HISTORICAL-ANALYSIS OF CHANGES IN LAND-USE AND CARBON STOCK OF VEGETATION IN SOUTH AND SOUTHEAST-ASIA

A time series (1880, 1920, 1950, 1980) of estimates of land use and carbon content of vegetation is presented for a contiguous area of 1.7 x 10(6) km2 in northern India, Bangladesh, and Burma. This was developed using sequential bookkeeping models, which systematically incorporate official agricultural and forest statistics with ecological, botanical, historical, geographical, and demographic data. For 149 administrative units, aggregated into 39 ecological zones, we estimated area and carbon content for each of the following land-use categories: net cultivated area, settled-built-up area, forest-woodland, interrupted woods, grass-shrub complexes, barren-sparsely vegetated areas, wetlands, and surface water. Dominant patterns of land-use change were deforestation, agricultural expansion, and wetland clearance, but significant regional and temporal disparities were observed. For the entire study region, the estimated standing stock of carbon in biomass declined by 2.62 Gt over the century. Release by periods was 911 Mt for 1880-1920, 750 Mt for 1920-1950, and 964 Mt for 1950-1980. Forest-woodland and interrupted woods vegetation released carbon equivalent to over 90% of the total release. Both conversion of forest to other vegetation types and reduction over time of biomass within vegetation types contributed significantly to decreases in total standing carbon stock during the period.