不同立地条件下昆虫群落对松毛虫密度影响的估计(英文)

天敌在松毛虫种群动态中起重要作用，但把天敌的作用加入系统管理模型中却很困难。本文试图用林分因子代替天敌的作用，因为林分条件可以方便地用于系统模型中。通过对浙江省衢县、常山县和龙游县不同立地条件的222块样地的调查数据的分析，从70多科的昆虫群落中选择了16个关键种（科），并对林分因子和各样地关键种的种数、个体数、多样性之间的关系进行了典型相关分析。结果表明郁闭度和植被条件（灌木层盖度、灌木层高度、草木层盖度、草木层高度、总盖度）是刻划昆虫群落功能的关键林分因子。根据郁闭度的变化和植被条件用系统聚类方法可以把林区分为四种类型，这四种类型林地的昆虫多样性指数、种数、个体数量和松毛虫的密度都存在明显差异；在每种林地都建立了松毛虫密度的变化率与关键林分因子间的回归模型，所有的回归的相关系数都相当高（0．924－0．964），因此可以认为对林地的分类是合理的，而且用林分因子评估天敌的影响在实践中是可行的。

EVALUATING THE IMPACT OF INSECT COMMUNITY ON PINE CATERPILLAR DENSITY IN DIFFERENT STAND CONDITIONS

Natural enemies play an important role in inhibiting population growth of pine caterpillar, but they are difficult to be used in systematic management. This paper attempts to usesome forest stand factors to substitute the effect of natural enemies, which could be used in management models. Through the studies from more than 200 stand plots with different stand conditions inQu County, Changshan County, and Longyou County of Zhejiang Province, 16 Predominant speciesgroups from insect community were selected, and the canonical comlation coefficient between the diversity index, species number, individual number of predominant species and the stand factors wasanalyzed. The results indicated that the canopy density and ground vegetation were tbe key stand factors for characterizing the function of insect community. The forest area was divided into four typesaccording to the variation of canopy and vegetation conditions by using cluster analysis. The regression models between the rate of variation of pine caterpillar density and the forest factors includingcanopy density and vegetation covers were developed in each type of forests. There were significantdifferences in diversity index, species number, individual number of insect community and populationdensity of pine caterpillar among four types of forests, and correlation coefficients of the four regression models were rather high (r= 0. 924-0. 964 ). This means that the classification of tbe foreststands is reasonable and the stand factors can characterize the effect of natural enemies in practice.