Interaction Between Different Sand Fixing Shrubs And Micro Topography Features On Soil Characteristics In The Aeolian Sandy Land Of Eastern Ningxia,China.

Straw checkerboard afforestation is a main measure of wind prevention and sand fixation,which plays an irreplaceable role in quick sand control and vegetation restoration.In arid and semi-arid desertification areas of Northwest China,planting sand fixing shrubs can not only prevent and fix sand,So as to achieve the effect of preventing wind and fixing sand and promoting vegetation restoration of desertification grassland.It has been widely used in many climate types of China.In this study,the sand dunes in the mixed sand fixation area of Caragana korshinskii and Corethrodendron scoparium and the mixed sand fixation area of Caragana korshinskii and Calligonum mongolicum were selected as the research objects.This paper analyzes the influence and interaction of two sand fixing shrub mixed forests on soil characteristics under different micro topography site conditions,and preliminarily reveals the influence of sand fixing shrub and different micro topography site conditions on the physical and chemical properties of sand dune soil.The main results are as follows:(1)The results show that the physical structure of the soil at the bottom of the dune is better than that at the top of the dune,at the bottom of the dune,at the middle of the windward slope and at the middle of the leeward slope.Compared with the mixed planting of different sand fixing shrubs,the mixed planting of Caragana korshinskii and Corethrodendron scoparium can improve the soil texture,and has a greater impact on soil nutrients and water.(2)In the mixed planting area of Caragana korshinskii and Corethrodendron scoparium,compared with other micro topography,the soil particles at the bottom of the sand dune are continuously refined,the silt particles are significantly increased,and the soil fractal dimension is high;The soil particle size on the top of the hill,the middle of the windward slope and the leeward slope is more than 100 μm is less.The soil nutrient accumulation in the bottom of the hill was higher than that in the other three micro topographies,followed by the middle of the leeward slope.Soil depth had a great influence on soil organic matter and total nitrogen in the mixed forest of Caragana korshinskii and Corethrodendron scoparium;It has little effect on total phosphorus and potassium.(3)In the mixed planting area of Caragana korshinskii and Calligonum mongolicum,compared with other micro topography,the very fine and medium sand particles in the bottom of the dune increased,and the fine sand particles in the top of the dune increased,with high fractal dimension,followed by the middle of the slope;It can effectively increase the content of nitrogen,phosphorus and organic matter in the surface soil of all terrain parts,and also has a positive effect on the soil water storage of 20-30 cm.The change of soil nitrogen,phosphorus and organic matter content in different micro topography is the middle of windward slope>the middle of leeward slope>the top of hill,while the change of soil potassium content and water content in different micro topography is the top of hill>the bottom of hill>the middle of windward slope>the middle of leeward slope.(4)Compared with mixed planting of Caragana korshinskii and Calligonum mongolicum and mixed planting of Caragana korshinskii and Corethrodendron scoparium,mixed planting of Caragana korshinskii and Corethrodendron scoparium had an increasing effect on the nutrient content of surface soil,and the total nitrogen content and organic matter content of 0-10 cm soil were significantly increased;It has a positive effect on 20-30 cm soil moisture storage.It is suggested that the afforestation density at the top of the slope and the middle of the leeward slope can be appropriately increased when the restoration measures of sand fixation shrub are carried out in the later stage,so as to better improve the soil nutrient level at the top of the slope and the middle of the leeward slope.Results showed that the differentiation of soil physical properties and nutrient characteristics on the dune slope was the result of the interaction of sand fixation shrub mixed forest type and micro topography.