Sixty to more than 90% of SEA are upland areas. Before, these areas were sites of undisturbed natural forests. However, rapid population growth resulted in upland migration. Upland migrants have now no choice but to cultivate the land for a living, thus, transforming natural forests to agricultural lands. This transformation has lead to problems such as soil acidity, domination of Imperata, and soil erosion - all boiling down to soil infertility. Introduction of agroforestry systems through contour planting, natural vegetative strips, improved vegetative strips and rotationally alley cropping does not only improved soil fertility but also effectively control soil erosion, thus conserving the fertile topsoil and water. Other agroforestry systems that include planting of timber and fruit trees, which are scattered in the farm (parkland) or along farm boundaries, improve the sustainability of the farming system.