Spatial Variation Of Soil Vegetation In Tengger Desert Grassus Region

Taking mechanical sand barrier as a guide,and then biological sand fixation has always been the accepted engineering sand governance model.In recent years,the traditional material sand barrier grid has attracted much attention for its remarkable sand-fixing effect.However,there is a lack of continuous observations of changes in plant and soil properties after the establishment of the wheat straw grid in the early studies,so that data on plant settlement processes and soil property changes in the wheat straw grid are not available.This study uses the method of space instead of time to explore the effect of grass squares on the spatial distribution of plant communities and soil characteristics from the existence to the absence.The research time is based on the validity period of the grass square,and the space is based on the actual size of the grass square.The grass grid will not be patched during the research process,and the selection relationship between the grass grid and the plant in the natural state is maximized.The results of the study will further explain the effect of grass squares on vegetation establishment and provide new reference for the development of new materials for sand fixation in the future.(1)The community diversity during the grass checkered sand fixation increased,but the species richness did not increase linearly with the increase of recovery time,and the species of herbaceous plants changed significantly.The grass square has a great effect on the soil moisture content of the 0-30cm soil layer during the effective sand fixation period,and the downward migration speed of the dry sand layer as a whole is reduced,and the range of the dry sand layer is reduced.Especially in the second year of sand fixation,the soil water storage capacity reached the maximum,and natural plants such as Chenopodium spp.And insects entered.(2)Three types of population distribution were involved in the study.The annual herb mainly shows two types of uniform distribution and aggregate distribution,but most of them are mainly aggregate distribution.The flower sticks and Artemisia annua were mainly distributed randomly and aggregated.The distribution types in different recovery years changed with the change of spatial scale.In 1-2a plots,the distribution is mainly random,and at 3a,it turns into an aggregated distribution,and the degree of aggregation increases with increasing spatial scale.By analyzing the frequency of plants,that is,the location of the number distribution,herbaceous plants have a high probability of appearing hot spots in the presence of grass squares(ie,1-3a plots),which are consistent with the areas where the numbers are concentrated.Sticks grow mostly in the middle area of the grass grid.When the grass grid does not exist,herbaceous plants mostly gather in the center area of the original grass grid.(3)The soil particles in the study plots are mainly distributed in the range of 50-100 and 100-250?m,which are very fine sand and fine sand.The proportion of particles<2?m and>500?m is very small,and 0%in 2a and 5a.The grain content in-5cm and 10-20cm soil layers increased rapidly.With the extension of the grass grid,the soil nutrient content increased significantly,especially in the 0-5cm soil layer,and the soil nutrient content in the 0-5cm soil layer in the 2a plot was higher than that in the 3a plot,mainly because of the Root function of annual plants.The soil nutrient content in the 5-10cm and 10-20cm soil layers of the 5a plot was related to the root effect of shrub plants in the plot.The relatively high soil nutrient content in the grass grid mostly appeared in the grass grid side and the four corner areas,and rarely occurred in the middle and central areas,which coincided with the distribution of high-frequency areas of plant growth in the grass grid.(4)The soil characteristics that affect the distribution of plant numbers within the grass grid under the restoration years are different,which are mainly related to the plant species and reproduction methods in the community.The dominant species in the community are annual herbaceous plants.The soil characteristics that affect their quantity distribution are the fractal dimension of the soil particles and the soil water content in the 0-5 cm soil layer.The dominant species in the community are shrubs and Artemisia annua,and the soil characteristics that affect their quantity distribution are 5-10cm and 10-20cm soil moisture content.