Temporal Changes of Ecosystem Carbon Stocks in Rubber Plantations in Xishuangbanna, Southwest China

Rubber (Hevea brasiliensis) plantations have been expanded rapidly in tropical regions of Southwest China and cover more than 20% of land area in Xishuangbanna. Several studies have addressed changes of soil C stocks in rubber plantations; however, estimates of total ecosystem C stocks and their temporal changes in rubber plantations have been inadequately studied. This study calculated C stocks in soil, biomass, litter, and dry rubber (latex), and estimated the total ecosystem C stocks of rubber plantations in an age sequence of 3-, 7-, 9-, 21-, 27-, and 34-year-old in Xishuangbanna, Southwest China. The total C stocks in rubber plantations ranged from 150.3 to 283.7 Mg C ha−1, with a mean of 213.4 Mg C ha−1. The plantations ≤ 9-year-old had significantly lower (P < 0.05) total C stocks than those older than 9 years. Carbon stocks in soil (mass equivalent) were between 107.1-170.5 Mg C ha−1 and in living biomass were between 2.8-95.7 Mg C ha−1, representing the largest and the second largest C components in a rubber plantation ecosystem. Neglect of dry rubber C stock resulted in an underestimate of 7.8%-14.2% of the total C stock in the rubber plantations older than 9 years, which was much larger than the contribution of litter C stock (less than 2%).