| Soil moisture is the core of sandy land system in semi-arid region,and its spatio-temporal changes directly affect the uptake of water and nutrients by vegetation roots,which largely determines the restoration of sandy land vegetation and the improvement of ecological environment.Evapotranspiration reflects the migration process of soil moisture in SPAC system.In the process of plantation construction,water consumption characteristics of vegetation and its adaptability to semi-arid environment should be considered.Therefore,it is of great practical significance to strengthen the study on spatial and temporal variation of soil moisture and evapotranspiration characteristics of shrub in semi-arid area for optimal allocation of vegetation and effective utilization of water resources.This study typical artificial thickets Wu Us sandy land as the research object,from March 2018 to October 2019 CNC503DR neutron instrument has been applied to the determination of 0?300 cm soil moisture content,analysis of leeward slope under the condition of different vegetation types(natural grassland,Amygdalus pedunculata,Pall Salix psammophila,Amorpha fruticosa Linn),different site conditions(windward slope,top,leeward slope),different Amygdalus pedunculata planting density(0.22plants/m~2,0.27 plants/m~2,0.33 plants/m~2)of soil moisture variation of temporal and spatial.Based on the principle of water balance,the characteristics of evapotranspiration water consumption in the shrub plots of Amygdalus pedunculata under different sites and planting densities were studied,and the factors affecting the evapotranspiration water consumption in the shrub plots were analyzed,and the main conclusions are as follows:(1)During the monitoring period,the average soil moisture content of different vegetation types in 0?300 cm soil layer was natural grassland>Amorpha fruticosa Linn>Amygdalus pedunculata>Pall Salix psammophila;In terms of seasonal changes,2018showed as autumn>summer>spring,spring>summer>autumn(2019).The variation coefficient of soil moisture time(season)of each vegetation type was decreased with the in increase of soil depth.The vertical variation coefficient was larger in summer and autumn.The time stability analysis showed that the soil moisture content in the soil layers of100?120 cm,120?140 cm,100?120 cm and 50?60 cm could be used to estimate the averages soil moisture in the 0?300 cm profiles of nature grassland,Amygdalus pedunculata,Pall Salix psammophila and Amorpha fruticosa Linn.(2)The average soil moisture content of the shrub with planting density of 0.33plants/m~2was higher,following 0.22 plants/m~2and 0.27 plants/m~2.Affected by precipitation at the end of 2018,the soil moisture content in spring was higher under the three densities in the following year.The vertical distribution of soil moisture content in0?300 cm profile under the three density conditions was significantly different in summer,followed by autumn and spring.The temporal variation coefficient of soil moisture under three densities in the higher in the shallow layer and lower in the deep layer.The time stability analysis showed that the soil layers of 160?180 cm,100?120 cm and 140?160 cm cloud better estimate the planting density of 0.22 plants/m~2,0.27 plants/m~2and0.33plants/m~2in the profiles of 0?300 cm,respectively.(3)The average soil moisture content of the under different site conditions in 0?300cm soil layers was windward slope>dune top>leeward slope,and the differences among the three are significant,all of them are medium variation.In terms of seasonal changes,the overall performance of 2018 was autumn>summer>spring and spring>summer>autumn.The soil moisture content in 0?300 cm soil layer had great difference under the three site conditions,and the rapid increase of soil moisture content in 160?300 cm windward slope.The soil water content in the 0-50 cm soil layer fluctuated greatly in time,while the deep soil water content fluctuated stably in time.The vertical variation coefficient was summer>autumn>spring.Time stability analysis showed that the soil layers of 70?80,40?50 and 140?160 cm could estimate the average soil moisture content of 0?300 cm profiles in leeward slope,dune top and windward slope,respectively.(4)The evapotranspiration water consumption of shrub plots showed that the evapotranspiration water consumption of shrub plots under different site conditions was windward slope>leeward slope>dune top;The density of Amygdalus pedunculata was0.33 plants/m~2>0.27 plants/m~2>0.22 plants/m~2,the evapotranspiration from early July to mid-August was the largest,and the shrub area had more soil water savings during the monitoring period of 2018,which could meet the normal growth of Amygdalus pedunculata.In 2018,evapotranspiration water consumption of shrub plots under different site conditions was significantly positively correlated with precipitation(p<0.01),and not significantly in 2019.Under the condition of the slope of the plot and the vegetation factors above the ground,the content of soil organic matter can be increased,which had an obvious promoting effect on the evapotranspiration water consumption of the shrub plot addition,the larger soil sand and gravel content in the profile can form a thicker sand layer,which significantly inhibits the evapotranspiration water consumption in shrub communities. |
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