白龙江上游地区森林植物群落物种多样性的研究

CHARACRISTICS OF SPECIES DIVERSITY OF PLANT COMMUNITIES IN THE UPPER REACHES OF BAILONG RIVER

白龙江上游地区属长江防护林工程重点地区之一。根据 36个样地的调查资料 ,分析了该地区森林植物群落物种多样性的特征 :群落内各层物种丰富度指数的大小顺序为“灌木层 >草本层 >乔木层” ;均匀度指数变化比较复杂 ,在杜鹃巴山冷杉 (Rhododendronfastigiatum_Abiesfargesii)林中为“草本层 >灌木层 >乔木层” ,在苔藓巴山冷杉林中为“乔木层 >灌木层 >草本层” ,其余群落中为“灌木层 >草本层 >乔木层” ;多样性指数的大小顺序为“乔木层 <灌木层和草本层” ,而灌木层与草本层的多样性指数随林分郁闭度变化而变化 ,在郁闭度 30 %的杜鹃巴山冷杉林中 ,草本层大于灌木层 ,在郁闭度 47%的箭竹巴山冷杉林中 ,草本层和灌木层相当 ,在郁闭度 55 %以上的各个群落内 ,灌木层大于草本层。同一海拔不同坡向群落的物种多样性表现为分布于阳坡的油松 (Pinustabulaeformis)林大于分布于阴坡的草类云杉 (Piceaasperata)林。物种多样性沿海拔梯度的变化表现为随海拔升高先降低后增加 ,从海拔 2 4 0 0m的栎类阔叶林 ,2 60 0m的草类云杉林 ,2 80 0m的箭竹 (Sinarundinarianitida)巴山冷杉林 ,到 3 0 0 0m的苔藓巴山冷杉林和 3 2 0 0m的杜鹃巴山冷杉林 ,物种多样性依次下降 ,到海拔 3 40 0m的高山杜鹃

The upper reaches of Bailong River, a significant branch of the Yangtze River, is one of the important regions in the Yangtze River Natural Forest Protection Project. Based on the survey and the data from 36 plots, characteristics of species diversity of plant communities in the upper reaches of Bailong River were discussed in this paper. The study showed that richness index varied as follows: tree layer<herb layer<shrub layer. The evenness indices varied between communities as follows: a) Rhododendron fastigiatum _ Abies fargesii community: herb layer>shrub layer>tree layer; b) moss_ A. fargesii community: tree layer > shrub layer> herb layer; and c) other communities: shrub layer > herb layer> tree layer. Diversity indices in tree layer were lower than that in herb layer and in shrub layer. While the diversity indices between herb layer and shrub layer varied with shade density, i.e. greater the shade density, lower the diversity indices in herb layer. When shade density of stand was about 45%, diversity index in herb layer were almost equal to that in shrub layer; when shade density of stand was about 30%, diversity index in shrub layer were lower than that in herb layer; when shade density of stand was above 55%, diversity indices in shrub layer were higher than that in herb layer. General richness index, evenness indices and species diversity of Pinus tabulaeformis community distributed on the sunny slope were higher than that of the grass_ Picea asperata community growing on the shady slope along the same elevation zone (2 500_2 700 m). The study detected that general species diversity and general evenness indices of different plant communities decreased gradually from broadleaf mixed community dominated by Quercus liaotungensis at 2 400 m elevation, to grasses_ Picea asperata community at 2 600 m elevation, to bamboo ( Sinarundinaria nitida )_ A. fargesii community at 2 800 m elevation, to moss_ A. fargesii community at 3 000 m elevation, to R. fastigiatum _ A. fargesii community at 3 200 m elevation zone, and then progressively increased in R. fastigiatum shrubs from 3 400 m, with altitudinal increase. The study also indicated that species diversity and evenness index gradually increased from shrubs stage dominated by Spiraea alpina and Sibiraea angustata to broadleaf mixed forest stage dominated by Betula albo_sinensis , to broadleaf and needleleaf mixed forest stage dominated by B. albo_sinensis and Picea purpurea, and then decreased at the needleleaf community stage dominated by P. purpurea in the natural succession series of P. purpurea community after artificial logging.