马尾松毛虫害林分失叶量估测研究

Estimation for Stand Defoliation Caused by Dendrolimus punctatus Damage

马尾松毛虫是马尾松的主要害虫,发生频繁、危害严重。林分失叶量可直接反映马尾松毛虫危害等级,但实测困难、费力。虫情级数具有预测林分失叶量的能力,据此提出一种间接估测马尾松毛虫害林分失叶量的方法。依据马尾松毛虫害林分失叶量与虫情级数的相关关系,以虫情级数作为林分失叶量估测的替代因子,提取5类光谱植被指数(差值植被指数、比值植被指数、归一化差值植被指数、土壤调整植被指数及转换型土壤调整植被指数)和3类地形因子(高程、坡度、坡向),同时运用数量化理论Ⅰ和多元统计回归分析方法对虫情级数进行模拟,确定最优估测方法与影响林分失叶量的主导因子,从而实现马尾松毛虫害林分失叶量与虫害等级的估测。以沙县为实验区,结果表明:(1)数量化理论Ⅰ、多元统计回归分析方法对虫情指数的总体估测精度分别为73.68%、70.10%;(2)影响虫情级数或林分失叶量的主导因子为DVI、坡度、坡向、高程,其中DVI的作用最大;(3)通过替代法,反映了沙县马尾松毛虫害林分失叶量的大致情况,危害程度以轻、中为主,只有极少部分区域灾害较为严重。所提出的间接估测马尾松毛虫害林分失叶量的方法具有可行性。

Dendrolimus punctatus is the main insect pest of Pinus massoniana,and it occurs frequently and harms seriously.Stand defoliation can directly reflect the damage grades by Dendrolimus punctatus,but it is difficult to measure actually.Damage degree is able to predict the stand defoliation,thus the paper put forward an indirect method to estimate stand defoliation caused by Dendrolimus punctatus damage.On the basis of the correlation between stand defoliation and damage degree by Dendrolimus punctatus damage,this method takes damage degree as the substitution of stand defoliation and extracted five spectral vegetation indices（DVI、RVI、NDVI、SAVI and TVI） and three terrain factors（elevation,slope,aspect）.After that,it makes use of both the quantitative theory Ⅰ and multivariate statistical regression analysis to simulate the damage degree in order to determine the optimal estimation method and the dominant factors influencing the stand defoliation and realize the stand defoliation and damage grades caused by Dendrolimus punctatus.Taking Shaxian as the experimental area,the results showed that：（1） the estimation accuracies of Quantitative Ⅰ and Multivariate Statistical Regression Analysis were 73.68% and 70.10% respectively;（2） the dominant factors influencing the damage degree of stand defoliation were DVI,slope,aspect and elevation,out of which DVI role is the greatest;（3） through substitution,it reflected the stand defoliation by Dendrolimus punctatus of Shaxian roughly,whose main conditions were light and medium and with very few serious regions.Above all,this indirect method put forward to estimate the stand defoliation caused by Dendrolimus punctatus has certain feasibility.