科尔沁沙地典型乔灌植被的深层渗漏与土壤水分补给特征OA

[Objective]This study aims to investigate the impacts of typical sand-fixing vegetation(Caragana microphylla shrubs and Populus alba var.pyramidalis trees)on deep percolation and soil moisture in different hydro-meteorological years in Horqin Sandy Land,so as to provide a scientific basis for water management in forest and grassland ecosystems to support the"Three-North"Shelter Forest Program and the ecological restoration efforts in Horqin and Hunsanzhake sandy regions.[Methods]During growing seasons(April to October)of 2022(wet year)and 2023(dry year),the real-time quantitative monitoring of deep percolation across typical shrub and tree vegetation covers and mobile sandy areas in Horqin Sandy Land was conducted by using a self-developed deep percolation recorder(YWB-01).The differences in deep percolation were compared between different sand fixing vegetation types in two different hydro-meteorological years on a daily and monthly scale.Soil moisture at 0–200 cm depths was monitored to elucidate variations in the relative extractable water in the shallow(0–40 cm),middle(40–120 cm),and deep(120–200 cm)soil layers between the wet and drought years.Finally,based on water balance analysis,the water replenishment capacity of different vegetation types was assessed.[Result]1)In each hydro-meteorological year,the relative extractable water in all soil layers was significantly higher in mobile sandy areas than in vegetated sites(P<0.05).There was no significant difference in the relative extractable water in shallow layer(0–40 cm)between shrub and tree sites,while the middle and deep layers(40–120 cm and 120–200 cm)had significantly higher relative extractable water in shrub sites compared to tree sites(P<0.05).2)The variation characteristics of deep percolation across different hydro-meteorological years exhibited similar patterns in different vegetation types,with the highest percolation flux in mobile sand dunes,followed by shrublands,and lowest in forested areas.The magnitude of deep percolation was greater in the wet year than that in drought year.On daily scales,deep percolation in mobile sand dunes in different hydro-meteorological years exceeded that in shrublands at least approximately 73.86％of days,with an even higher proportion on a monthly basis.Throughout the study period,deep percolation was consistently higher in mobile sand dunes and shrublands than that in forested sites.3)The evapotranspiration in shrub and tree vegetation was significantly higher in the wet year compared to the drought year.Shrublands contributed to soil water recharge,whereas forests led to soil moisture deficits.[Conclusion]In different hydro-meteorological years,vegetation-covered sites exhibit significantly reduced deep percolation relative to mobile sand dunes at both daily and monthly scales,with a more pronounced reduction observed in forested sands.The relative extractable water within the soil profile beneath vegetation is markedly lower than in mobile sand dunes;forested sites consume more mid-and deep-layer soil water,resulting in notable soil moisture deficits.