Articles | Volume 8, issue 9
Biogeosciences, 8, 2635–2647, 2011
Biogeosciences, 8, 2635–2647, 2011

Research article 20 Sep 2011

Research article | 20 Sep 2011

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

M. Adachi1, A. Ito1, A. Ishida2, W. R. Kadir3, P. Ladpala4, and Y. Yamagata1 M. Adachi et al.
  • 1Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa Tsukuba, Ibaraki 305-8506, Japan
  • 2Center for Ecological Research, Kyoto University 509-3-2 Hirano Otsu, Shiga 520-2113, Japan
  • 3Forest Research Institute Malaysia, 52109 Kepong, Selangor Darul Ehsan, Malaysia
  • 4Department of National Park, Wildlife and Plant Conservation, Chatuchak, Bangkok 10900, Thailand

Abstract. More reliable estimates of the carbon (C) stock within forest ecosystems and C emission induced by deforestation are urgently needed to mitigate the effects of emissions on climate change. A process-based terrestrial biogeochemical model (VISIT) was applied to tropical primary forests of two types (a seasonal dry forest in Thailand and a rainforest in Malaysia) and one agro-forest (an oil palm plantation in Malaysia) to estimate the C budget of tropical ecosystems in Southeast Asia, including the impacts of land-use conversion. The observed aboveground biomass in the seasonal dry tropical forest in Thailand (226.3 t C ha−1) and the rainforest in Malaysia (201.5 t C ha−1) indicate that tropical forests of Southeast Asia are among the most C-abundant ecosystems in the world. The model simulation results in rainforests were consistent with field data, except for the NEP, however, the VISIT model tended to underestimate C budget and stock in 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−1 in the two primary forests, whereas the model slightly underestimated GPP (26.5–34.5 t C ha−1 yr−1). The VISIT model appropriately captured the impacts of disturbances such as deforestation and land-use conversions on the C budget. Results of sensitivity analysis showed that the proportion of remaining residual debris was a key parameter determining the soil C budget after the deforestation event. According to the model simulation, the total C stock (total biomass and soil C) of the oil palm plantation was about 35% of the rainforest's C stock at 30 yr following initiation of the plantation. However, there were few field data of C budget and stock, especially in oil palm plantation. The C budget of each ecosystem must be evaluated over the long term using both the model simulations and observations to understand the effects of climate and land-use conversion on C budgets in tropical forest ecosystems.

Final-revised paper