Japan's National Institute for Environmental Studies (NIES) on September 28, 2011, released the results of research on the carbon balance of tropical forests in Southeast Asia. NIES jointly conducted the research with Kyoto University, Forest Research Institute Malaysia, and the Department of National Park, Wildlife and Plant Conservation in Thailand, and developed a process-based terrestrial biogeochemical model, VISIT (Vegetation Integrative Simulator for Trace gases). VISIT has been used to analyze carbon balance, carbon emissions resulting from deforestation, and changes to carbon balances caused by the conversion of forests to oil palm plantations.
The results showed that the amount of carbon emissions generated by deforestation significantly varied depending on the amount of residual woody debris that is left in the forest ecosystem. VISIT model simulations estimated the carbon stock of a 30-year-old oil palm plantation developed on deforested land to be 35% that of a forest, demonstrating a substantial difference in carbon-fixing capacity between oil palm plantations and forests.
In reviewing the predictive accuracy of the VISIT model by comparing the calculation results provided by the model with field data showed that the model accurately simulated the carbon balance of a tropical forest in Malaysia, while it tended to underestimate the carbon stock of a tropical seasonal forest in Thailand. These findings are expected to contribute to assessments of international global warming initiatives such as REDD (Reducing Emissions from Deforestation and Forest Degradation).