State-of-the-art of agroforestry systems

Abstract

Agroforestry, often paraphrased as ‘a new name for an old practice’, represents the coming of age of some age-old land-use systems involving trees, especially in the tropics and subtropics, and the recognition of their sustained yield potentials, conservation benefits, and multiple output possibilities. Examples of low-input agroforestry systems, in which woody perennials are deliberately mixed or retained with crop- and/or animal production units with a view to optimizing the economic and ecological benefits from the resultant interactions, are many in different parts of the world. However, the major types of agroforestry practices that constitute these different systems can be narrowed down to a few. The results of a global inventory of tropical and subtropical agroforestry systems undertaken during 1982–1987 showed that the existence or adoption of an agroforestry system in a given area is determined primarily by the ecological potential of the area, but the socio-economic factors determine the complexity of the system and the degree of intensity of its management. There are some agroforestry approaches that are common to many ecological regions, but the nature of components that constitute the systems in any specific region will vary depending upon site-specific factors. Additionally, there are some systems and approaches that are particularly appropriate in specific ecological conditions. Important among such specific agroforestry approaches in humid and subhumid tropical lowlands are homegardens, plantation crop combinations, multilayer tree gardens and various intercropping systems including alley cropping. Silvopastoral systems, windbreaks and shelterbelts, and multipurpose trees on farm lands, are the major specific approaches for arid and semi-arid lands, whereas, soil conservation hedges, silvopastoral combinations, and plantation crop systems are common in the tropical highlands. Improved tree fallows in shifting cultivation areas, modified taungya, use of underexploited woody perennials, multilayer tree gardens, tree folders and other aspects of silvopastoral management are some agroforestry approaches to multiple use management of tropical forests. The main examples of agroforestry systems in the industrialized and temperate regions are silvopastoral systems of tree + cattle/grass combinations, and intercropping systems involving hardwood and nut trees. Practically very little scientific effort has been made to increase the productivity of most of these indigenous systems, so that their potentials are far from being understood, let alone exploited. The main program directions in agroforestry in this second decade of agroforestry development are internationally-funded development projects, research initiatives, and education and training programs. The current trend seems to be to concentrate on development projects almost at the exclusion of academic programs of research and education. This is an unhealthy trend and it needs to be reversed. Fortunately, there is a growing interest in agroforestry in different academic circles, but it cannot be sustained and exploited unless the efforts are backed up by financial support. International and bilateral funding agencies are urged to provide financial support to academic programs in agroforestry, not only in developing countries, but also in developed countries, which could be of great benefit world-wide.