Land use change and net C flux in Indian forests

This paper reports on the net carbon flux caused by deforestation and afforestation in India over the period from 1982 to 2002, separately for two time periods, 1982-1992 (PI) and 1992-2002 (PII), using the IPCC 2006 guidelines for greenhouse gas inventories. The approach accounts for forest and soil C pool changes for (a) forest areas remaining as forests, (b) afforested areas and (c) deforested areas. The data set used were remote sensing based forest cover for three time periods (1982, 1992, 2002), biomass increments, biomass expansion factors and wood density. In addition a number of required coefficients and parameters from published literature were adopted. In the 1982-2002 period, the forest cover changed from 64.20 Mha in 1982 to 63.96 and 67.83 Mha in 1992 and 2002 respectively. During the PI and PII periods, plantations were also established of 0.2 and 0.5 Mha yr(-1), while the annual deforestation rate was about 0.22 and 0.07 Mha in these periods, respectively. The average net flux of carbon attributable to land use change decreased from a source level of 5.65 Tg C yr(-1) (or 0.09 Mg C ha(-1) yr(-1)) during PI (1982-1992) to a sink level of 1.09 Tg C yr(-1) (or 0.02 Mg C ha(-1) yr(-1)) during PII (1992-2002). Over recent years, Indian forests have acted as a small carbon sink. The results indicate that the conversion of land to forest (regeneration/afforestation) led to a net uptake of 0.86 and 1.85 Tg C yr(-1) in PI and PII, respectively. By contrast, the net C emissions from the forest land conversion to another land use (deforestation) resulted in annual emissions of 9.9 and 3.2 Tg C during PI and PII, respectively. The cumulative net carbon flux from Indian forests due to land use change between 1982 and 2002 was estimated as 45.9 Tg C. The largest fluxes result from the conversion of forest land to cropland and waste lands, and since there are uncertainties in input variables (due to very large spatial heterogeneity) that affect net C flux from land use change, there is an urgent need for more reliable district-based data to facilitate accurate and refined estimates in future. This study was intended to improve consistency and completeness in the estimation and reporting of greenhouse gas emissions and removals. (C) 2009 Elsevier B.V. All rights reserved.