Some man-made changes in successional trends on the Rhodesian highveld.
Abstract
Several successional trends towards woodland were identified. A greater number of species was present in a felled wood than in an abandoned arable field, but the differences between them became less marked with time. Burning slowed the rate of successional change but did not alter its direction. Repeated burning and cutting, however, reduced the woodland to shrub savanna or even to Hyparrhenia-dominated grass savanna. Light grazing did not prevent the eventual development of woodland and, by introducing fast-growing trees, tended to accelerate the process. Continued heavy grazing resulted in the formation of a dense, persistent low sward of Cynodon dactylon. There was no evidence that severe grazing stimulated bush encroachment or stimulated development towards woodland. Recovery after 13 years of continued heavy grazing was rapid, tending towards grass savanna. Incomplete removal of rootstocks and larger roots during clearing resulted in the rapid formation of shrub savanna, tending towards woodland, while less frequent thorough clearing was followed by the development of grassland.