'Fire is a natural factor in and a condition for many savanna ecosystems. It is caused naturally by, for example, lightning. For thousands of years in southern Africa man has also induced fires by accident or voluntarily for hunting purposes or to provide fresh grazing for livestock. Lately, burning has been used in range management in order to control encroaching shrubs or to keep the field layer in a desired condition. A small grazing ecology project is working in the western Kalahari under the supervision of the Ministry of Agriculture, Botswana. The two study areas were burnt by accident in the dry season of 1977 (Fig. 1). As background data on the vegetation were available, some effects of the fires were followed up in order to get an idea of the reaction to fire of vegetation that was not stressed by grazing. Serious limitations to the applicability and comparability of the results are that the two areas burnt at different times, in July and September respectively. and with different intensity, and that no unburnt areas were available as reference.'