The assessment of yields in social forestry must include diverse types of biomass which provide inputs to agro ecosystems. When the objective of tree planting is the production of fodder or green fertiliser, it is relevant to measure crown biomass productivity. India, with its rich generic diversity in plants and animals, is endowed with venous types of trees which have annual yields of crown biomass that are much higher than the total biomass produced by Eucalyptus as indicated in Table 5.12 An important biomass output of trees that is not assessed by foresters, who look only for timber and wood, is the yield of seeds and fruits. Fruit trees, such as jack, jamun, mango and tamarind, have been important components of indigenous forms of social forestry as practiced over centuries in India. After a brief gestation period fruit trees yield annual harvests of edible biomass on a sustainable and renewable basis.
Tamarind trees yield fruits for more than two centuries.
Other trees such as, neem, pongamia and sal, provide an annual harvest of seeds which yield valuable non-edible oils. These diverse yields of biomass provide an important source of livelihood for millions of tribal or rural people. Coconut, for example, besides providing fruit and oil, provides leaves for thatching huts and supports the large coir industry in the country. Since social forestry programmer in their present form have been based only on the knowledge of foresters who have been trained to look for woody biomass in the tree, these important high yielding species of other forms of biomass have been totally overlooked in these programmer. Two species which have been emphasized in ancient farm forestry systems in arid zones are pongamia and tamarind.