干旱区生态环境知识资源中心

The growing urgency of the need to arrest land degradation makes it essential to establish the relative importance of climatic and anthropogenic factors in the process. This requires a longer perspective than thal provided by the wide range of official records which refer mainly to this century. Here a preliminary assessment of the potential of employing micromammalian community structure to monitor environmental conditions indicates that its potential is good but likely to be more difficult to realize in those arid and semi-arid regions most at risk. Evidence of distress in micromammalian communities during the last millennium largely fits the pattern predicted if farming is the principal agent. Such evidence is found earlier in the more mesic east where settled agriculture has been practised for over 1 000 years; in the drier parts, which were occupied by more or less itinerant pastoralists until about 100 years ago, no evidence of artificial change is detected until modern times. In addition there is evidence of response to climatic change during the past in the arid and semi-arid central region, and possibly the highlands of Natal, but not in the more equable areas of the western Cape Province and Transvaal.