缙云山森林土壤速效N的分布规律

The distribution regularity of forest soil available nitrogen on Jinyun Mt.

研究了缙云山森林生态系统4个演替阶段的土壤速效N分布变化规律．结果表明，①土壤速效N在不同群落中均具有明显的层次性，即A（腐殖质层）＞B（沉积层）＞C（母质层）相关分析结果表明，土壤速效N含量与土壤厚度呈极显著负相关（P＜0．01）．②A，B层土壤速效N含量随演替的方向逐渐增加，即灌草丛＜马尾松纯林＜马尾松－川灰木混交林＜常绿阔叶林．这是因为土壤速效N含量与土壤含水量、有机质含量、枯枝落叶厚度呈正相关．③物种多样性指数随演替方向逐渐升高，但在灌木层、草本层略有波动相关分析结果表明，其与A，B两层土壤速效N含量存在不同程度的相关关系．

The distribution characteristics of soil avalilable nitrogen and changing regularity of species diversity of forest ecosystem of Mt. Jinyun are studied. The results are as follows: ①Soil available nitrogen of dtheren conununities shows an evident gradient, i. e., A horizon(humus layer) > B horizon(deposit layer)> C horizon(parent material layer). There is very significantly and negatively correlations between soil available nitrogen and soil depth. ②Soil available nitrogen of A and B horizons increases along successional directions, i. e., shrub-grassland < Pinus massonia pure forest < P. massonta-Symplocos sethvenensis mixed forest < evergreen broadleaved forest. There is positively correlations between soil available nitrogen and the content of water, organic matter and litters thickness. ③Species diversity indice orderly inereases with seral directions, but its fluctuations exist in shrub layer and grass layer. It shows different degree's correlations between the content of available nitrogen of A, B horizons and species diversity indice.