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SUMMARYThe effects of defoliation of Cynoglossum ojficinale L. and Verbascum thapsus L. on growth, net assimilation rate and dry matter distribution were studied under various nitrogen regimes. At high levels of nitrogen supply, there was a higher net assimilation rate (NAR) and a higher leaf weight ratio in defoliated plants than in undefoliated plants resulting in a faster growth of defoliated plants. In V. thapsus growth of defoliated plants did not differ significantly from undipped plants. In a low nitrogen regime all defoliated V. thapsus plants died. In the same regime C. officinale had a low NAR and thus showed little regrowth. Leaf nitrogen content was not significantly different from control plants.

The extent and impact of the utilisation of Aloe ferox by Boer goats during winter in a South African savanna was determined using a plant-based approach. All Aloe plants rooted within the transects were eaten by goats, with small plants utilised more frequently than tall plants. The density of dying and dead Aloe plants was significantly greater than live plants. Mortality of Aloe ferox was a result of extensive browsing by Boer goats. The future survival of Aloe ferox in this savanna system is highly unlikely.

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An analysis of the vegetation of Goedverwacht farm in the mixed bushveld of the Northern Province is presented. Releves were compiled in 33 stratified random sample plots. Eight distinct plant communities were identified by means ofBraun-Blanquet pro-cedures. Detrended correspondence analysis (DCA) was applied to the floristic data set using the computer programme DECORANA (Detrended Correspondence Analysis) to determine a probable environmental gradient and to facilitate in the identification of management units. The computer programme CANOCO (Canonical Correspondence Analysis) was used to apply canonical correspondence analysis (CCA) to the floristic data set. Two management units were determined by means of vegetation ordinations and soil data. A classification, description and ecological interpretation of the plant communities as well as a description of the management units are presented