Carbon sequestration in paddy ecosystems in subtropical China

摘要

Carbon (C) sequestration in paddy soils was studied in 4 selected landscape units as representatives for the lowland (LL), low-hill (LH), high-hill (HH) and karst-mountain (KM) areas in subtropical China. The mean values for organic C content in paddysoils (0-20cm) in the landscape unit varied from 16.0 to 27.7 g /kg, which were remarkably larger than those for soils under arable cropping and orchard, and even under woodland except in the KM landscape unit. In the LH landscape unit, the mean organicC content in paddy soils increased by 1.67 times (P<0.01) in the period of 1979-2003. This increase was concordant with the prolonged increase (since 1950s) in rice productivity in the region. It is concluded that paddy ecosystems in subtropical China had the ability to sequester organic C in amounts larger than those in other ecosystems. As these landscape units represent the real situations for paddy ecosystems under farmers' practices for rice production, data from this study confirm that the trendof continuing organic C sequestration in paddy soils occurred in subtropical China.