Agroforestry is defined as a land-use system in which woody plants [often multipurpose tree species] are grown in association with agricultural crops, pas tures or livestock (Breman and Kessler, 1997). Such systems have the potential to increase yields by effectively growing two crops at the same time on a single piece of land (Nair, 1991), and have been promoted as more sustainable agricultural production systems appropriate for developing countries where the use of external inputs is not feasible (Winterbottom and Hazelwood, 1987). Several reasons have been suggested for combining trees and crops on the same