基于密度效应的杉木闽楠复层林邻株根系养分与AMF多样性的关系分析

The transformation of multi-layer forest can adjust the stand structure and improve the site quality,which plays an important role in maintaining the sustainable management of forest.However,the density effect of tree species in multi-layer forest is still the main limiting factor of stand productivity.In order to study the effect of tree species density on root growth and symbiotic AMF community composition in multi-layer forest,this paper selected the different-age multi-layer forest of Phoebe bournei formed by intercropping Phoebe bournei under Chinese fir(19a)forest as the research object,and set four different retention densities of Phoebe bournei(300 trees·hm-2,600 trees·hm-2,900 trees·hm-2,1200 trees·hm-2).Based on the nutrient characteristics of roots of Chinese fir and Phoebe bournei,combined with the variation characteristics of AMF diversity and community composition in root tissues,the internal relationship between root nutrient content and AMF community composition and its response to changes in competition intensity were analyzed.Research shows that:the contents of total nitrogen,total phosphorus and total potassium in roots increased significantly with the increase of competition intensity(p＜0.05).For Chinese fir,the root nutrient content was not significantly affected by competition intensity(p＞0.05).In different competition intensity treatments,the contents of total nitrogen,total carbon,total phosphorus and total potassium in roots of Phoebe bournei were higher than those of Chinese fir.The AMF isolated from the roots of Chinese fir were 4 orders,4 families,7 genera and 48 species,and the AMF isolated from the roots of Phoebe bournei were 3 orders,4 families,8 genera and 52 species.The number of AMF species detected in the roots of Phoebe bournei was greater than that of Chinese fir.The species of AMF at the Top5 level were basically classified into Glomus,and Glomus was the main dominant genus.Trees may help themselves to obtain nutrients and regulate interspecific relationships by promoting AMF diversity in roots to cope with competitive stress.