Lessons from A Degradation of Planted Kandelia obovata Mangrove Forest in the Pearl River Estuary, China

Kandelia obovata (S., L.) Yong and Sonneratia caseolaris (L.) Engl. are two dominant mangrove species in the subtropical coastlines of the Pearl River Estuary, China. The main aim of this study was to investigate the specific causes of K. obovata mortality versus S. caseolaris vitality on the west coast of Bao’an, Shenzhen, China and to propose sustainable management strategies for mangrove protection and future ecological planting restoration. Results showed that although both mangroves possessed simple and unstable community structures, S. caseolaris had a more tenacious vitality than the native species K. obovata, indicating that the former possesses stronger adaptability under adversity conditions. Moreover, the salinity of the seawater collection point 5 from the K. obovata plot was found to be lower than that of seawater collection point 1–3 from the S. caseolaris sample plots, indicating that no hydrologic connectivity existed in the K. obovata plots. In addition, the location of the drain outlet (seawater collection point 8) might be another potential risk factor for the dead of near K. obovata forests, implying that they were badly affected by poor oxygen and serious inorganic pollution, such as ammonium nitrogen, total phosphorus, and other inorganic substances. Depending on local circumstances, we should consider strengthening infrastructure construction to activate hydrological connectivity, reinforcing the stability of man-made mangrove communities, and controlling the pollution sources for sustainable mangrove protection and management on the western coast of Bao’an, Shenzhen, China.