干旱区生态环境知识资源中心

Soil organic carbon contents and their vertical distributions were studied in two natural saline-alkalined wetlands (Erbaifangzi and Fulaowenpao) with different hydrological conditions in Xianghai National Nature Reserve of Northeast China in 2001. Soil properties such as total nitrogen, TF, soil pH, C/N, soil particle size, and bulk densities were also analyzed in order to identify their relationships to soil organic carbon density (SOCD). Results showed that mean SOCD of EBFZ from 30 soil profiles was 8.23 +/- 1.40 kg C m(-2), higher by about 41 % than that of FLWP, but both of them were much lower by 43% to 92% than those in other wetlands in China. Soil organic carbon generally decreased with depth in soil profiles and was mainly stored in the upper 30 cm (11.82 in), accounting for more than 50% of the total. Soil organic carbon density was positively significantly correlated with soil organic matter, total nitrogen, total phosphorus, and clay contents (p < 0.001) and was negatively significantly correlated with sand contents (p < 0.001). There was also a significant correlation between SOCD and soil pH or silt contents at the level of p < 0.01. Hydrological regime could impact carbon storage in wetland soils, and water deficit would lead to carbon loss. Ecological water supplement might be necessary to mitigate water shortage and increase carbon storage of wetlands in semi-arid and arid regions.