高海拔幼林地表苔藓组成与结构——皆伐与造林实践的影响评估

 对壤塘县二林场4个不同时间皆伐和造林后形成的幼林地, 开展了苔藓植物和维管植物多样性调查, 采用方差分析法对苔藓植物特征进 行差异性检验, 对苔藓植物结构特征和环境因子作偏相关性分析。结果表明: 1)幼林地4个阶段的发展进程中苔藓物种组成变化显著。优势种相 似, 为喜光耐旱的侧蒴藓物种; 一些耐阴喜湿的种类种群扩大成为林下局部生境优势物种; 同时由于干扰造成地表裸露后产生耐旱土生或石生 性广泛分布的藓类。2)随着幼林地植被恢复进程, 苔藓物种丰富度(22～37)和多样性指数(0.37～1.08)呈增长趋势。结构特征在4个幼林地表现 出较强的差异性。3)乔木与灌木层盖度与苔藓植物的发育呈正相关, 灌木层盖度的发育明显促进了苔藓植物丰富度的增加, 而基于喜光先锋的 禾草为主的草本发育程度很高, 与凋落物生物量一起抑制了苔藓的发育。随幼林地发展, 乔、灌、凋落物发育性质及其相互作用发生动态变化 。因此加速幼林地乔、灌层片的发育对于促进地表苔藓植物多样性的恢复与层片发育具有重要作用。

STRUCTURE AND SPECIES COMPOSITION OF GROUND BRYOPHYTE COMMUNITY OF HIGH-ALTITUDE YOUNG SILVICULTURAL CUTOVERS IN RANGTANG COUNTY, CHINA: EVALUATION ON EFFECTS OF CLEAR-CUTTING AND SILVICULTURAL MANAGEMENT

Aims Traditional forestry management influences biodiversity. Revealing effects of clear-cutting and silvicultural history on ground bryophyte communities is important for evaluating impacts of forest management on biodiversity. Methods We selected four sites with similar physical conditions but different development phases in Rangtang County. We investigated bryophyte and vascular plant vegetation, including species composition and structural characteristics, in 30 plots in each site. ANOVA analysis was used to detect differences among bryophyte communities, and the relationship between vascular plant and bryophyte communities was examined by partial correlations. Important findings Bryophyte composition changed significantly during developmental processes of young forests. Photophilic or pleurocarpous mosses were dominant species, while some hygrophilous mosses expanded their populations and become dominant species locally and drought-tolerant species occurred because of disturbance. Richness index (22–37) and diversity index (0.37–1.08) increased during the process of development, and the four young forestlands had differences in structural characteristics. There was a positive relationship between cover of tree and shrub layers and development of bryophytes. Shrub layer significantly promoted bryophyte richness, while pioneer grass with strong development and litter restrained bryophyte development. Characteristics of development in tree, shrub, litter layer and their interaction changed dynamically during the developmental process. Promoting development of tree and shrub layers has an important role on enhancing bryophytes.