Implications of land use change for the production of plant biomass in densely populated Sahelo-Sudanian shrub-grasslands in north-east Nigeria

The production of plant biomass on small farms and in woodland in densely p opulated locations in the Nigerian Sahelo-Sudan is estimated in order to te st the hypothesis that conversion of land from natural vegetation to cultiv ation entails a loss in plant productivity. Estimates are given for reserve d forest, woodland, shrubland and farmland at two sites varying in mean ann ual rainfall and population density. The results fail to support the hypoth esis. The role of farmers in causing degradation through loss of plant prod uctivity, and appropriate conservation strategies, may require re-evaluatio n.