Ecosystem carbon storage and partitioning in a tropical seasonal forest in Southwestern China

Abstract

Tropical forests play an important role in the global carbon cycle. Despite an increasing number of studies have addressed carbon storage in tropical forests, the regional variation in such storage remains poorly understood. Uncertainty about how much carbon is stored in tropical forests is an important limitation for regional-scale estimates of carbon fluxes and improving these estimates requires extensive field studies of both above- and belowground stocks. In order to assess the carbon pools of a tropical seasonal forest in Asia, total ecosystem carbon storage was investigated in Xishuangbanna, SW China. Averaged across three 1ha plots, the total carbon stock of the forest ecosystem was 303tCha−1. Living tree carbon stocks (both above- and belowground) ranged from 163 to 258tCha−1. The aboveground biomass C pool is comparable to the Dipterocarp forests in Sumatra but lower than those in Malaysia. The variation of C storage in the tree layer among different plots was mainly due to different densities of large trees (DBH>70cm). The contributions of the shrub layer, herb layer, woody lianas, and fine litter each accounted for 1–2tCha−1 to the total carbon stock. The mineral soil C pools (top 100cm) ranged from 84 to 102tCha−1 and the C in woody debris from 5.6 to 12.5tCha−1, representing the second and third largest C component in this ecosystem. Our results reveal that a high percentage (70%) of C is stored in biomass and less in soil in this tropical seasonal forest. This study provides an accurate estimate of the carbon pool and the partitioning of C among major components in tropical seasonal rain forest of northern tropical Asia. Results from this study will enhance our ability to evaluate the role of these forests in regional C cycles and have great implications for conservation planning.