The Physical Importance of Forest Cover in the East African Highlands

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Pereira H. C.
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The belief that the presence of large areas of forest may be the direct cause of local rainfall has been widely held since the close of the last century, when scientists, both in Germany and France, reported rainfall readings in forested areas to be higher than those measured in the immediately surrounding arable countryside. With the advance of our knowledge of meteorology, and of the techniques of rainfall measurement, it has become apparent that such effects need very large-scale experimental studies with adequate statistical planning. The complexity, long duration and expense of such studies are illustrated in the reports by Wicht [1] and by Rycroft [2] of the 20 years of forest hydrology measurements in the Union of South Africa. The specific evidence is slender because few countries have had the staff or the foresight to lay down such experiments. Hughes [3] in 1949 briefly surveyed the principal sources of evidence applicable to East Africa, concluding that the effects of forest on rainfall (as apart from local climate) are "not yet proven". Hursh [4] has since published results of a study in Tennessee which is particularly relevant to East Africa, where the resources devoted to such work are still extremely slender. Hursh's evidence is discussed later in this paper.
East African Agricultural And Forestry Journal, XIX (No. 4), p. 233-236