The Effect of Deforestation on Regional Terrestrial Carbon Balance : A Case Study of Kalimantan Island <Articles>

Rainforests play an important role in the inter-relationship of biosphere-atmosphere in the global and regional scale as one of the largest carbon storages in terrestrial ecosystem. Nowadays, rainforests are subjected to serious threats mainly due to human activities, such those occurring in Borneo Island, where the rapid land use changes in the last few decades may result in imbalance of natural carbon cycle and may lead to more intense environmental problems. As a regional dynamic vegetation model, the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ-DGVM) is modified in this study to include the land use change aspect in the tropical forests. To analyze the effects of land use changes in Borneo Island, two scenarios are applied: without and with land use change scenario. Simulation results show that the increase in average Net Primary Production (NPP) over Borneo Island from 1960 to 2002 for each scenario is 2.44 GtC/year and 2.69 GtC/year, respectively. While the increase in heterotrophic respiration is 0.91 GtC/year and 2.41 GtC/year, respectively. If carbon losses by harvesting are included, the later scenario shows that the rate of carbon loss from 1960 to 2002 is 471.9 gC/m2/year. As a result, more than 50% of terrestrial vegetation's carbon was taken away from Borneo Island during that period. In future, as compared to NPP, heterotrophic respiration tends to increase with higher rates and may lead to the change of Borneo Island's role from carbon sink to carbon source