LAUSR

Abstract Sustainable management strategies for trees are informed by research on growth rates and regeneration. In a 1998 study of bark thickness and tree size, six species (all used for traditional medicine) were sampled by removing 5 cm-diameter bark disks at four height intervals on 210 stems at 15 sites in South Africa. An impromptu revisit to one site in 2003 revealed that wounds for one species exhibited very little wound occlusion. These observations prompted a 2004 study on wound occlusion and stem growth for five of the species at six sites (Albizia adianthifolia, Balanites maughamii, Elaeodendron transvaalense, Searsia chirindensis, Warburgia salutaris), where 84 stems were re-measured. There were species-specific stem growth and wound occlusion rates. In general, annual lateral stem growth at 1.3 m was inversely related to stem size (corroborated by lateral widening responses of the original wound edges). There was also a tendency for smaller and/or faster growing stems to exhibit more wound occlusion and faster rates of bark regrowth – except in W. salutaris, where smaller individuals exhibited comparatively lower rates of occlusion compared to bigger individuals. All wound occlusion was by bark edge growth (typically