Effects Of Artificial Vegetation Types On Soil Aggregate Stability And Organic Carbon Fraction On The Loess Plateau In Western Shanxi Province

The loess area in western Shanxi is located in arid and water-deficient areas,with fragile ecological environment and serious soil erosion.Artificial vegetation restoration is one of the important measures to improve soil function.In this study,different types of artificial vegetation(Robinia pseudoacacia,Platycladus orientalis,Platycladus orientalis,Medicago sativa,and cropland land as control)in the loess area of western Shanxi were selected as the research object.Analysis of soil aggregates by dry sieve method and wet sieve method to determine soil organic carbon and its composition and soil glomalin-related protein,studied the changes of soil organic carbon pool,soil structure and soil glomalin-related protein in artificial vegetation and the relationship between the three,and explored the soil on this basis.The main conclusions of the carbon fixing mechanism are:(1)Artificial vegetation restoration is conducive to the improvement of soil aggregate stabilityThe percentage of dry sieve vegetation aggregates is mainly concentrated in> 2 mm large agglomerates and 0.25 ~ 0.053 mm microaggregates.The dry sieve aggregate content showed an irregular “ W ” type distribution,and the distribution of soil water stable aggregate content showed an uneven “ V ” type distribution.The percentage of water-stable aggregates is mainly concentrated in the< 0.053 mm fraction.The MWD(Mean Weight Diameter,MWD)values of mechanical stability and water stability are as follows: Platycladus orientalis >Robinia pseudoacacia > Platycladus orientalis> Medicago sativa > cropland.The percentage of aggregate destruction(PAD)of Robinia pseudoacacia,Medicago sativa and Platycladus orientalis decreased with the deepening of soil,and the percentage of aggregate destruction(PAD)of cropland and Platycladus orientalis increased with the deepening of soil.The >0.25 mm agglomerates of dry and wet sieves showed the largest amount of Platycladus orientalis.Artificial vegetation restoration is conducive to the improvement of soil aggregate stability.(2)Vegetation restoration is beneficial to soil active organic carbonThe distribution characteristics of soils organic carbon(SOC)in all soils and aggregates of different types of artificial vegetation decreased with the increase of soil layer.And there is a significant difference in the 0-30 cm soil layer.The order of total organic carbon content in the whole soil was: Juglans regia > cropland > Robinia pseudoacacia > Platycladus orientalis > Medicago sativa.The organic carbon content of the agglomerates is mainly concentrated in the> 2 mm fraction,and the soil organic carbon fixation is more dependent on the large agglomerates.The distribution characteristics of active organic carbon in all soils and aggregates of different types of artificial vegetation decreased with the increase of soil layer.The content of easily oxidized organic carbon(EOC)in aggregates was mainly< 0.053 mm,and the content of particulate organic carbon(POC)in aggregates was mainly 0.25 ~0.053 mm,the content of dissolved organic carbon(DOC)in the agglomerates is mainly 0.25~ 0.5 mm.Platycladus orientalis and latycladus orientalis help to aggregate accumulate active organic carbon.(3)Artificial vegetation significantly affects the GRSP components of whole soil and aggregateThe distribution characteristics of GRSP profiles and aggregates of different types of artificial vegetation gradually decreased with the deepening of soil layers.The content of the whole soil EE-GRSP is: Medicago sativa > Platycladus orientalis > cropland > Robinia pseudoacacia > Platycladus orientalis.The content of the whole soil T-GRSP is: Medicago sativa > Robinia pseudoacacia > cropland > Platycladus orientalis > Platycladus orientalis.The agglomerate GRSP components are mainly concentrated in the range of 2 ~0.053 mm,and the GRSP components in the 0-100 cm soil layer have significant differences.The profile of the EE-GRSP/SOC,T-GRSP/SOC ratio and the distribution characteristics of the aggregates increase with the increase of the soil layer.The contributionrate of GRSP whole soil and agglomerates increased with the increase of soil layer.the contribution rate of GRSP is mainly concentrated between 1 ~ 0.25 mm,Platycladus orientalis,and the contribution rate of GRSP is higher.(4)Artificial vegetation aggregate stability and correlation between organic carbon and glomalin.T-GRSP and SOC content were significantly positively correlated with MWD(p < 0.05),and there was a significant negative correlation between MWD and EE-GRSP/SOC ratio(p <0.05).The easily oxidized organic carbon(EOC)in the whole soil was significantly positively correlated with GRSP(p < 0.05).The particulate organic carbon(POC)of whole soil was significantly positively correlated with EE-GRSP and T-GRSP(p < 0.01).The dissolved organic carbon(DOC)was significantly positively correlated with T-GRSP(p < 0.01).There was a significant positive correlation between the 2 ~ 1 mm fractional MWD values and POC and EOC(p < 0.05).Both EE-GRSP and T-GRSP were significantly correlated with SOC and POC(p < 0.05).The 2 ~ 0.5 mm fractional MWD values were significantly correlated with EOC(p < 0.01).> 0.053 mm grade EE-GRSP had a significant positive correlation with SOC and POC(p < 0.01).