干旱区生态环境知识资源中心

Studies of environmental change and degradation in semi-arid Africa often present contradictory results of the magnitude, severity, causes and effects of observed changes. Central questions are how findings may be generalized and extrapolated, how perceptions of the environment are recognized and analysed, and how value-judgement terms are defined and used. Emerging theories about dryland ecosystem dynamics, and ideas on interdisciplinary research, formed the background for a geographical study of the environmental history of an agropastoral communal area in North East District, Botswana. Here a comprehensive and discursive summary of the main conclusions of this study is presented. Using methods from the social and natural sciences, environmental outcomes were linked to different ’types’ of change, such as effects of isolated events, of cyclic variation, and of trends.

Since the beginning of the twentieth century, the area has been described as severely degraded, but the present results contradict previous descriptions and instead describe a temporally fluctuating, and spatially heterogeneous, environment with few signs of deterioration. Many changes were caused by isolated physical and social events, while others occurred in cycles. The few long-term ’causative’ trends identified showed only small environmental impact. Several variables used as degradation indicators were identified, but found to constitute natural phases in the interaction of biophysical and socio-economic processes. The local understanding of environmental change corresponds quite closely with recent scientific thinking, and this study definitely supports the need for reevaluations of past ’truths’ about environmental change in semi-arid Africa. Copyright (C) 2000 John Wiley & Sons, Ltd.