The Effect Mechanism Of Fire On Forestry Pest

The forest fire occurs very frequently in our country. Fire acts on and effects forest ecosystem directly as a ecology element. Fire can affect the host and life condition of forest pests directly. The burned forests tend to be attacked by the forest pests and suffer a serious lost. The study designed many sample plots in some representational burned sites in Da xing an ling,Heihe,Yi chun , Mu Dan jiang and so on, in 2004, we made a in-depth research on the plots during the period when the forest insects break out, with the methods of both quantitative analysis and qualitative analysis, revealed the effect mechanism of fire to forest pests deeply, and put forward the integrity prevent measure. The results of the research are mainly as follow:1. After the research on the plot we found that, in the forests of Larix gmelinii Rupr.and Pinits sylvestris var.mongolica Litv.that was burned, there are many kinds of wood borers, with the Ips subelongatus Motsch, Monochamus sutor (Linnaeus) and M.urussovi (Fischer) as the pioneers and predominance genus ,with great quantity, which is more than 95% of the wood borers and others are genus of company. In the forests without fire we have not discovered the harm of the wood borers. Other forestry pests only did a little harm. There are few kinds of wood borers in the broadleaf forest of both burned and unburned, but the burned forests are more seriously harmed comparing with the unburned; the varieties and quantity of the pests are affected by the intensity of fire, by the research on the pests of different forest that are of different time period after fire show that: the trend of the variety of wood borer, the rate of trees that infected by pests, and the population are similar in different years, the incurrence leaf eating pests of different life history are of some dissimilarities in different years after fire.2. Forest pests incurrence was analyzed by a multiple logistic regression included diameter at breast height, percent live crown, char height, and fire age , and the result show that char height has a significant affection on forest pest incurrence, except Mudanjiang region, Then we had a simple linear regression to analysis char height and incurrence quantity of forest pest.3. We do a prevention cure experiment to Dendrolimus superans (Butler) and Clostera anastomosis Linnaeus using low intensity prescribed fire on Populus davidiana Dode. The result showed that in certain period of time low intensity prescribed fire can control the quantities of these two pests efficiently.4.Combine this study result and some correlate reports, form many point of view, we did a profound analysis about influence mechanism between fire and forest pests .5. Aiming at the incurrence law and characteristic of pests in burned areas, we put forward synthesis prevent countermeasure from some aspects including silvicultural control, chemical control, bio-prepratation, exohormone induce, and natural enemy's protection and utilization.