CARBON SEQUESTRATION IN RUBBER TREE PLANTATIONS ESTABLISHED ON FORMER ARABLE LANDS IN XISHUANGBANNA, SW CHINA

The ability for vegetation and soil organic matter (SOM) to sequester atmospheric CO2 has received a lot of attention recently. Two management options being considered for enhancing C sequestration from the atmosphere include tropical forest conservation and establishment of plantations; however, there is still considerable debate regarding the appropriateness of using plantations and the sequestration potential of tropical plantations. There are 1.3×10^5 hm^2 of rubber trees (Hevea brasiliensis) plantations in Xishuangbanna, southwest China, which account for approximately 14% of the forest lands in this region. In this study, eleven plantations of different ages were selected to investigate C sequestration in the vegetation arid soils following the establishment of rubber tree plantations on former arable lands. The results indicated that the average biomass growth rates of the rubber trees, calculated according to two different biomass growth equations, were 10.2×10^3 and 9.4×10^3 kg t C hm^(-2)•a^(-1). Soil C stocks in the top 40cm and 1 m of soil increased at rates of 0.61×10^3 and 0.72×10^3 kg t C hm^(-2)•a^(-1), respectively. In total, C sequestration was approximately 5.82×10^3 to 5.42×10^3 kg t C hm^(-2)•a^(-1) in the vegetation and soil as calculated by the two biomass growth models. When comparing the two models, our results showed that the biomass calculated based on the equation of Tang et al. was higher than that based on the equation of Brown, especially in young- and middle-aged rubber tree plantations.