HERBACEOUS PHYTOMASS AND COMPOSITION CHANGES IN RELATION TO WOODY PLANT-DENSITY IN THE MIXED BUSHVELD OF THE NORTHERN PROVINCE, SOUTH-AFRICA

Herbaceous phytomass and composition were estimated on plots, which ha d been either untreated or treated with an arborcide, in two consecuti ve years, 1989/90 and 1990/91. There was a significantly greater phyto mass (P less than or equal to 0.05) on all the treated plots than on t he adjacent untreated plots in both years. Panicum maximum was largely responsible for the overall increase in phytomass. A significant decr ease in phytomass (P less than or equal to 0.05) occurred from the fir st to the second year on the treated and untreated plots. The decrease in phytomass was greater in the treated than in the untreated plots. This was mainly due to the much greater decrease in Panicum maximum on the treated plots than on the untreated plots.