Agroforestry systems in major ecological zones of the tropics and subtropics

P.K.R. Nair

ICRAF, through its Agroforestry Systems Inventory (AFSI), has collected, evaluated, synthesized and disseminated information on existing agroforestry (AF) systems and practices from different parts of the tropics and subtropics. The systems have been classified according to various criteria such as their structure, function, socio-economic aspects, ecological spread, and so on. But the primary step in classifying them is on the basis of their structure; thus there are three basic types of 'AF systems

• agrosilvicultural (crops land trees)

• silvipastoral (trees and pasture/animals), and

• agrosilvipastoral (crops + pasture/animals + trees).

Under each of these major AF types, several systems have been recorded in the AFSI data base. But the distinct AF practices that constitute these systems are only a few; these are discussed in the paper.

An ecological analysis of the spread of various AF systems shows that the existence / adoption of an AF system in a given area is determined primarily by the ecological potential of the area, but socio-cultural and economic factors determine the complexity of the system and the degree of intensity of its management. From a purely ecological point, certain types of systems can be identified as characteristic of each major ecological region.