Fire and bush nucleation in broadleaf savannas

The effects of fire on the spatial distributions of trees and shrubs have been largely
ignored in investigations on the role of fire in savanna ecosystems. This study
examined bush clumping around large trees in experimental burn plots near
Pretoriaskop, Kruger National Park in South Africa. Nucleation of established
individuals (ht>1m) occurs in the absence of fire. These bush clumps are
characterized by a switch to forest and mixed forest species. Annual burn plots and
open areas of no burn plots are dominated by bushveld species. This suggests that
fire plays a vital role in preventing forest encroachment into savannas and in
maintaining the savanna state in the Pretoriaskop area. This area is characterized by
higher rainfall (>650mm/annum) which may make the area appropriate for forest
encroachment.