海堤对广西沿海红树林的数量、群落特征和恢复的影响

Effect of sea dike on the quantity, community characteristics and restoration of mangrove forest along Guangxi coast.

广西大陆海岸线的 63%为海堤 ,海堤数量达 498个 .海堤建立毁灭了原生红树林 ,现余 5654hm2 ,其中约 85%为堤前红树林 .海堤阻截了红树林滩涂的自然海岸地貌 ,结果是红海榄和木榄已很少 ,榄李濒危 ,角果木已消失 ,海漆和陆岸种类只能沿海堤坡面生长 ,而先锋红树植物白骨壤和桐花树成为现有红树林的优势种 .堤前红树林的恢复受到海堤维护时强烈的人为干扰 .堤前滩涂相对于平均海平面的高程较低 ,不是红树林繁盛的理想滩涂 .红树林人工造林的成活率和次生林恢复的速率在很大程度上取决于生境的沉积率 .

of the coastline of Guangxi mainland are margined by 498 sets of sea dikes, which destroyed the pristine mangrove forests, with a remain of 5654 hm 2. About 85% of the remain are dike fringed mangrove forests. The dike discontinued the natural geomorphological profile of mangrove flat.Consequently, Rhizophora stylosa and Bruguira gymnorrhiza are sharply decreased, Lumnitzera racemosa is endangered and Ceriops tagal is disappeared. Excoecaria agallocha and other most landward species can only grow on dike slopes. In contrast, the pioneer species of Avicennia marina and Agiceras corniculatum dominate the present day mangrove forests.The restoration of sea dike fringed mangrove forests are strongly interfered by human′s maintenance of sea dikes. The tidal flats edged by sea dikes are not the optimal habitats for mangrove forest development, due to relatively low elevation above mean sea level.It seems that the survival rate of afforestation and the restoration speed of secondary mangrove forests may greatly depend on the sedimentation rate of habitats.