Effects Of Vegetation Configuration On Soil Moisture In Wind-water Erosion Crisscross Region Of The Loess Plateau

The Loess Plateau is the region with the most serious soil erosion in China.The implementation of the project of returning farmland to forest and grassland has effectively improved this phenomenon,and also had a strong impact on the local ecological environment.Soil moisture is an important factor limiting vegetation growth in this area.The study on the variation law of soil moisture in different allocation plots in the water and wind erosion ecotone of the Loess Plateau has a certain reference basis for the rational arrangement of the allocation mode of vegetation restoration and the effective utilization of soil moisture.Taking Liudaogou small watershed in Shenmu city in Northern Shaanxi as the experimental area,this paper explores the impact of different allocation modes on soil moisture,monitors the vertical spatial difference of soil moisture in the plot under different alfalfa proportion for a long time,analyzes the change of soil moisture before and after the rainy season,and explores the temporal and spatial distribution of soil moisture in each shrub grass allocation plot according to the change of soil moisture in shrub grass allocation plot in different precipitation years,And analyze the change law of soil temperature and soil moisture under different land use types combined with meteorological data.The specific conclusions are as follows:(1)With the increase of alfalfa planting proportion,the average soil water content in the plot decreases.On the vertical section of 0-300 cm soil layer,the soil moisture in a single abandoned grassland is higher than that in the alfalfa configuration plot.In the equal proportion configuration plot,the soil moisture is affected by the slope position of Alfalfa land,and the soil moisture in the configuration plot is the lowest when alfalfa land is located on the slope.Supplemented by rainfall in rainy season,the water storage in 0-100 cm soil layer increases significantly,and the water storage in 100-300 cm soil layer changes slightly.When alfalfa is planted under the slope of the community,the soil water content of the adjacent parts of the two vegetation and the soil water content of the whole community are higher than that of Alfalfa on the slope of the community.Slope vegetation allocation should reduce the proportion of vegetation allocation with high water consumption.(2)The soil water content of shrub grass plot increases with the increase of soil depth,and finally tends to be stable.Under the influence of vegetation type,the soil water content of shrub grass plot is lower than that of single grassland.Among different allocation modes,Caragana land abandoned land alfalfa land allocation plot has the lowest water content.The change trend of soil water content in different allocation plots in dry years and normal years is consistent with that of rainfall,but lags behind rainfall in time.The change trend of different precipitation years with time is different.In 2019,the soil water content first increased and then decreased,and then increased.In 2020,the soil water content showed an upward trend.In 2021,the soil water content showed a change trend of first decreased and then increased.(3)Affected by soil texture and surface plants,the water content of soil profile at 10m depth first increases,then decreases and then increases.The water content of bare land varies seasonally in 0-200 cm soil layer,and there is no significant difference in 200-1000 cm soil layer.The consumption depth of soil water in bare land is 100 cm,the recharge depth is 200cm,and the soil water storage at the end of the season increases by 17.4 mm.There are differences in soil moisture in different seasons in 0-300 cm soil layer of alfalfa land.The soil moisture below 300 cm soil layer does not change in different seasons.The soil water consumption depth of alfalfa land is 300 cm,the recharge depth is 70 cm,and the water storage at the end of the season is reduced by 93.4 mm.The diurnal and seasonal changes of soil temperature in alfalfa land and bare land are similar to sinusoidal distribution.On the soil profile,with the increase of soil depth,the soil temperature decreases first and then increases in spring,and increases first and then decreases in autumn.The soil temperature decreases gradually in summer and increases gradually in winter.The annual range of soil temperature is 28.3 ~oC in 10 cm soil layer and 0.7 ~oC in 1000 cm soil layer,almost reaching constant temperature.