation structure. In turn this has implications for faunal composition
and diversity, since vegetation provides both habitat and food for
herbivores. This study found that burn regime has a marked effect on both
the structure and composition of the floral components. Infrequently burnt
sites have a higher proportion of larger trees and denser tree and grass
cover. These sites were dominated by climax, decreaser and mostly
palatable grasses. More frequently burned sites have fewer large trees and
more small trees. Frequent fires continually knock back woody vegetation
to small sizes. This fire trap results in a high proportion of seedlings and
gullivers. Grass communities mainly comprise pioneer increasers of
moderate to low palatability. Ant species richness increased with
increasing canopy cover, possibly because more canopy results in a greater
diversity of thermal niches. Bird communities closely followed variation
in vegetation due to differing burn regiments. Bird communities in more
frequently burned sites were more closely related to each other than less
frequently burned sites. These findings support the policy of managers of
Kruger National Park with respect to promoting patch heterogeneity.
Heterogeneity of ecosystems does indeed promote biodiversity of fauna in
all its natural facets and fluxes. Fire is a powerful tool for managers
hoping to drive this heterogeneity.