Forestry in the humid tropics requires new ways of thinking or rather a
reorientation towards basic principles of overall sustainability. Trees and
shrubs are urgently needed to serve on agricultural and grazing lands which
leads to agroforestry systems like alley farming, shade and mulch trees in
plantations with perennial crops such as coffee or cocoa, and live fences, etc.
Trees and shrubs are also applied to prevent erosion and to improve soils
through "nutrient pumping" and nitrogen fixation. Specific forms of
forestry are applied to serve rural people, including farm forestry, community
forestry and social forestry.