South America: a reservoir of continental carbon - first estimate of changes since 18,000 yr BP

Resumo

By using geographic and palaeogeographic sketches established for the present situation (before recent deforestation) and for the glacial maximum (about 15,000-18,000 BP) we can estimate the possible total biomass (phytomass) of the South American continent. According to the biomass density used in this first estimate for ten major ecosystems, the results show a possible increase from 140 Gt of carbon (glacial maximum) to 214 Gt C (preindustrial) for the phytomass, and 120 to 180 Gt C for the soils. These preliminary results are possibly only a 60 or 70 percent approximate estimate and could be modified with computation using other palaeogeographic models or another biomass density. It is therefore to underline the urgent need of more field biomass measurements, ecosystems mappings, and palaeostudies to evaluate the part of South America as a future possible sink for the atmospheric carbon dioxide. The Amazonian forest makes of South America an important continental reservoir of carbon for the planet Earth. This continent represents consequently a key zone for the research and knowledge of changes in the biogeochemical cycle of carbon. In order to evaluate more precisely the role it plays we estimated the approximate quantities of carbon in the total phytomass and the carbon in soils for each of the ecosystems represented in Figure 1, both for Present and Last Glacial Maximum landscapes.