华北土石山区天然次生林枯立木数量特征与分布格局

枯立木广泛存在于森林生态系统中,对森林的发展与演替有着十分重要的影响。以河北省木兰围场国有林场北沟林场天然次生林(面积为4hm2)植被群落调查为基础,分析研究了华北土石山区天然次生林枯立木树种组成、径级结构、生物量和分布格局。研究结果显示,研究区天然次生林枯立木分属8个乔木种群,密度为79.25株/hm2,占全部乔木的10.13%;枯立木生物量为18.46t/hm2,占全部乔木生物量的6.88%;山杨枯立木数量和生物量分别占全部枯立木的83.60%和90.58%,是样地中枯立木数量和生物量最大的树种;枯立木胸径(DBH)分配以DBH<22cm为主;林分内所有枯立木的平均角尺度值为0.543,呈随机分布。

Quantity Characteristics and Distribution Pattern of Standing Dead Trees in Natural Secondary Forests of Rocky Mountain Area in Northern China

Standing dead trees(SDT)are widespread in forest ecosystems and have a particular important influence on forest development and succession.Based on vegetation community survey in plots of 4hm2 in Mulan—Weichang forest farm of Hebei Province,this study analyzed the species,diameter structure,biomass and distribution pattern of SDT in the rocky mountain area of Northern China.The results indicate that the SDT involved eight species.The density of the SDT was 79.25stems/hm2,accounting for 10.13%of total tree numbers in the plots.The biomass of the SDT was 18.46t/hm2,accounting for 6.88%of the total biomass in the plots.Among them,both the number and the biomass of Populus were the greatest,accounting for 83.60%and 90.58%of all the SDT,respectively.The diameter at breast height(DBH)of the majority of the SDT was smaller than 22cm.The average uniform angle index of all the SDT of the forest is 0.543,indicating a random distribution pattern.