Spatial patterns and environmental factors of rapidly degraded mangroves at Dongzhaigang Harbor in Hainan

Objective The purpose of this study was to analyze mangrove degradation in some coastlandsof southern China.

Method  Mangrove of Dongzhaigang Harbor in Hainan Province was investigated as acase study. Landscape pattern dynamics of mangrove wetland from 1987 to 2013 were analyzed at Dongzhaigang Harbor by interpreting five phase remote sensing images. The degradation characteristics of mangrove forest and its spatial patterns were also further studied using SPOT5 and aerial imagery. Furthermore, the influencing factors of mangrove degradation such as topographical factors and terrestrial contaminant loading were analyzed by surveying numerous sampling plots.

Result and conclusion  It was foundthat mangrove area decreased from 1 709.4 hm² in 1999 to 1 679.5 hm² in 2013, while the area of pondsin the 2 km coastal buffers increased from 59.1 hm² in 1987 to 1 986.9 hm² in 2013. The dead area ofmangrove patches had reached 4 hm² by the end of 2013. Spatially, mangrove degradation mainly locatedin low-lying land and both sides of contaminant transport channels. The degradation degree of River-typemangrove communities was the most serious, whose major distribution was in the middle and lower reaches of Yanfengdong River. Meanwhile, the degraded mangrove communities also distributed sporadicallyin frontier areas of Dongzhaigang Harbor. The degradation degree was higher for mangrove communities inthe climax stage of succession. The distribution of degraded mangrove communities was mainly determined by terrestrial pollutant loading.