高寒区青海云杉人工林密度与林下植物多样性的关系

为了研究青海云杉人工林密度对林下植物多样性的影响及二者的关系,探明维持植物多样性、人工林生态系统稳定性及其健康状况的合理林分密度,以青海大通宝库林区6种不同密度（3 400株/hm²、2 900株/hm²、2 600株/hm²、2 300株/hm²、2 150株/hm²、1 750株/hm²）25年生青海云杉人工林林下植物的重要值、丰富度指数、多样性指数、均匀度指数为指标,对林下植被多样性随林分密度的变化规律进行分析。结果表明:(1) 青海云杉人工林下共有维管束植物60种,非维管束植物1种,隶属于29科45属。（2）灌木层植被优势种受密度影响较大,草本层植被优势种受密度影响较小。（3）青海云杉密度分别与灌木层和草本层的S指数、H′指数、Ea指数均呈显著相关关系,且相关系数分别为0.688、0.937、0.762和 0.679、0.870、0.505。（4）随着青海云杉密度的增加,林下植被多样性呈先减少后增大再减少的变化规律,且密度为2 600株/hm²时,林下植物多样性综合得分最高。研究认为,青海云杉林下植被多样性对其密度响应具有非同步性;密度为2 600株/hm²时比较适合林下植被生长,并保持林下植物多样性水平。

Relationship between Plantation Density and the Plants Diversity under Forest of Picea crassifolia in Alpine Region

Six types of 25 years stand density(3 400 plants/hm²,2 900 plants/hm²,2 600 plants/hm²,2 300 plants/hm²,2 150 plants/hm² and 1 750 plants/hm²) were selected,and the law of importance values,species richness,species diversity index,evenness index with stand density were analyzed to study the relationship between stand density and plant diversity of under growth of Picea crassifolia plantation in Baoku Forest farm at Datong County of Qinghai Province.The aim of this paper was to verify an appropriate stand density that could improve plants diversity and maintain the stability of plantation ecosystem.The result showed that:(1)There were 60 vascular plants and one nonvascular plant in 45 families and 29 genera of under growth in P.crassifolia in the study area.(2)Stand density had a significant influence on dominant plants in shrub layer,but the influence was not obvious in herb layer;(3)There was a positive correlation between stand diversity and species richness index,Shannon-Wiener index and Alatalo index in shrub layer,and the correlation coefficients were 0.688,0.937,0.762,respectively.With respect to herb layer,the correlation between them was also obvious,and the correlation coefficients were 0.679,0.870,0.505,respectively.(4)As stand density increased,plants diversity decreased firstly,then increased and finally decreased.The research suggested that the response of plant diversity of understory vegetation to stand density was non-synchronous.When density arrived at 2 600 hm²,the understory plant diversity reached the maximum,which indicated that the density was more appropriate for growth and development of understory vegetation,and can contribute to an increase in forest diversity.