| 1. | Based on the principle of significant effect of soil fertility factors on forest growth , soil physical factors ( natural water content , bulk density , total porosity , capillary porosity , aggregate degree , coarse silt and physical clay ) , chemical factors ( om . total n , alkali - hytrolyzable n , total p , humus and ha / fa ) and biological factors ( urease , acidphosphotase , invertase and microbes ) were selected as evaluation index system of soil fertility . applying principal component analysis , soil ifi of subalpine coniferous forest was calculated
从土壤物理、化学、生物学三方面出发，建立了川西亚高山针叶林不同演替阶段土壤肥力评价指标体系，应用主成分分析，计算出不同演替阶段土壤肥力综合指标值( ifi ) ，各演替阶段大小顺序为： 10年生云杉林地迹地原始林地次生桦木林地30年生云杉林地20年生云杉林地50年生云杉林地60年生云杉林地40年生云杉林地。 |
