康禾自然保护区森林苔藓植物丰富度对地形因子的响应

Responses of Forest Bryophyte Richness to Topographic Factors in Kanghe Nature Reserve, Guangdong Province

为揭示森林苔藓植物分布和丰富度对地形因子的响应,在广东东部康禾保护区内设置6 hm^2样地调查苔藓植物及坡向、坡度和凹凸度等地形因子,分析地形因子与苔藓植物丰富度的关联及不同地形梯度下苔藓植物群落组成和物种丰富度的差异。样地内共记录到苔藓植物25科36属47种(含3变种),其中苔类15种,藓类32种。多响应置换过程分析表明,不同的坡度和坡向分组中苔藓植物群落组成不存在显著差异,而在不同凹凸度间的群落物种组成则存在显著差异。Kruskal-Wallis非参数的方差检验及相关性分析则表明,坡向和坡度对苔藓植物丰富度的影响不存在显著的梯度效应,而凹凸度不仅与苔藓植物丰富度表现出显著的线性相关,而且还存在显著的强梯度效应,表现为随凹凸度的增大苔藓植物丰富度呈显著下降的趋势。苔类和藓类对地形因子的响应各不相同。与坡向相关的潜在直射光入射辐射(PDIR)对苔类植物丰富度的影响强于对藓类植物丰富度;而凹凸度对苔类和藓类植物的分布和丰富度变化均有显著的影响,且呈现很强的梯度效应。这些结果反映出苔类植物丰富度对与坡向相关的热量变化较为敏感,而无论是苔类还是藓类植物均对与水分条件相关的凹凸度变化敏感。本项研究揭示了森林苔藓植物分布和丰富度对地形因子的响应,可为区域生物多样性保护和苔藓植物相关的生态学研究提供重要的参考。

In order to reveal the distribution of forest bryophytes and their responses to topographic factors, we set up 6-hm^2 plots in Kanghe Nature Reserve, east Guangdong, to conduct bryophyte census and measure topographic factors, i.e., aspect, slope steepness, and convexity. We analyzed the association between the topographic factors and bryophyte species richness, and tested for significant difference in bryophyte species richness across topographic gradients. A total of 47 bryophyte species(including 3 varieties) from 25 families and 36 genera were recorded in the sampling plots, of which 15 species were liverworts and 32 mosses. The multi-response permutation procedures(MRPP) indicated that bryophyte species composition did not significantly differ under various aspect and slope steepness classes. The nonparametric analysis of variance using Kruskal-Wallis test together with correlation analysis showed no significant gradient effects in aspect and slope steepness on bryophyte species richness, but significant linear correlation between convexity and bryophyte species richness, as well as a strong gradient effect in convexity. Bryophyte species richness significantly decreased with the increase of convexity. Liverworts and mosses varied in their responses to topographic factors. The aspect-related potential direct incident radiation(PDIR) had a greater effect on liverwort species richness than on moss species richness, while convexity had significant influences on the distribution and species richness of both liverworts and mosses with a strong gradient effect. These findings demonstrated that the liverwort species richness was sensitive to the aspect-related thermal energy change, while both liverwort and moss species richness was sensitive to moisture-related convexity variations. Our study has revealed the distribution of forest bryophytes and their responses to topographic factors, and will provide baseline reference for regional biodiversity conservation as well as ecological studies that are related to bryophytes.