昆嵛山腮扁叶蜂虫基指数模型

Pest Based Index Model of Cephalcia kunyushanica in Kunyushan Mountains

[目的]为通过构建昆嵛山腮扁叶蜂虫基指数(Pest based index,PBI)评价体系,定量评价出与林分因子共同作用后,立地因子对赤松纯林中昆嵛山腮扁叶蜂发生程度的作用等级。[方法]本研究基于森林虫害发生的基本原理,将影响昆嵛山腮扁叶蜂的结果归因于林分因子和立地因子的综合作用。在相同龄阶的赤松纯林生态系统中设立临时样地,筛选影响昆嵛山腮扁叶蜂发生的关键林分因子,建立关键林分因子与昆嵛山腮扁叶蜂虫情指数的函数关系,选取最优模型作为主曲线;将主曲线等比值拉伸得昆嵛山腮扁叶蜂虫基指数曲线群,其自下而上依次表示不同的虫基指数,即立地对昆嵛山腮扁叶蜂发生程度的作用等级。[结果]1)基于森林虫害发生的基本原理,提出了虫基指数的概念。2)确定了昆嵛山腮扁叶蜂虫基指数的定量方法,它包含样地的设立、虫情指数的调查、林分因子和立地因子的调查、关键林分因子的筛选、基准点的确定、备选主曲线模型的建立、主曲线模型的确定和评价、主曲线的绘制及曲线群的建立共9个步骤。3)逐步回归和偏相关分析确定冠幅是影响昆嵛山腮扁叶蜂发生的关键林分因子,依据所提定量方法建立主曲线方程:Q=75.53/(1+e-0.84x+3.40),决定系数R2=0.5230,说明拟合方程较可靠,用该模型预估昆嵛山腮扁叶蜂的虫情指数时,平均预估精度是89.28%。4)将昆嵛山腮扁叶蜂虫基指数主曲线等比值拉伸得曲线群,即建立了定量评价体系。体系中的5条曲线自下而上分别表示腮扁叶蜂发生的不同程度。[结论]昆嵛山腮扁叶蜂虫基指数主曲线模型和曲线群图可以定量评价赤松林的立地因子对昆嵛山腮扁叶蜂的潜在发生程度的作用等级,为赤松纯林合理、有效的管理提供理论基础,它将成为森林有害生物生态控制方法的重要组成部分。

[Objective] To establish a pest based index(PBI) evaluation system of Kunyushan web-spinning sawfly(Cephalcia kunyushanica) and to quantitatively evaluate the effects of site factor on the occurrence degree of C. kunyushanica co-affected with other stand factors in pure forest. [Method] Based on the basic principles of forest pest occurrence, the results affecting the occurrence of C. kunyushanica were attributed to the comprehensive effect of stand factor and site factor. Temporary sample plots were set up in the pure forest ecosystem of Japanese red pine(Pinus densiflora) with the same age-gradation to choose the key stand factors affecting the occurrence of C. kunyushanica, the functional relationship between the key stand factors and the pest severity index of C. kunyushanica were establish, and the optimal model was select as the guide curve. The PBI curve group of C. kunyushanica was obtained by stretching the guide curve in an equal proportion, and the bottom up of the curve showed different PBIs, i.e.the effect level of site factors on the occurrence degree of C. kunyushanica. [Result](1) Based on the basic principle of forest pest occurrence, the concept PBI was proposed.(2) The PBI quantitative method of C. kunyushanica was determined, which contained 9 steps: setting sample, investigating the pest severity index of stands, investigating the site factor and stand factor, screening the key stand factor, determining the data of stand factor, establishing the alternative guide curve model, determining and evaluating guide curve model, drawing the guide curve, and establishing the curve groups.(3) Stepwise regression and partial correlation analysis showed that crown width was the key stand factor affecting the occurrence of C. kunyushanica. The guide curve equation was established according to the proposed quantitative method: Q=75.53/(1+e-0.84 x+3.40), and the determination coefficient was R2=0.523 0, indicating that the fitting equation was reliable. The average estimation accuracy of this model was 89.28% when using it to estimate the pest severity index.(4) A quantitative evaluation system was established by stretching the main curves of the PBI of red spot blight in equal proportions to form a curve group. The five curves in the system represented the different degrees of occurrence of C. kunyushanica respectively from bottom to top. [Conclusion] This study indicates that the guide curve model and curve group diagram of the PBI of C. kunyushanica can quantitatively evaluate the effect of site factors on the potential occurrence degree of C. kunyushanica, and can be used as an important tool in the ecological control of forest pests.