Hetrogeneity Of Soil Moisture,Carbon And Glomalin-related Soil Protein On Caragana Korshinskii Plantations On Sloping Land In Loess Hilly Region

The ecological environment in the loess hilly region is fragile and soil and water loss is serious.Artificial vegetation restoration is one of the important measures to control soil and water loss and improve soil function in the region.This study choose the Ningxia autonomous region natural guyuan city ecological experimental station huang has a slope belt bringing the Caragana korshinskii Kom.of compound ecosystem 15,25 and 35 years,and of weeds to grow as the research object,based on field investigation,sampling,indoor measurement and statistics,the research of soil moisture content(SMC),organic carbon(SOC)and glomalin-related soil protein(GRSP)soil spatial distribution and its variation characteristics,and find out the three main influencing factors,so as to provide certain scientific basis for regional ecological assessment and management.The main conclusions are as follows:(1)The increase of plantation years of C.korshinskii significantly reduced soil moisture storage(SMCS)and its heterogeneity.The SMC content in different soil layers was higher in the shallow layer(0-40 cm)than that in the grassy land at different slope positions.With the deepening of soil layer,the SMC content decreased gradually.The increasing plantation years of C.korshinskii decreased the SMCS in the soil layer of 0-100 cm,and there was a significant water deficit in various fields.But there was no significant difference in SMCS between shrub and grass.Gauss and spherical models were the main geostatistical models for spatial variation of slope SMCS,and the C.korshinskii plot fitting was the best in 35 years.SMCS at different soil depths showed weak spatial autocorrelation,and SOC may be the influencing factor of soil moisture.(2)C.korshinskii cultivation improved soil organic carbon storage(SOCS)and carbon sequestration capacity.C.korshinskii plantation significantly increased SOC content and reserves in the 0-100 cm soil layer,and the cumulative increase effect was obvious in the deep layer(40-100 cm).The SOC of different slope positions showed that the SOC of each sample plot 15-30 m away from the top of the slope and the SOC of the lowest position away from the top of the slope was higher than that of other slopes in different soil layers away from the top of the slope.The SOC content in different soil layers was higher at 0-40 cm,and gradually decreased with the deepening of soil layers.The differences of SOCS bands in shrub and grass belts are different due to the difference of soil layer.Compared with the wasteland,the carbon sequestration of C.korshinskii after 15 and 35 years of plantation had a positive accumulation effect,while the carbon sequestration of C.korshinskii after 25 years had a lower negative deficit effect.The geostatistics of SOCS spatial variation on slope surface is mainly based on Gaussian model.The 60-100 cm of CK sample site shows strong spatial autocorrelation,while other SOCS with different depths show weak spatial autocorrelation.The band may be the influencing factor of SOC distribution.(3)The content of GRSP in soil increased first and then decreased with the increase of the age of C.korshinskii,and decreased with the increase of soil depth.The contents of total extracted GRSP(T-GRSP)and easily extracted GRSP(EE-GRSP)components were significantly different in the 0-40 cm soil layer,with the variation ranges of 1.90-2.55 and 0.58-0.89 mg/g,respectively.In different soil layers,the content decreased with the depth deepening.The content of GRSP component in C.korshinskii zone was higher than that in grass zone.The ratios of T-GREP /SOC and EE-GREP /SOC increased with soil depth.Soil GRSP of different years and depths showed weak spatial autocorrelation.(4)The SMC,SOC and GRSP were significantly correlated in the shrub-grass ecosystem.Long-term slope shrub-grass complex ecosystem reduces grassland biomass and increases shrub volume.SMC,SOC and GRSP were positively correlated with grass biomass and negatively correlated with shrub volume.SMC and SOC were positively correlated with GRSP.Segment analysis(VPA)showed that the planting years,elevation and slope position were the main factors affecting SMC and SOC,while the years,slope position and strip were the main factors affecting GRSP.In general,long-term planting of C.korshinskii on sloping land in the loess hilly region increased surface SOC and GRSP contents,but also significantly caused SMC deficiency and reduced spatial heterogeneity of each index.The comprehensive effect of plantation years and slope position of C.korshinskii on sloping land should be fully considered when evaluating regional soil moisture and carbon.