Veld condition and trend in Kalahari duneveld under an extensive stock production system.

Abstract

Botanical data were collected for the period 1970 to 1985 from the experimental farm unit at Massakloutjie in the Kalahari duneveld of the north-western Cape Province (Veld type no. 16a4, Acocks, 1975). Rainfall during the trial period varied between 111 mm (1982-83) and 593 mm (1973-74). The total plant basal cover ranged from 2, 39% (1983) to 6, 17% (1977). The cyclical nature of the rainfall, with a sequence of wet and dry cycles, was reflected in the botanical composition of the duneveld. Group A of the rainfall, with a sequence of wet and dry cycles, was reflected in the botanical composition of the duneveld. Group A species (highly desirable decreaser species) form the dominant component (up to 90%) during dry cycles because of their drought tolerance. During wet cycles the group B, C and D species (less useful to poor increaser species) increase more rapidly than do the decreaser species and may comprise as much as 50% of the botanical composition. Because of this cyclical pattern in botanical composition (or relative cover), absolute cover provides a more reliable index of relative veld condition than botanical composition.

Keywords: basal cover; botanical composition; botany; cape province; decreaser species; drought; drought tolerance; increaser species; kalahari; net income; north-western cape; production; rainfall; south africa; stocking rate; veld condition