Abstract:

Objective: Accurately identifying the intensity difference, variation trend and inter-annual variation of forest pest disasters in different periods in China is the premise for formulating effective forest pest disaster response strategies and implementing differentiated fiscal subsidy policies. It is of great significance to prevent forestry disaster risk, improve the risk control level of forest resources and enhance the supply capacity of forestry carbon sink. Method: The numerical analysis method was used to analyze the general occurance of forest biohazards with the statistical data of forest biohazards from 1998 to 2018. According to the variation values of the incidence of forest diseases, insect pests and rodent disasters in China from 1998 to 2018, the interannual changes of the intensity of various disasters were analyzed. The grey correlation degree method was further used to determine the correlation degree of forest diseases, insect pests and rodents in forestry pest disasters and the weight of their impact on forest resources, and hence to determine the comprehensive index of forest pest disasters in China from 1998 to 2018. Finally, the comprehensive grade of forest pest disasters in China in the above period was divided. Result: 1) From 1998 to 2018, insect pests was the main forest pest disaster in China, followed by disease and rodent. However, the increase of the area of rodents infestation was larger than that of diseases and insect pests.Compared with 1998, the growth rate of the area affected by rodents, diseases and insect pests in 2018 increased by 156.36, 83.09 and 57.72 percentage points, respectively. 2) The intensity of all kinds of forest pest disasters was different in different years. In the study period, 2007 was the year with the highest occurrence intensity of forest pests and rodents, while 2018 was the year with the highest occurrence intensity of forest diseases. 3) According to the comprehensive disaster index of forest pests from 1998 to 2018, the forest pest disaster in China from 1998 to 2018 can be divided into three stages. The first stage was from 1998 to 2005, during which the comprehensive disaster level of forest pest was the lowest, and the harm of forest pest to forest resources was the least. The second stage was from 2006 to 2008, during which the forest pest caused the most serious damage to forest resources, and the comprehensive disaster grade was the highest, especially in 2007. The third stage was from 2009 to 2018. In this stage, the comprehensive level of disaster to some extent decreased, but the overall degree of disaster was still relatively serious. Conclusion: From 1998 to 2018, the total area of forestry pest disasters in China is on increase. Among them, the mild disasters account for the majority, but their area is increasing year by year, while the area and incidence of moderate and severe disasters fluctuate and decrease. The annual area of forest insect pests is relatively serious, and the area of rodent pests is increasing rapidly. At present, forest disasters have reached the highest disaster intensity in the research period. In addition, although the comprehensive level of forest pest disaster has declined, it is still at a relatively high level, and the area of pest disasters is increasing year by year, and the prevention and control situation is still serious. It may be effective to maintain the ecological security and promote the construction of ecological civilization in China by adopting differentiated forest disaster response measures, focusing on curbing the rapid growth trend of forest rodent pests, reducing the incidence of forest insect pests and strengthening the prevention and control of severe diseases.

Key words: forest pests disaster, disaster level, comprehensive evaluation, sequential variation