THE Law for Vertical Structure and Succession Dynamics of Mangrove in Qinglan Harbour, Hainan Island

Under better condition of protection the mangrove communities in Qinglan Harbour present two-layer structures of tree and shrub, in which tree layer is 4～8 m and shrub layer is 0.4～1.2 m in height.The biomass of stauding trees above ground decreases with the increase of tree height i.e. 50% in 0～2m,40.3% in 2～4m,7% in beyond 4 m. It was known from the investigation that after the mangrove communities were destroyed and interfered by human beings, they are decreased by 1611 hm2,in the period of 27 years,and turned into brushes with only one layer structure,which is lower in biomass and productivity only 9.6～14.3 t/hm2 and 1.1～2.0 t/(hm2·a)respectively. The study indicated that the biomass and net productivity of Bruguiera gymnorhiza stand were 91.5 t/hm2, and 4.7 t/(hm2·a), and they will increase to 350.7 t/hm2 and 13.5 t/(hm2·a)in the end of the coming six years.