Tropical peat forests of the Asian-Pacific contain among the largest terrestrial C pools on Earth, provide livelihoods for millions of people, and are reservoirs of unique array of biological diversity. Despite their intrinsic values, peat forests are being degraded or deforested at alarming rates due to a myriad of causes including drainage, conversion to agriculture, and associated fires. An estimated 45% of peat forests have been deforested or drained, thus creating a shift in their function from globally significant C sinks to globally significant sources of CO2 emissions. Yet, remarkably few field studies have empirically quantified C pools of peat forests of the Asian-Pacific, particularly how these pools vary spatially and by vegetation type. In order to understand their contribution to global CO2 emssions as well as their value in C financing strategies aimed at mitigating climate change (e.g., Reduced Emissions from Deforestation and Degradation (REDD+)), quantification of peat forest C pools and their components is needed. We quantified ecosystem C pools (belowground and aboveground) of 5 peat forests in Tanjung Puting National Park (TPNP), Central Kalimantan, Indonesia (Southern Borneo), and 5 forests on the Island of Kosrae, Micronesia.
Results/Conclusions Peat depths in Kosrae were as deep as 5.8 m with a mean of 3.3 m. Peat layers of the sampled riverine peat forests of Tanjung Putting NP were shallow (<1m) relative to those sampled in Kosrae but very indicative of peat forests of riverine environments and those potentially most subject to human perturbations. Relative to upland tropical forests, ecosystem C pools were remarkably high, exceeding 1000 Mg/ha in TPNP stands and >2000 Mg/ha in Kosrae stands. The most abundant ecosystem C pool was that of the peat layers. Total aboveground biomass of tropical peat forests ranged from 256 to 472 Mg/ha (to 219 Mg C/ha). Even though peat layers in all sampled forests at TPNP were less than 1 m, total belowground C pools were high, ranging from 354 to 994 Mg/ha. Our measurements of ecosystem pools in Kalimantan should be viewed with the consideration that an estimated 58% of peat forests have depths <2 m even though peat thickness of tropical peat forests may reach 20 m (with an average thickness of 2 to 5 m). Additional studies of ecosystem C pools of undisturbed peat forests and their fates following land cover change are needed in order to better quantify C emissions from deforestation.
