Optimization of stumping method based on wind control benefit for Salix psammophila shrub in Mu Us sandy land

In order to solve the problem of shrub decline in Mu Us sandy land, ecological flat stumping method was designed to make the shrub stay the characteristic of plexus structure sustainably. The wind field structure and wind control benefit of Salix psammophila in different stump method were studied. Then the theoretical guidance can be provided to Mu Us sandy land in the future. Up to date, few studies are conducted to investigate the wind field structure and wind control benefit of shrub in Mu Us sandy land. The test set includes 6 kinds of flat stump intensity (0, 0.2Ф, 0.4Ф, 0.6Ф, 0.8Ф, 1.0Ф, where Ф is Fluffy diameter of shrub), 3 kinds of flat stump model (model A: stump from the shrub windward face to leeward according to the flat stump intensity along the direction, model B: stump on both sides of the shrub at the same time according to the flat stump intensity along the direction, model C: stump on both sides of the shrub at the same time from the shrub's middle 1/2 faults according to the flat stump intensity along the direction the same below) to stay the exist of the characteristics of the shrub structure sustainably. The morphological parameters of dune were measured, and the redundant natural vegetation will influence the test. The other indexes of the shrub and the wind's indexes which were also measured relatively. Relationship between morphological parameters and wind control benefit of the shrub after stumping was analyzed, then the best method of stump can be elected according to the result. The test result showed: there were no significant changes for shrub's morphological parameters and the wind control benefits of both mode A and mode B within the range of 0-0.4Ф of the stumping intensity. However, according to the wind control benefits, mode B is better than mode A when the stumping intensity is 0-0.4Ф. When the stumping intensity was 0.6Ф and above of which, the speed of wind decreased significantly on the leeward side, and the wind control's distance shortened gradually in all 3 modes. The stumping intensity of 0.4Ф was a critical point of the mutation. According to this research and comparison with the other studies, there were unity between the morphological parameters and wind control benefit of the shrub, and the change of morphological parameters decided the wind control benefit immediately. Flow structure will change obviously when the stumping more than 0.4Ф. In addition, in spring, when the branches and leaves of Salix psammophila were not yet unfolded, there also was a significant correlation between the wind control benefits and each morphological parameters and the porosity of shrub, but the correlation within the wind control benefits and porosity of shrub was the biggest, which indicated that the morphological parameter that performed the greatest impact on wind control benefits was porosity of shrub. It was also found that a reasonable stumping method was following: Salix psammophila shrubs on fixed dunes should be stumped with mode B, and the stumping intensity was recommended to be 0.4Ф.