高海拔区云杉林皆伐迹地早期自然恢复进程中苔藓组成与发育程度评估

Evaluation of species composition and development of bryophyte community during early natural recovery progress of high-altitude spruce cutovers

为评估皆伐迹地地表苔藓组成与特点,同时为苔藓生物多样性的保护与恢复提供理论依据,作者于2006年7–10月调查了四川省阿坝藏族羌族自治州地区壤塘二林场云杉(Picealikiangensis var.rubescens)林皆伐迹地自然恢复过程中苔藓植物和维管植物的组成和结构;采用方差分析法对苔藓层结构参数进行差异性检验,对苔藓层结构参数和环境因子作非参数Spearman相关性分析,并对显著性因子进行回归分析。结果表明:(1)在9–27年植被自然恢复过程中,不同阶段苔藓植物群落优势物种组成发生了更替。一些个体较小、易产生孢子、喜阳、抗干扰的顶蒴藓物种侵入并占据优势;而一些出现于早期采伐迹地、喜湿、对环境变化较敏感的侧蒴藓物种消失。(2)随着迹地植被自然恢复,苔藓植物群落物种丰富度、多样性指数和均匀度指数总体上呈下降趋势;迹地上样方间苔藓层盖度和生物量波动较大,但随着自然恢复进程而迅速减少,群落结构趋向简单化;(3)维管植物发育程度与苔藓层发育关系密切;草本层生物量对苔藓盖度和种丰富度起主导作用,草本层高度是对苔藓生物量有显著影响的主导因子。综合分析表明,早期采伐迹地的自然恢复进程中由维管植物群落结构变化导致的生境差异对苔藓植物发育影响较大。

Due to traditional forest management, many forest ecosystems in western Sichuan Province have become degraded. To quantify the composition and structure of bryophyte communities which are early in the natural recovery process, we sampled four sites with similar topographic situation, but at different points in the recovery process. All sites were located in the Rangtang County, Aba region, Sichuan Province. Species composition and structural parameters were surveyed between July and October of 2006. We used ANOVA analysis to detect differences among bryophyte communities, and nonparametric Spearman correlation to test for relationships between bryophyte structural parameters and environmental factors. We used regression analysis to explore the factors influencing bryophyte development. Our results suggested three main points. Firstly, dominant species composition changed during the natural recovery process. Some small-sized, heliophilous, and disturbance-resistant acrocarpous mosses with a high sporulation ability had expanded their populations, while some hygrophilous pleurocarpous mosses sensitive to early successional conditions had disappeared. Secondly, diversity indices, coverage, and biomass decreased during the natural recovery proc- ess, indicating that bryophyte communities became simplified with recovery progress. Thirdly, there was a close relationship between vascular plants and bryophytes. Bryophyte cover and richness were mainly influenced by herbaceous layer biomass, while bryophyte biomass was significantly affected by herbaceous layer height. Our results implied that different microhabitats resulting from vascular plant community development affected development ofbryophyte communities.