Testing the intermediate disturbance hypothesis: do species richness and diversity of savanna trees and rodents peak at intermediate levels of fire intensity?

: In this study, we sought to test the intermediate disturbance hypothesis (IDH) in the context of an African savanna, with fire as the disturbance. To do this, we measured the species richness and diversity of woody vegetation as well as rodents in a series of experimental burn plots which have been burned at different fire intensities since 1954. We found that species richness and diversity did not peak at intermediate levels of disturbance, as the IDH predicts. For woody vegetation, species richness and diversity decreased with increasing intensity. We attribute this result to the establishment of fire intolerant forest species in the plots with low fire intensity. For rodents, species richness increased with increasing fire intensity. We concluded that this result was due to the increase in vegetation density with increased fire intensity, affording rodents greater protection from predation and thus allowing species richness to increase. Our findings show that the IDH is not universally applicable and that ecologists and conservation managers need to take a variety of factor into consideration when studying the effects of disturbance on species richness and diversity.