A challenge for agroforestry research is to develop economically and socially acceptable landuse systems that function like undisturbed ecosystems and maintain biodiversity. Note that low input and high input continuous cultivation both had negative net present values. Table 2 . The latter are all those organisms, above and below ground, that have found niches to fill among the planted trees and crops. There is a need for controlled experiments to determine these relationships between intensification and biodiversity.
Species also vary in their importance in different food webs, where scale is important.
These patches are often critical components of a farmers environment, being a source of products and environmental services of importance to their livlihood and welfare. As biogeographical islands, their role in maintaining biological diversity is also crucial. It is not known, however, the species-area relationships apply when habitats are being expanded. At present it is only genetic diversity which is getting any attention. Agroforestry, because of its production orientation, is promoting the retention and introduction of genetic diversity among the tree species planted by farmers.