Xin, K.; Xie, Z.; Zhong, C.; Sheng, N.; Gao, C., and Xiao, X., 0000. Damage caused by Sphaeroma to mangrove forests in Hainan, Dongzhaigang, China.
Sphaeroma population expansion has become a serious threat to mangroves in China over recent years. This study investigated the distribution of Sphaeroma damaged forests in Hainan, Dongzhaigang, China, using RS data and field investigations. The damage to mangroves caused by Sphaeroma was categorized into three grades that were based on the death rate, damage rate, and recovery rate after a typhoon. The grades were seriously damaged forest, moderately damaged forest, and slightly damaged forest, and 8.18, 230.11, and 125.83 hm2 were covered by the three grades, respectively. The most seriously damaged mangrove species were Bruguiera sexangula, Avicennia marina, and Bruguiera gymnorrhiza. However, many other mangrove species, such as Lumnitzera racemosa, Excoecaria agallocha, and Ceriops tagal, were nearly free from Sphaeroma. The integrated disaster index results, which were based on 59 different mangrove communities in the study area, showed that the communities mainly comprised B. sexangula and Bruguieras. var. rhinochopetala, Sonneratia caseolaris, and Sonneratia apetala. The B. sexangula and B. gymnorrhiza and the Kandelia obovata communities were more seriously damaged than other communities. The distribution characteristics of the damaged mangroves indicated that communities that contained larger individuals and were closer to tidal creeks were more likely to be destroyed. Finally, the impacts of aquaculture sewage and duck farming may be driving Sphaeroma population expansion, and the results strongly suggested that dynamic monitoring of the Sphaeroma population after a typhoon should occur.