青藏高原东北边缘云杉-冷杉林火烧迹地不同坡向植物群落结构与多样性研究

Vegetation community structure and diversity in a burned area of Picea asperata-Abies fabri forest on different aspects on the northeastern margin of the Qinghai-Tibetan Plateau

采用野外调查与植物群落相似性分析,研究了青藏高原东北边缘云杉-冷杉林火烧迹地不同坡向植物群落组成和物种多样性特点,结果表明:经过火后15年恢复,云杉-冷杉火烧迹地有草本植物22科40属46种,其中优势科有菊科,种类数最多(11种),其次为毛茛科6种,伞形科4种,蓼科3种,茜草科、龙胆科、蔷薇科和忍冬科各2种;在草地北坡、西北坡、东北坡和东坡分别分布着高山冷蕨+密生薹草+总状橐吾群落、密生薹草+高山冷蕨+野草莓群落、密生薹草+野草莓+箭竹群落和密生薹草+野草莓+总状橐吾群落;北坡的Margarlef丰富度指数和Shannon-Wiener多样性指数最高,东坡的Simpson优势度指数最高,而4个坡向草地的Pielou均匀度指数差异不显著;不同坡向植物群落存在一定的梯度格局,但是彼此分布之间存在一定的差异。通过研究分析可以得出:随着坡向由阴坡(北坡)到半阳坡(东坡)的变化,植被盖度逐渐减小;北坡的Margarlef丰富度指数和Shannon-Wiener多样性指数均最大,其次是西北坡和东北坡,而东坡的最小;不同坡向植被类型分异现象较弱,植物群落存在相似性。

In this study,we conducted field surveys to determine the composition and diversity of the plant community in a burned area of Picea asperata-Abies fabri forest on the northeastern margin of the Qinghai-Tibetan Plateau. Non-metric multidimensional scaling methods were used to analyze the data. Twenty-two families,40 genera,and 46 species were identified in the burned areas. The dominant families were Compositae(11),Ranunculaceae(6),Apiaceae(4),Polygonaceae(3),Rubiaceae(2),Gentianaceae(2),Rosaceae(2),and Caprifoliaceae(2). Different communities were distributed on slopes with different aspects:a Cystopteris montana+Carex crebra+Ligularia botryodes community on the north-facing(N) slope, a C. crebra+C. montana+Fragaria vesca community on the northwest-facing slope,a C. crebra+ F. vesca+Fargesia spathacea community on the northeast-facing slope,and a C. crebra+F. vesca+L. botryodes community on the east-facing(E)slope.The community on the N slope had the highest Margalef’s richness index and Shannon-Wiener diversity values,while the community on E slopes had the highest Simpson’s dominance index. There were no significant differences in Pielou’s evenness index of vegetation among the four different slopes. A gradient distribution pattern of vegetation existed on the different slopes,and there was some overlap among community distributions. The extent of vegetation cover decreased from the cloudy slope(N)to the semi-sunny slope(E). The slopes were ranked,from highest values of Margalef’s richness index and Shannon-Wiener diversity index to lowest,as follows:N>NW>NE>E.