Research On Ecological Restoration Technologies For Controlling Dendrolimus Punctatus Calamity

Dendrolimus punctatus Walker becomes the most serious " pest " of the South provinces' forests in our country, wide to distribute range, heavy to endanger area, large to annual generation, great to reproduce capacity, strong to move or fly, which are extremely serious to endanger. After studying decades of a lot of scholars, they have known the distribution, biological characteristic, population dynamics, prediction methods, and some control methods of it. However, so far, the calamity of Dendrolimus punctatus Walker has been failed to totally remove all the time. According to the annual pest situation report, though defend pests every year, manage pests every year, but there are calamity of Dendrolimus punctatus Walker every year, and the trend is increased in some places.In order to find a method that can solve the calamity of Dendrolimus punctatus Walker fundamentally, this thesis attempts to combine insect ecology principles, restoration ecology principles and landscape ecology principles, to control the calamity of Dendrolimus punctatus Walker through ecological restoration technologies and measures. This method hasn't been reported to control Dendrolimus punctatus Walker. According to the thought, this thesis has studied in 6 aspects.First part, the thesis has probed into the endangerment area, morphological character, ecological characteristics of Dendrolimus punctatus Walke, and commonly used control methods. This thesis has also studied the progress for the restoration ecology and commonsense methods.Second part, this thesis has introduced the current situation of the studying area, and chosen a appropriate technical route and research approaches.The third part, this thesis has studied the current situations and the degradation mechanism of the forest ecosystem of hilly county. First of all, this thesis has studied the current degradation situations of the forest ecosystem of hilly county by studying the degradation of the structure and function, and drawn the following result: (1)Pine forest is the largest in Chang Sha County, which accounts for 76.89% of the total.(2)The pine forest ecosystem makes up simply, and the species are poor . (3)Bio-diversity is low in the system. (4)Community structure is unstable. Community structure and food web structure are simplified. (5) The stability reduce. There are often calamities of Dendrolimus punctatus Walker. (6)Land capability declines seriously, the content of granule is lower , the soil bulk density is higher, the gross porosity and capillary porosity are large, the production forces level is low than which of evergreen broadleaved forest. (7)The stress resistance is weak. (8)The effect of adjusting microclimate is low. (9)Soil and water conservation benefit is weak, and soil and water losses is serious. (10)Material cycle and energy flow have taken place the bad change. The second, the thesis has used multi-approach comprehensive diagnostic methods and disturbance degree methods todiagnose the degradation degree of the pine forest ecosystem in hilly county. The disturbance degree of Changsha County is 3.47. The degradation degree of the pine forest ecosystem is moderate. Otherwise, There are more serious calamity of Dendrolimus punctatus Walker in the area where is degradating serious. At last, the thesis has studied the mechanism of degradation of the pine forest ecosystem in hilly county. It is caused by internal cause and external cause.The fourth part, this thesis has studied the ecology mechanism of the happen of the calamity. Firstly, this study has studied the relations of the calamity of Dendrolimus punctatus Walker and the forest landscape structure. The patch number, the average area of the patches, the proportions of area and the maximum patch index are the largest where often are calamity. The pest calamity is not serious where the landscape diversity index and landscape proportionnable are large. Secondly, the thesis has analysed the relations of the calamity of Dendrolimus punctatus Walker and regional landscape structure. The types of regional langdscape, the landscape Shannon index, the landcape Simpson index and the landscape diversity index are the smallest, and the landscape proportionnable is the largest where often are calamity of Dendrolimus punctatus Walker. At the last, this thesis has studied the ecology mechanism of the happen of calamity of Dendrolimus punctatus Walker with the principal component analysis method. From the results we know that the most close relation influence factor is the stand factor, the second influence factor is the growth and development of trees, the last is the site factor.The fifth part, this thesis has studied the feasibility of restoring the hilly county to control the calamity through studying the ecology condition, social culture economic condition and technology. The result shown that it is feasible.The sixth part, this thesis has studied the ecological restoration technology. For controlling the calamity of Dendrolimus punctatus Walker by using the ecological restoration technology, the first is to divide the types of Dendrolimus punctatus Walker calamity taking place in Chang Sha County. The second is to take different methods to restore according to different conditions. The methods include setting up ecological isolation strips, remaking the corridors that the Dendrolimus punctatus Walker disseminate through them, finding the landscape control point to restore, closing the land for reforestation in some serious calamity area, remarking stand structure, and going on the village land use planning, etc.At last, this thesis has studied the desired benefit. It is expected that the total benefit can be up to 13 203 million yuan, among them the ecological environment benefit is the largest, accounts for 98. 90% of the total benefit. The project can produce heavy direct economic benefits too. There is 144.67 million yuan in all.