Carbon budget of tropical forests in Southeast Asia and the effects of deforestation: an approach using a process-based model and field measurements

摘要

More reliable estimates of the carbon (C) stock within forest ecosystems andC emission induced by deforestation are urgently needed to mitigate theeffects of emissions on climate change. A process-based terrestrialbiogeochemical model (VISIT) was applied to tropical primary forests of twotypes (a seasonal dry forest in Thailand and a rainforest in Malaysia) andone agro-forest (an oil palm plantation in Malaysia) to estimate the Cbudget of tropical ecosystems in Southeast Asia, including the impacts ofland-use conversion. The observed aboveground biomass in the seasonal drytropical forest in Thailand (226.3 t C ha?1) and the rainforest inMalaysia (201.5 t C ha?1) indicate that tropical forests of SoutheastAsia are among the most C-abundant ecosystems in the world. The modelsimulation results in rainforests were consistent with field data, except forthe NEP, however, the VISIT model tended to underestimate C budget and stockin the seasonal dry tropical forest. The gross primary production (GPP)based on field observations ranged from 32.0 to 39.6 t C ha?1 yr?1in the two primary forests, whereas the model slightly underestimated GPP(26.5–34.5 t C ha?1 yr?1). The VISIT model appropriately capturedthe impacts of disturbances such as deforestation and land-use conversionson the C budget. Results of sensitivity analysis showed that the proportionof remaining residual debris was a key parameter determining the soil Cbudget after the deforestation event. According to the model simulation, thetotal C stock (total biomass and soil C) of the oil palm plantation wasabout 35% of the rainforest's C stock at 30 yr following initiation ofthe plantation. However, there were few field data of C budget and stock,especially in oil palm plantation. The C budget of each ecosystem must beevaluated over the long term using both the model simulations andobservations to understand the effects of climate and land-use conversion onC budgets in tropical forest ecosystems.