人工无瓣海桑林下灌层分布格局及多样性研究

Distribution Pattern and Diversity of Shrub Layer under the Artificial Sonneratia apetala Forest Community

以雷州附城镇无瓣海桑人工林为对象,采取目标树中心样圆法,运用Simpson指数、Margalef丰富度指数、Pielou均匀度指数以及Poisson分布与T检验分析无瓣海桑对乡土红树植物的多样性和分布格局的影响。结果表明:引进无瓣海桑后,秋茄、桐花树、红海榄、木榄和白骨壤这几种乡土红树植物在无瓣海桑林下逐步适应生长,无瓣海桑林缘灌木层物种多样性指数比林内更高,各类圆形样方中物种的Pielou均匀度指数和Simpson指数均没有显著差异,而Margalef丰富度指数的差异达显著水平(P<0.05);同一物种在不同林龄的无瓣海桑林下的分布格局不同;白骨壤、红海榄、秋茄、桐花树和木榄在无瓣海桑林下呈集群分布,其强度为木榄>桐花树>秋茄>白骨壤>红海榄;引种无瓣海桑林下未发现无瓣海桑幼苗,表明在该研究地无瓣海桑难以天然更新成林,对乡土红树植物的天然更新成林和扩散未产生影响。

Taking Sonneratia apetala plantation in Fucheng Town of Leizhou City as research objects,adopting survey method of circular sample of target tree,the effects of Sonneratia apetala on diversity&distribution pattern of local native mangrove were analyzed by using the Simpson index,Margalef richness index,Pielou evenness index and Poisson distribution&t-test.Result shows that:After the introduction of Sonneratia apetala,the native mangrove plants such as Kandelia cande,Aegiceras corniculatum,R.stylosa,Bruguiera gymnorhiza,Avicennia marina have gradually adapted to grow in the environment of Sonneratia apetala.Diversity index is higher than in forest,while the Margalef index was significantly different(p<0.05)among different stand types;the Poisson distribution V/m&t-test show that A.marina,R.stylosa,K.candel,A.corniculatum&B.gymnorhiza were cluster distribution under the forest of S.apetala.The strength of the cluster distribution is B.gymnorhiza>A.corniculatum>K.candel Druce>A.marina>R.stylosa.The natural recruitment of S.apetala in this research area is extremely difficult,and it has no effect on the natural recruitment&dispersal of native mangrove plants.