岷江冷杉林线交错带的植冠三维结构

Three-dimensional Canopy Structure in The Timberline Ecotone Dominated by Abies faxoniana

卧龙自然保护区巴郎山岷江冷杉林线交错带植冠三维结构定量分析表明 :植冠明显地分化成两个叶层 ,两叶层间有 1 .4m的无叶植冠区。以岷江冷杉、大叶金顶杜鹃和红毛花楸为优势 ,构成了林线植冠的主要成分。植冠深度较小的为低矮灌木种类 ,深度最大的是乔木层树种。林线植冠的物种组成较丰富 ,每个垂直取样冠层平均有 2个以上物种。林线的植冠空间占有率最高的是高大的星毛杜鹃 ,其次是岷江冷杉 ,但植冠高度以岷江冷杉最高 ,故林线交错带林相以岷江冷杉为优势。物种的盖度与单位面积的植冠体积间有较好的线性关系 ,物种的植冠体积大致可用其盖度值乘以系数 1 .2 1来计算。

An investigation was made in the timberline ecotone of Abies faxoniana to determine the quantitative characteristics of three\|dimensional canopy structure The vertical foliages of the community were composed of two layers of leaves and there was 1 4 m distance between them, where hardly observed any leaf. The leaf layers in the canopy were dominated by species such as A. faxoniana, Rhododendron faberi subsp. prattii and Sorbus rufopilosa . The canopy of the shrub species was shallower than that of the tree species. On the average, about 2.5 species occurred in the canopy. R. faberi subsp. prattii and A. faxoniana occupied the hargest and second largest space in the canopy, respectively. However, the A. faxoniana had tallest in the canopy. Therefore, the timberline ecotone was morphologically dominated by A. faxoniana. The canopy volume of a species was positively correlative with its cover and can be calculated as the product of the coverage and the coefficient of 1 21.