Age determination of Acacia erioloba trees in the Kalahari

Abstract

High quality wood core samples were collected from individual Acacia erioloba trees of unknown age in the Kgalagadi Transfrontier Park. In the majority of samples examined, seasonal changes were reflected in the wood anatomy as bands of marginal parenchyma on the polished surfaces of discs or cores. Estimated radiocarbon age was determined by means of 14C analysis for all samples. There was a strong correlation between the annual growth ring count and estimated radiocarbon age. A correlation was also found between age and stem circumference. Age structure of several A. erioloba populations in the Kgalagadi Transfrontier Park was subsequently determined. It could be demonstrated that the populations growing in the bed of the Nossob River showed poor recruitment; however, no clear relationship was found between flooding and regeneration of A. erioloba in the riverbed. The population growing in the dune field had a healthy age structure.