Spatial Distribution of Soil Carbon and Nitrogen Stocks in Mangrove Wetland of Xiandao Park and Shajing in Guangxi

Abstract:

The contents and storage patterns of soil organic carbon (SOC) and total nitrogen (TN), spatial distribution characteristics of SOC and TN, C/N ratios, and correlation between SOC and TN in Xiandao Park and Shajing (Guangxi) mangrove wetlands were assessed. The average SOC and TN contents of the Xiandao Park mangrove wetlands were 24.5 and 1.06 g/kg, respectively, and those of the Shajing mangrove wetlands were 11.9 and 0.71 g/kg, respectively. SOC storage capacities of the Xiandao Park and Shajing mangrove wetlands were 181.03 and 92.4 t/hm2, respectively, and were significantly different (P<0.05). TN storage capacities of Xiandao Park and Shajing mangrove wetlands were 8.23 and 5.12 t/hm2, respectively. The highest-to-lowest vertical distribution of SOC storage at both sites and TN storage at Xiandao Park was 20~40 cm > 40~60 cm > 0~20 cm, while TN storage at Shajing decreased with increasing soil depth. A significant correlation was observed between SOC and TN contents at Shajing (P<0.01); the correlation coefficient was 0.947. C/N ratio at both sites ranged from 16.77 to 24.39, indicating that the organic matter came primarily from the land. A significant correlation between soil C/N and SOC storage was evident at Xiandao Park (P<0.01), and a significant negative correlation between C/N and TN storage was evident at Shajing (P<0.05). The SOC storage of the Xiandao Park mangrove wetlands was higher than that of Chinese forests, indicating that mangrove soil has a higher carbon sequestration capacity.