CONICET | Buscador de Institutos y Recursos Humanos

Forest biomes are major reserves for terrestrial carbon and major components of global primary productivity. Many factors determining carbon fluxes in forests are influenced by land management practices and any shift in the magnitude of these processes may have a large impact on the global carbon balance. In Argentina, a continuous conversion of forest areas into agriculture has been reported in the last years. Land-cover types may be accurately documented from remote sensing and combined with carbon inventories to estimate regional carbon stocks. The aim of this study was to estimate changes in the aboveground carbon stocks between 1979 and 2004 in the Dry Chaco forest of central Argentina. We used Landsat TM images to map five widespread land-cover types and the most detailed field-based carbon inventory for each land-cover type up to now. The study area comprises about 1.4 Mha of the southern edge of the Gran Chaco, storing 32 Tg C at 2004. During the study period, the most important land-cover change was a decrease of 15% of the forest cover, an increase of 9.3% of open shrubland cover and a raise of 7% of agriculture areas, resulting in a net carbon loss of 0.31 Tg C y-1. The main cause of aboveground carbon loss was total deforestation for agriculture, representing a carbon loss of 0.26 Tg C y-1; forest degradation, due to the combined effect of deforestation and overgrazing, represented a carbon loss of 0.13 Tg C y-1 and selective logging resulted in a carbon loss of 0.14 Tg C y-1. Forest regrowth, not considered in previous studies, appeared as significant carbon gain of 0.23 Tg C y-1. If the process of forest replacement is still perceived as economically profitable in Argentina, large areas of Chaco forest will be cleared with large impacts on regional carbon stocks.