The response of Acacia karroo plants to defoliation by hand compared to defoliation by goats.

Abstract

The leaf and shoot growth of Acacia karroo plants defoliated by goats was compared to that of plants in which leaf only or leaf plus shoot-tips were removed by hand, to simulate goat browsing. There were no differences in leaf or shoot production between plants whose leaf only was removed compared to those that had both leaf and shoot-tips removed. Leaf growth on the plants defoliated by goats at moderate levels was approximately three-fold that on plants defoliated moderately by hand. The plants defoliated by hand produced approximately twice the amount of leaf that the undefoliated plants produced. Heavy defoliation by both hand and goat, produced approximately half the leaf growth that moderately defoliated plants produced, following equivalent defoliation. Shoot production of all plants defoliated by hand was no different to that of the undefoliated control plants and was considerably less than that of the plants defoliated by goats.

Keywords: acacia karroo; browse production; browsing; clipping; defoliation; goats; growth stimulation; leaf growth; leaves; shoot growth; shoot production