Above-ground carbon stocks in tropical fallows, Sarawak, Malaysia

Assessment of biomass stocks and growth rates are essential for knowledge on carbon cycle dynamics. Being a part of an agricultural system, fallows provide two services: they contribute to food security and they store carbon. In this study, 3384 trees in Sarawak, Malaysia, were measured for diameter at breast height (DBH) along a chronosequence of fallow ages, and the biomass and carbon stocks of the fallows were estimated using published allometric equations. During the first 15 years following abandonment, the biomass of the shifting cultivation fallows accumulates following a logistic model reaching saturation after 6 years at 47 Mg dry matter (DM) per hectare. Using the differential equation of the logistic model to calculate biomass accumulation rates shows very high accumulation rates (up to 12.7 Mg carbon per hectare per year) when compared to standard calculations of mean annual accumulation rates.