<i>Acacia karroo</i> intrusion: The effect of burning and sparing

Abstract

Abstract An investigation was conducted in the Eastern Cape sweetveld to determine the effect of frequency of burning, extended sparing and controlled grazing on the establishment of seedlings of A. karroo. After eradication of a mature. A. karroo stand, seedling establishment in the area concerned was recorded annually in permanent transects on paddocks neither grazed nor burnt, burnt annually, burnt biennially and burnt triennially. Grazing and resting treatments were superimposed on the burning treatment. After seven years reinfestation of A. karroo was determined on all paddocks and population height was sampled for evidence of layering. None of the treatments proved effective in preventing seedling establishment and there was no difference between treatments, seedling establishment being directly correlated to the original thorn tree density. Despite severe drought conditions there was a continuous establishment of seedlings, and at the termination of the trial no layering was evident in the community. Fire, while not preventing establishment, did retard seedling development.