秦岭中段松栎混交林群落数量分类与排序

依据陕西省境内秦岭山脉中段设置的34个样地调查资料,从植物物种组成、植物群落与地形因子之间的关系等对该区域松栎混交林群落进行TWINSPAN分类和DCCA排序。结果表明:(1)研究区34个样地共记录维管束植物297种,隶属于77科178属,其中被子植物72科,裸子植物2科,蕨类植物3科;分布较广的植物有:松科、壳斗科、蔷薇科、菊科、禾本科和百合科。(2)TWINSPAN聚类结果将样地群落划分为13个群丛,其中以油松+锐齿槲栎为建群种的群丛最多,占总群丛数量40%,是该区主要的松栎混交林群落类型。(3)样地的DCCA排序结果表明,第一轴明显地反映出群落分布沿海拔、坡位的变化,第二轴主要表现出群落分布沿坡向、坡度的变化趋势;其中海拔、坡度与DCCA一、二轴相关系数分别达到最大值(-0.946 2、-0.795 7),是对该群落分布起决定性作用的因子。(4)研究区主要优势物种的DCCA排序与样地的DCCA排序综合反映出该区松栎混交林群落分布的地形梯度。

Numerical Classification and Ordination of Pine and Oak Mixed Forest Communities in the Middle Part of Qinling Mountains

Based on data from 34 plots of the middle part of Qinling Mountains in Shaanxi Province,the ecological gradients of the plant communities were studied by the methods of TWINSPAN and DCCA,in terms of the interactions between plant species and communities and topographical factors.The results indicate that:(1)34 plots record 297 species vascular plants,belong to 77 families 178 genera.Among those,72 families Angiospermae plants,2 families Gymnospermae plants,and 3 families Pteridphyta plants.The wide distribution species include Pinaceae,Fagaceae,Rosaceae,Compositae,Gramineae,and Liliaceae.(2)Based on TWINSPAN,34 plots were classified into 13 associations,and the number of associations which dominant species are Pinus tabulaeformis+Quercus aliena var.accuteserrata,possessed about 40% of the total number,is the widely distributed mixed type of the study area.(3) The first of DCCA ordination axes indicates the altitude and slope position gradients,and the second of that indicates the aspect and slope gradients.The correlation coefficients of elevation,slope and DCCA one and two axis arrived the most values,respectively (-0.946 2,-0.795 7).The main factors restricting distribution of the communities are altitude and slope in this area.(4)The DCCA ordination of dominant species and samples simultaneously reflect the topography gradients of pine and oak mixed forest communities in this area.