【摘要】 通过草本植物群落的分类和排序 ,结合对乔木和灌木分布的分析 ,确定了五台山高山林线的几条植被界线以及五台山森林上限附近植被的性质。结果表明 :1 )阳坡林线的海拔范围为 2 60 5～ 2 790m ,阴坡林线的海拔范围为 2 81 0～ 3 0 1 5m ;2 )草本植物群落随海拔高度的变化比较明显 ,阴坡和阳坡从郁闭林到山顶均依次分布林下草本层、林缘草甸、亚高山灌丛草甸、高山草甸 ,草本植物的分布很好地体现了林线内部景观的差异性 ;3)海拔高度是高山林线附近草本植物群落空间分异的决定性因素更多还原

【Abstract】 As a transitional zone from closed forest to alpine vegetation, timber line is sensitive to climatic change in two aspects, fluctuation of its boundari es and changes to its structure. Therefore, the demarcation of vegetation limits and clarification of vegetation patterns of alpine timberline is critical to st udies on the response of alpine timberline to climatic change. Mt. Wutai, with a summit of 3 058 m a.s.l., is the highest mountain in North Chi n a. It is also one of several mountains which reach the climatically controlled a lpine timberline in the temperate broadleaved forest zone in China. Former studi es were focused on the vegetation classification of meadows, vertical changes of plant species diversity and micro to meso_scale patterns of the meadow near the summit. Vegetation analysis on a large scale is still essential to understand t he characteristics of vegetation near the timberline. Vegetation investigation was made at 10 m elevation intervals on the shady slope and 20₂5 m on the sunny slope from the upper forest limit to the mountain summ it. A total of 280 relevès on the shady slope and 75 on the sunny slope were ma de. TWINSPAN was used to do vegetation classification of herbaceous communities, and to show the relationship between distribution of plant communities and envi ronmental conditions was shown using DCA. After classification and ordination of herbaceous communities and analyses of distribution of trees and shrubs, vegeta tion boundaries of alpine timberline were delimited and vegetation characteristi cs of the upper forest boundary were clarified in this paper. On the shady slope, alpine timberline ranges from 2 810 m to 3 015 m a.s.l. T he timberline is dominated by Larix principis_rupprechtii with Picea meyer i and Betula albo_sinensis. The quantity of cones demonstrates that the re generation ability of Larix principis_rupprechtii is much better than that o f Picea meyeri. On the sunny slope, alpine timberline ranges from 2 605 m to 2 790 m a.s.l.. It is dominated by Picea meyeri with some Larix principis _rupprechtii. 4 herbaceous communities, understory herbaceous layer, meadow at forest edge , subalpine scrubby meadow and alpine meadow, were distinguished by TWINSPAN on both slopes. The herbaceous communities change markedly with altitude. Understor y herbaceous layer, meadow at forest edge, subalpine scrubby meadow and alpine m eadow occur in sequence from upper closed forest to mountain summit on both shad y and sunny slopes. DCA results showed that elevation is closely related to the changes of herba ceous communities, implying a key role of climate conditions in the spatial diff erentiation of herbaceous communities.更多还原