亚热带常绿阔叶林附生地衣凋落物的物种多样性和生物量的边缘效应

地衣是亚热带山地森林系统附生生物类群的重要组成部分之一,对环境变化极其敏感。为了更好地了解附生地衣对森林边缘效应的响应,我们在云南哀牢山地区原生山地常绿阔叶林中,分别在距林缘5m、25m、50m和 100m处设立样地,收集附生大型地衣的凋落物1年;分析附生地衣凋落物的物种多样性和生物量、功能群特征和组成结构对林缘深度变化的响应特征。研究结果显示,边缘效应能够显著提高林缘附生地衣群落的物种多样性和生物量;其发生的距离最深不超过25m。林缘-林内梯度上,不同地衣功能群的响应模式具有各自的特征。排序分析表明仅在5m样地与其他样地之间存在显著差异,指示种分析则发现仅5m样地具有指示种。哀牢山原生林中边缘效应促进林缘附生地衣生长和分布的现象,可能与当地高湿环境削减了地衣的高光损伤以及以叶状和灌状类群为主的地衣个体受到风力破坏的程度相对较低有关。

Edge effects on species diversity and biomass of epiphytic macrolichen litterfall in a subtropical evergreen broad-leaved forest

Epiphytic lichens are an important component of epiphytes and show extreme sensitivity to environmental changes in subtropical montane forests. To understand the response of epiphytic lichens to forest edge effects, 16 plots at 5m, 25m, 50m, and 100m from the edge in four edge-interior transects were established in a primary montane moist evergreen broad-leaved forest in the Ailao Mountains of Yunnan. Within each plot, epiphytic macrolichen litterfall was collected over one year and the differences in biomass, species diversity and community structure were compared. It was indicated that there was a positive effect of edge environments on the species diversity and biomass accumulation of epiphytic macrolichen litterfall in the plots within 25m from the edge. Epiphytic lichen groups also showed various responses to edge effects. Ordination analysis showed that there was a significant difference in species composition between the 5m plots and the other plots while indicator species analysis revealed significant indicators only occurred in 5m plots. The positive effect of forest edge on the epiphytic lichens in the Ailao Mountains may be due to the high-light damage largely weakened by the high humidity and the small thalli of dominant foliose and fruticose macrolichen species being potentially less prone to mechanical damage destroyed by wind-force.