Three-dimensional Canopy Structure in The Timberline Ecotone Dominated by Abies faxoniana
岷江冷杉林线交错带的植冠三维结构

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.