Study On The Control Of Main Harmful Rodents At The Planted Forest Ecosystem In Yan'an

Returned arable land for plantation and grow grass, and restoration and rebuilt vegetation of tree and grass is a very important measurement for water and soil conservation, desertification control and eco-environmental improve in west part of China. However, the young tree and grass was serious harmed by the rodents, such as zokor, rabbit and pika, and which had affected the vegetation rebuilt and restoration, especially for the progress of returned arable land for plantation and grow grass. The thesis discussed the habit of living, activity and damage of 4 kind of rodents, Guansu zokor (Myospalax cansus), Chinese zokor {Myospalax fontanierii), daurian pika {Ochotona daurica) and cape hare (Lepus capensis), to planted forest ecosystem and its control by measurements of ecological, no-pollution chemical, physical obstructing and chemical or biochemical repelling effect by means of investigation, field test and cage rearing experimentation in Yan'an plantation area, Shaanxi Province. The results were showed are as follows:1. The amount of grass that Myospalax cansus feeding is a limiting factor to the number of zokor. The higher canopy density of plantation, the less forest grassland or underground, then the less the number of Myospalax cansus. The best way for control Myospalax cansus is to decrease the food source, especially grass with tap root, by bionomic control measurements such as loosening the topsoil to distract the hole system, implanting of Periua frutescensl which hold a function of zokor repelling, control of grass in the plantation site by manual or herbicide, and popularization of agri-forestry.2. The KRS shows a good palatability for Myospalax fontanierii. The intake coefficient of Myospalax fontanierii to KRS is 0.88-1.03. The controlling effects of KRS for Myospalax fontanierii are 100.0% at indoors and 83.7%-92.3% at planted forest site. Of which the controlling effects are better in spring and autumn than in summer season. Three baiting methods, putting the bait into a hole bored on the top of zokor's nets, putting the bait into a hole of zokor's nets by transverse cutting the hole, and putting the bait into a effective hole by the hole cutting and blockage method, were also tested. The results indicated that the method of the hole cutting and blockage is the best in three, for it saves the bait, cost lowest and increase the validity of baiting to 70.0%-92.0%. It is 22% more effective if baiting in spring than in summer.3. The experiments for Ochotona daurica control were done on the effects of four types of rodenticides including phosacetim, bromodiolone, zinphos and KRS. The results showed that the effects of KRS was the best, up to 87.39%, bromodiolone with wheat 77.32%, phosacetim with wheat 70.41%, and zinphos with potato 65.99%. The optimal baiting dose was 5 grams. There were no significant difference among the bait of fresh bean, potato and wheat when the control effects were tested. And the effects were not related to the date of baiting.4. The damage of Lepus capensis to the young tree at the unclosed plantation site was quite serious. Among the 26 tree species, there are 7 tree species such as Hippophae rhamnoides, Amygdalus sibirca, Malus pumila, Pinus tabulaeformis et al with the highest damage degree by Lepus capensis, 9 tree species such as Amorpha fruticosa, Populus simonii, Ulmus pumila, Ailanthus altissima, Sophora daridii et al with the slight damage degree by Lepus capensis. Compare with control, they are effective measurements for Lepus capensiscontrol by coating stem with beef tallow, used of diesel oil, dipping roots in muddy water with RPA solution of 150 times, Spraying leaves of seedling with RPA solution of 400-450 times can alleviate damage of Lepus capensis, obstructing with twig fence, and combining obstructing with twig fence with dipping roots or with spraying leaves, respectively. Of which the best way for controlling Lepus capensis is combining obstructing with twig fence with dipping roots, which can reduce the damage 80.2 %.5. Using the technique of the stress resistance bag and deep-hole-planting had a good effect of drought resistance and rodent repelling in the arid rolling and gully loess region, which improved the survival rate of afforestation 38.9%-40.7%, decreased the rodent damage index 0.23-0.33, compared with the control.