FIFTEEN-YEAR CHANGES OF TREE POPULATIONS IN THE SECONDARY SUBTROPICAL EVERGREEN BROAD-LEAVED FORESTS IN SOUTHWESTERN CHINA
The present study was conducted in the secondary su btrop ical evergreen broad-leaved forests at altitude 1650～1670m in Mt.Wawusha n National Forest Park,southwestern China.In order to understand stand restoratio n dynamics,the stand structure in three permanent 0.04hm2 plots for 3～4t imes were recorded from 1982 to 1997 and expounded the changes in 15 years about tree composition,important value index,several diversity indices,structure and volume productivity of both communities and populations.The results were followe d：11 tree species disappeared and about another 10 species entered into tree lay er in the stand,keeping tree layer dynamic equilibrium and developing tree speci es diversity.The dominant species,Castanopsis platyacantha,assumed the super ior status,but its important value(Ⅳ)was decreased.The position of secondary do minant species,Schima sinense and Lithocarpus hancei, are gradually enha nced with gradually increased Ⅳ.The changes of densities,DBH and height dis tribution of tree populations displayed that the secondary evergreen forest was developed from past single or double dominant tree species to double or three do minant trees,from single tree layer to multiple levels in vertical structure.And the resulting community becomes more complicated and more stable.The growth rat es of average height and DBH of all main trees were 24～48cm.a-1 an d 0 .34～1.10cm.a-1,respectively.According to the differentiation of grow th,the main trees could be divided into three growth groups of species：fast-gro wing group including species of Schima sinense and Acanthopanax evodiaefoliu s var.gracills,slow-growing group of Machilus pingii and Lithocarpu s hancei, and the group in between of Castanopsis platyacantha and Cycl ob alanopsis myrsinaefolia. Volume productivity of the dominant population increa s ed firstly and then decreased,but the secondary tree population increased quickl y all the time.Volume productivity of all tree population in 1997 was up to betw een 218m3.hm-2 and 235m3.hm-2,and the change of dominant p opulation was a key for community productivity.The relations of DBH,height g rowt h and volume productivity in various density of the main tree populations indica ted that the densities was one of the most important factors influencing product ivity of tree populations under common environment with the interactions among t ree populations.It is suggested that there is no contradiction between tree spec ies diversity conservation and high volume productivity in forest restoration pr ocess.
国家科技期刊平台
NSTL
万方数据
维普
