Bosindringing met spesifieke verwysing na acacia karroo‐indringing¹

Verwerk van M.Sc.‐verhandeling voorgelê aan Dept. Weidingsleer, Universiteit Pretoria, Januarie 1966.

Abstract

Uittreksel

Acacia karroo‐indringing is ‘n ernstige ekologiese probleem in sekere veldtipes in Suid‐Afrika. Die groei‐en habitatsvereistes van A. karroo is voorheen nie in besonderhede bestudeer nie. Hierdie referaat handel oor ‘n outekologiese studie van die A. karroo‐saailing. Groei‐analises dui aan dat die saailing deur ‘n lae groeitempo gekenmerk word en dat dit baie gevoelig vir temperatuurskommelings is, maar dat ligintensiteit ‘n minder belangrike ekologiese faktor is. Die saailing is besonder gevoelig vir uitdroging en dit word aan‐gevoer dat onder veldtoestande, gunstige vogtoestande oor ‘n lang tydperk tesame met hoë temperature die belangriksle vestigingvereistes is. ‘n Moontlike temperatuurgrens vir die vestiging van A. karroo word bespreek en dit word gedemonstreer dat die gemiddelde temperatuurklimaat van dele wat aan A. kurroo‐indringing onderhewig is, baie na aan hierdie grens is. A. karroo‐indringing kan moontlik aan ‘n tempera‐tuurverskuiwing of aan verswakke graskompelisie toegeskryf word.

Abstract

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.

Notes

Verwerk van M.Sc.‐verhandeling voorgelê aan Dept. Weidingsleer, Universiteit Pretoria, Januarie 1966.

Tans by Landbounavorsingsinstituut Dohne, Stutterheim, K.P.