Invasion and control of alien woody plants on the Cape Peninsula Mountains, South Africa — 30 years on

Abstract

The distribution and density of 14 taxa of woody introduced species on the Cape Peninsula were re-assessed from 87 sample sites which were initially established in 1959/60. Trends over the last 30 years suggest that carefully planned intensive clearing programmes can contain, and possibly even eradicate, these aggressive alien species if adequate funding is allocated. Of concern is that Pinus radiata and Acacia cyclops have shown a significant increase in frequency of occurrence — both species in the past have not been considered as particularly aggressive invaders on the Peninsula mountains., The density of some species, particularly the most widespread ( Pinus pinaster), have been reduced from 82% to 62% of sites but they still remain a threat. Biological control measures for Hakea sericea and Acacia longifolia are apparently effective. The main conservation management problem in the area is the lack of funds and a single controlling agency.