Original Articles

Costing the initial clearance of alien Acacia species invading fynbos vegetation

Published in: South African Journal of Plant and Soil
Volume 6, issue 1, 1989 , pages: 39–45
DOI: 10.1080/02571862.1989.10634477
Author(s): I., A.W. Macdonald, Republic of South Africa, C. Wissel, Federal Republic of Germany

Abstract

The costs of the initial clearing of mixed stands of the alien Acacia cyclops and A. saligna invading fynbos vegetation were compared in a replicated trial on the Pella Fynbos Research Site. Costs were estimated using a regression-based model of the individual cost components. Felling was the cheapest clearing method, with felling plus the stripping of bark from the cut stump, second. Applying arboricides to the cut stump generally doubled the cost relative to felling. Mattocking was the most expensive method with ringbarking second. The estimated cost of clearing a moderate infestation on the Pella site ranged from R26 to R286 ha−1 for the different treatments. Similarly, estimations for an ‘average’ western Cape Acacia thicket ranged from R526 to R2 408 ha−1 while those for the densest infestations encountered on Pella ranged from R299 to R5 170 ha−1. The precision of the model is thought to be low at higher densities. Variations in the density and height of the fynbos and the spatial distribution, size class distribution and growth form of the Acacia plants are all thought to affect clearing costs.

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