Effect Of Extreme Climate On The Occurrence Tendency Of Three Forest Pests

Forest diseases and pests seriously restrict the development of forestry in our country.Climate change is one of the key factors that cause forest pests and diseases common occurrence and cause serious damage.Under the background of global climate change,the frequent occurrence of extreme climate events has a significant effect on forest pests and diseases,so it is necessary to carry out the research on the effects of extreme climate changes on forest diseases and pests.In this paper,the data of annual incidence rate of Tomicus yunnanensis?Parocneria orienta and Monochamus alternatus Hope from 2002 to 2012 in Southwest region was used as the research object.According to the meteorological data of the study area,two important indexes were calculated and analyzed the influence on the occurrence of forest diseases and pests.One is Standardized Precipitation Evapotranspiration Index,short for SPEI which characterized the drought degree and the low temperature and the other one is sleeting frost index,short for K.This research provides a new approach to predict and forecast forest pests,what's more,the results have guiding significance for forest pests prevention and control when the extreme climate events occurs.The results showed that:(1)The SPEI index wich based on the difference between precipitation and potential evaporation can play very good response to the interannual variation of wet and dry in each city.So it is a very good index used to study the drought and its impact.The low temperature and sleeting frost index K which was calculated by 5 basic meteorological factors such as mean temperature?mean minimum temperature?the?0? duration?precipitation and rainy days in process can respond well to the extent of the disaster in different areas.(2)The incidence rate of Tomicus yunnanensis is significantly positive correlation with SPEI,i.e.drought has an inhibition to the occurrence of Tomicus yunnanensis.In addition,the SPEI is significantly negative correlation with the the incidence rate of Parocneria orienta,i.e.drought can promote the occurrence of Parocneria orienta.But there is no significant correlation between SPEI and the incidence rate of Monochamus alternatus Hope.(3)There is a positive correlation between the K and the incidence rate of Parocneria orienta,i.e.frost disaster has an obvious inhibitory effect on the occurrence of Parocneria orienta.Variance analysis showed that there was significant difference between the rate of different grades of low temperature and sleeting frost disaster.There is a negative correlation between K and incidence rate of Monochamus alternatus Hope,i.e.low temperature and sleeting frost disaster promotes the occurance of Monochamus alternatus Hope.The method of polynomial regression was used for regression modeling to the incidence rate of Monochamus alternatus Hope in Guizhou province.This model has better precision and practical values,so the K can be used as a predictive index.