环境因子对湖泊岛屿苔藓植物分布和物种组成的影响

Environmental variables affect species composition and distribution of Bryophytes

苔藓植物对环境有很强的敏感性,且具有广泛的适应性和强大的繁殖能力,在生态环境监测和生态恢复上具有重要作用。通过野外样地调查方法,回归分析和典范对应分析(CCA)探索了环境因子对物种分布和组成的影响,偏CCA计算了各环境因子对物种组成的总效应和净效应。结果表明:苔藓植物种类及物种组成相似性随着岛屿面积和岛屿海拔高度的增大而极显著的增大,随岛屿形状指数和岛屿离陆地最近距离的增大而显著的减小;8个环境因子共解释了物种组成变异的35.6%,其中基质、坡度、草本盖度、坡向、乔灌层郁闭度、人为干扰、空气湿度和海拔对物种组成的净效应达到显著水平(P<0.05),但其作用强度依次减小;美灰藓Eurohypnum leptothallum是最优势种,受环境因素小,它在其发生的77.7%取样样方中盖度达到19.2%。

Bryophytes are sensitivity to the changes in the environment, exhibit high degree of adaptability and ability to reproduce, and play an important role as bioagents in monitoring of the ecological environment and ecological restoration. In the present study, the relationship between species composition and environment variables was elucidated by the canonical correspondence analysis （CCA）, regression analysis and Hongfeng river field survey. Partial CCA was used to calculate the gross and net effects on species richness to each environmental variable. The number of bryophytes and composition similarity of species increased along with the increasing area and height of islands （Yejipo, Gantianbian Island1, Xinzhuang Island1, Hongfeng river island1, Yuanyang island1, Yuanyang island2, Hongfeng river island2, Xinzhuang island2 and Ganbiantian island2 with less human disturbance） but declined with increasing island shape index and the closest distance of island from land. Eight environmental variables totally explained 35.6% of total variation in species composition, of which the net effects of matrix, slope, herbcov, aspect, canopy, human disturbance, moisture and altitude on species composition were significant （P〈0.05）, however, the intensity of their effect decreased successively. Eurohypnum leptothallum is the most dominate species with little impact from environment, emerge in 77.7% of samples and coverage of at least 19.2%.