1. Agroforestry is an approach to land-use that incorporates trees into farming systems, and allows for the
production of trees and crops or livestock from the same piece of land in order to obtain economic,
ecological, environmental and cultural benefits (Gordon and Newman, 1997). In North America, many
different types of agroforestry have been employed historically (Gordon et al., 1997), but the vast
potential for economic and environmental benefits attributed to agroforestry have yet to be realized on a
large scale. The main types of agroforestry systems currently being researched in many areas of North
America and in southern Ontario, applicable to portions of the Canadian landscape, would include
windbreaks and shelterbelt systems, silvipastoral systems, integrated riparian forest systems, forest
farming systems and tree-based intercropping systems.
Interaction in agroforestry is defined as the effect of one component of the system on the performance of
another component and/or the overall system (Nair, 1993). Rao et al. (1998) have indicated that the study
of interactions in agroforestry systems requires the examination of a number of complex processes,
including processes related to soil fertility, competition, microclimate, pest and diseases, soil conservation
and allelopathy. Exploitation of positive interactions between the woody (tree) and non-woody
(agricultural or annual crop) components and the minimization of negative interactions are the key to the
success of tree-based intercropping systems.
Positive interactions in agroforestry