Objective The aim was to explore the changing law of soil nutrients in mangrove forests in the eastern part of Guangdong.

Method Soil samples of 0 ~ 30 cm layers were collected respectively in 6 typical mangrove communities. The nutrient indices including organic matter (SOM), organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and stoichiometric ratios of soils under different community types were determined. One-way analysis of variance (ANOVA) and correlation analysis were used to analyze the differences and correlations between different communities and indices. The nemerow index method was used to comprehensively evaluate the soil fertility of different community types.

Result There were certain differences in soil nutrients among different community types, which were generally manifested as higher soil nutrient content in three community types: S. apetala + A. corniculatum + K. obovate + A. aureum, S. apetala + A. corniculatum + K. obovate + S. caseolaris, and S. apetala + S. caseolaris. The average values of the soil C∶N, C∶P, and N∶P were 18.39, 88.20 and 4.76, respectively. The average values of C∶N and C∶P were higher than the national average level, while the N∶P was lower than it. Except for the community of A. corniculatum in the study area which were susceptible to P limitation, the other 5 types were susceptible to N limitation. Soil comprehensive fertility coefficients showed a trend of S. apetala + S. caseolaris (2.08) > S. apetala + A. corniculatum + K. obovate + A. aureum (2.02) > S. apetala + A. corniculatum + K. obovate + S. caseolaris (2.01) > K. obovata (1.75) > S. apetala (1.70) > A. corniculatum (1.41), and the average coefficient of comprehensive fertility was 1.83. Correlation analysis showed that SOC and TN were highly significantly and positively correlated (P < 0.01), and there were some differences between soil nutrient indices and stoichiometric ratios under different community types.

Conclusion The comprehensive fertility level of mangrove wetland soils in the eastern part of Guangdong was relatively good. The growth of mangrove vegetation was easily limited by N. In the subsequent mangrove creation and restoration, a multi-species mixing pattern should be considered to maintain the sustainable development of mangrove forests.