A preliminary investigation of woody plant increase in the western Transvaal and implications for veld assessment

The relationships between tree density and indices of pasture and soil condition were examined in Western Transvaal grasslands where Acacia karroo had increased following disturbance. The correlation between tree density and pasture condition was not linear, indicating a threshold in condition below which dramatic increase in trees is likely. Some evidence is presented for a second threshold where soil compaction inhibits seedling establishment and tree density declines. The necessity for assessing tree and soil status in addition to pasture condition is discussed and a variety of possible indicators of pasture, woody plant and soil status is considered.