影响广东黑石顶树附生苔藓分布的环境因子

通过对广东省黑石顶自然保护区内5个2500 m2样地内树附生苔藓的调查及有关环境因子的测定,研究了树附生苔藓的分布格局及其与环境因子的关系.树附生苔藓在不同高度的分布存在一定梯度,20 cm高处树附生苔藓的种类数与盖度均大于60 cm及更高处,且其群落优势种的数量组成与后者存在较大差异.不同树种附生苔藓盖度和种数差异较大.基于附生苔藓植物的盖度进行DCA排序及聚类分析将树种分成四组,马尾松(Pinus massoniana)因具有两种特有的网藓(巴西网藓Syrrhopodon prolifer和鞘刺网藓S.armatus)单独一组,福建青冈(Quercus chungii)亦与其余各种的差异均较大,形成一组,其余阔叶树种根据其所处的森林类型分成两组,针阔叶混交林内的阔叶树种和次生阔叶林内的阔叶树种各形成一组.对环境因子及树皮含水量和pH的分析显示,垂直梯度上空气湿度的差异可能是造成附生苔藓在不同高度分布差异的主要影响因子之一,不同树种附生苔藓的差异在一定程度上受树皮pH的影响,而与树皮含水量无关.同一树种上树附生苔藓的分布又在一定程度上受森林类型的影响.

Analysis of environmental factors affecting the distribution of epiphytic bryophyte at Heishiding Nature Reserve, Guangdong Province

We examined the distribution pattern of epiphytic bryophyte communities in different forest types and their relationship with environmental factors based on the study of bryophytes and environmental factors of five 2500 m2 plots at Heishiding Nature Reserve, Guangdong Province, China. Distribution of epiphytic bryophytes showed a vertical gradient along different tree heights: epiphytic bryophyte cover and species richness at the height of 20 cm was much greater than those at 60 cm and higher tree heights; quantitative species composition of the former differed greatly from the latter. Moreover, bryophyte cover and species richness differed greatly among tree species. Tree species were classified into 4 groups according to dentrended correspondence analysis (DCA) and cluster analysis based on epiphytic bryophyte cover. Pinus massoniana, with two dominant epiphytic species of Syrrhopodon (S. prolifer and S. armatus) specific to it, was classified to one group. Quercus chungii, also quite different to other tree species, was classified to one group alone. Other broadleaved trees were classified into two groups according to the forest type that they live in. Trees in needle-broadleaved forest were classified to one group and trees in secondary broadleaved forest to another group. According to the analysis of environmental factors and bark characteristics, for epiphytic bryophytes atmospheric humidity gradient might be one of the major factors that affects the vertical distribution, and bark pH might be an explanation for the difference in the epiphytic cover among tree species, but bark water content has no relation to the distribution pattern. Finally, community structure of epiphytic bryophytes on the same tree species is also affected by forest types.