Acaeia karroo encroachment is a serious ecological problem in certain veld types in South Africa. The growth and habitat requirements of A. karroo have not previously been studied in detail. This paper refers to an autecological study of the A. karroo seedling. Growth analyses indicate that the seedling is characterised by a low growth rate, that it is very sensitive to temperature changes and that light intensity is a less important ecological factor. The seedling is very sensitive to desiccation and it is suggested that under field conditions, favourable moisture conditions extending over a lengthy period together with high temperatures are the most important requirements for establishment. The possibility of a temperature boundary limiting the establishment of A. karroo is discussed and it is demonstrated that the average temperature climate of areas subject to A. karroo encroachment is very close to such a boundary. A. karroo encroachment can possibly be due to a temperature shift or to reduced grass compettion.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.