Leguminous trees for shade

Abstract

Use of leguminous trees to provide shade, especially in perennial crops, would appear to be an ancient agricultural practice, probably coinciding with the domestication of perennials such as tea, coffee and cocoa. Leguminous trees can also be found in association with annual crops, in pastures, and in situations such as living fenceposts, where shade is not clearly being provided to an associated species. The factors which influence the choice of leguminous as opposed to non-leguminous trees to provide shade in such situations are considered. Various such associations are described in some detail, in an attempt to elucidate some of the ecological interrelationships that are probably reflected in traditional agroforestry practices. It is concluded that not only the possibility of improving nitrogen nutrition but algo other characteristics, such as type of shade, coppicing ability and ease of husbandry, might have favored the selection of leguminous trees for shade. Many of these areas would appear to merit considerably more research with the objective of obtaining more quantitative data than is presently available.