The grazing index method of range condition assessment

Abstract

Owing to the difficulty of examining succession theory in the Karoo, it is suggested the ecological index method (EIM), be replaced by the grazing index method (GIM), through the introduction of grazing index values (GIV) for Karoo plant species. The GIM may provide more acceptable range condition scores and more realistic estimates of the current grazing capacity. Using GIVs, arrived at by scoring the agronomic attributess of the plant species(productivity, forage value, perenniality), the estimated current grazing capacitiesare found to be closely similar to the grazing capacity norms established for the different agro-ecological areas in the Karoo. The manner in which the range condition survey is conducted and the application of the grazing index method, ensures the computation of a figure representative of the agronomic potential of the area to support livestock. The cover figure and the range condition score determined for a sample site, can be employed in monitoring the trend in changes in the vegetation, brought about by climatic and biotic variables. Grazing capacity norms are closely related to median annual precipitation (r² = 0.96 and 0.68 respectively).

Keywords: botany; canopy spread cover; current grazing capacity; ecological index method; grazing capacity; grazing index method; grazing index values; index; method; monitoring; range condition; range condition score; South Africa

African Journal of Range and Forage Science 1995, 12(2): 61–67