... Medium-Term Plan 199 8-2 000, ICRAF, Nairobi, Kenya.Ingram, J., 1990. The role of trees in maintaining and improving soil productivity — a reviewof the literature, in Agroforestry for Sustainable ... since in addition to their biodiversity these multistrata damar agroforests in Sumatra arefinancially attractive.Damar resins are utilized by industries in Indonesia or exported worldwide. In 1984, ... diversifying and intensifying agroecosystems in a way that is beneficial tothe environment and can maintain and perhaps enhance biodiversity (Sanchez andLeakey, 1998; Sanchez et al., 1998). In its...