The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to unde...The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle in order to develop an effective monitoring and management strategy. In this study, the effects of hillside exposure （south- and north-facing）, host-tree locations according to relief （valley, mid-slope, and ridge-top） and tree diameters on RTB colonization were investigated in one valley （3 sites）. The results showed that （i） RTB clearly preferred colonizing pines growing on south-facing hillsides, especially in the valley; （ii） RTB preferred to colonize the pines growing at the valley rather than pines growing at mid-slope or on ridge-top; （iii） RTB preferred to colonize trees with large diameter over small and medium-sized pines; （iv） the attack density of RTBs （measured by pitch tubes/pine） was obviously higher on larger trees standing in the valley than other trees standing at other places. We conclude from RTB colonization patterns, that RTB prefers to attack large trees in the valley, which may be useful in developing a pest-management strategy.展开更多
The use of probability distribution functions for describing tree diameter at breast height provides useful information for forest resource evaluation and quantification. A series of probability distribution functions...The use of probability distribution functions for describing tree diameter at breast height provides useful information for forest resource evaluation and quantification. A series of probability distribution functions have been widely developed and applied for managing forest trees in conventional forest reserves without much consideration for trees outside forest reserves. The aim of this study is to evaluate and propose a suitable probability distribution function for trees in Agricultural landscapes. The study examined 3-parameter lognormal, Lognormal, 3-parameter Gamma, Gamma, 3-parameter Weibull and Weibull distribution functions, using the Maximum Likelihood method for fitting tree diameter at breast height. Three hundred and thirty-two temporary farmlands were randomly selected from which stem diameter of all living trees, with diameter ≥ 10.0 cm, were measured. Results of the statistical analysis showed that the 3-parameter lognormal distribution gave a superior description of the stem diameter with the least values of Anderson Darling (1.627) and Akaike Information Criterion (5962.0) statistics. Hence, the 3-parameter lognormal distribution function was found suitable for the stem diameter of trees in Agricultural landscapes in the study area.展开更多
基金This study was funded by the National Natural Science Foundation of China （Project 30525009 and 30621003） and Beijing Science and Technology Commission （D0705002040391）. Workers at Chakou Forest Farm, Gujiao, Shanxi Province, provided technical assistance in the field. We thank Emily Wheeler for editorial assistance.
文摘The alien red turpentine beetle （RTB）, Dendroctonus valens LeConte, is one of the most economically destructive forest pests in China, having killed more than 6 million pines in recent years. There is a need to understand the basic biology and ecology of the beetle in order to develop an effective monitoring and management strategy. In this study, the effects of hillside exposure （south- and north-facing）, host-tree locations according to relief （valley, mid-slope, and ridge-top） and tree diameters on RTB colonization were investigated in one valley （3 sites）. The results showed that （i） RTB clearly preferred colonizing pines growing on south-facing hillsides, especially in the valley; （ii） RTB preferred to colonize the pines growing at the valley rather than pines growing at mid-slope or on ridge-top; （iii） RTB preferred to colonize trees with large diameter over small and medium-sized pines; （iv） the attack density of RTBs （measured by pitch tubes/pine） was obviously higher on larger trees standing in the valley than other trees standing at other places. We conclude from RTB colonization patterns, that RTB prefers to attack large trees in the valley, which may be useful in developing a pest-management strategy.
文摘The use of probability distribution functions for describing tree diameter at breast height provides useful information for forest resource evaluation and quantification. A series of probability distribution functions have been widely developed and applied for managing forest trees in conventional forest reserves without much consideration for trees outside forest reserves. The aim of this study is to evaluate and propose a suitable probability distribution function for trees in Agricultural landscapes. The study examined 3-parameter lognormal, Lognormal, 3-parameter Gamma, Gamma, 3-parameter Weibull and Weibull distribution functions, using the Maximum Likelihood method for fitting tree diameter at breast height. Three hundred and thirty-two temporary farmlands were randomly selected from which stem diameter of all living trees, with diameter ≥ 10.0 cm, were measured. Results of the statistical analysis showed that the 3-parameter lognormal distribution gave a superior description of the stem diameter with the least values of Anderson Darling (1.627) and Akaike Information Criterion (5962.0) statistics. Hence, the 3-parameter lognormal distribution function was found suitable for the stem diameter of trees in Agricultural landscapes in the study area.
