青海大通河流域青杄林空间结构特征OA北大核心CSTPCD

As one of the major tree species occurring in Qinghai,Picea wilsonii plays important roles for soil and water conservation,climate regulation and biodiversity maintenance.In order to provide theoretical basis for the optimization of the structure and scientific management of local natural secondary forests,the P.wilsonii forests in Qinghai Daitong River basin were used as the research objects,and the sample plots were set up in the less disturbed areas to analyze the spatial structural characteristics.Twelve survey plots with an area of 20 m×20 m each were established in Beishan Forest Farm in Huzhu Tujia Autonomous County,Qinghai Province to conduct tally investigation.Each wood was checked and surveyed to calculate the angular scale,size ratio and mixing degree of individual trees and analyze their monodistribution and bi-nary distribution characteristics.The distribution of large and medium warp trees in the forest was mainly in random distribution,and small diameter trees showed a slightly clumped distribution;as the diameter level increased,the competitiveness of the forest increased;the mixed degree of each diameter level was ver-y low.The spatial distribution pattern of green dock forests was mainly random,with a slightly clumped distribution in the gently sloping areas;the overall size differentiation of the trees on different slopes was close to moderate,and the size differentiation of trees was small;the mixed degree of green dock forests was extremely low,mainly zero degree mixed.At different angular scales or mixing levels,the differences in stand size ratios between slopes were not significant and there was no obvious pattern.The natural sec-ondary forest communities in the study area are all in the middle and late stages of natural evolution.It is suggested that in the forest management process,its natural secondary state should be maintained,and there are no needs to adjust its mixed degree,the absolutely inferior forest individuals could be selectively cut down to improve the forest environment,increase lighting conditions,and promote renewal and sustain-able forest development.