Soil Organic Carbon Stability And Its Correlation With Soil Properties In Different Vegetation Zones Of Vegetation Restoration On The Loess Plateau

The content and stability of soil organic carbon have a crucial impact on the decomposition and storage of soil carbon,which is significant for the prediction of climate change and the sustainable development of ecosystem.In this study,the physical components,chemical properties,biological properties and soil easily oxidized carbon components of gradient soils in different latitudes of the Loess Plateau were studied.We aimed to provide scientific bases for ecological restoration evaluation,soil carbon pool management and sustainable development in the Loess Plateau.The main results are as follows:(1)Vegetation zones have an impact on soil physical component,chemical property,biological properties and soil organic stability.The soil organic stability was higher in the steppe zone,overall.The soil organic carbon stability index(SI)grassland zone was 15.88% and 84.28% higher than that of forest zone,respectively.The soil organic carbon stability index of grassland in 1-10 a and >20a increased by 15.88% and 84.28% compared with the forest zone,respectively.The soil organic carbon stability index(SI)of arbors in three age stages in grassland zone increased by 37.92%,59.27% and 118.89%,respectively,compared with the forest zone.However,the contents of soil clay and soil silt,macroaggregate stability of arbors,soil nutrient contents,soil basic respiration,induced respiration,soil catalase activity,Phosphatase activity,urease activity,soil organic carbon contents and the contents of active organic carbon components(very liable oxidizable carbon components C1,liable oxidizable carbon components C2 and less liable oxidizable carbon components C3)were relatively higher in forest zone.The contents of soil sand,microaggregate stability,soil pH,soil polyphenol oxidase activity and soil organic carbon stability were relatively higher in the steppe zone.(2)Vegetation types had an impact on chemical property,biological properties and soil organic carbon stability.Soil organic carbon stability was higher in shrubs,overall.Soil organic carbon stability index(SI)in 0-10 a and >20a of shurbs in the steppe zone was 1.53 and 1.57 times respectively higher than that in grasslands.The soil organic carbon stability index(SI)of the shrubs in the forest of 0-10 a was 2.45 and 1.41 times that of arbors in grasslands,respectively.Trees in the forest zone had relatively higher soil nutrient contents,soil basic respiration,induced respiration,soil phosphatase activity,urease activity,sucrase activity,soil organic carbon contents and C1 contents.However,shrubs had relatively higher soil polyphenol oxidase activity and soil organic carbon stability.(3)Recovery years decreased the soil organic carbon stability,overall.The soil organic carbon stability index(SI)of arbors and grasslands in the steppe zone decreased by 0.03 and 0.09,respectively.The soil organic carbon stability index(SI)of grasslands,shrubs and arbors in the forest-steppe zone decreased by 0.53,0.78 and 0.55,respectively.The changes of soil organic carbon stability index(SI)in the forest zone exhibited was poor.Recovery years increased soil macroaggregate stability,soil nutrient contents,soil basic respiration,induced respiration,soil sucrase activity,catalase activity,phosphatase activity,polyphenol oxidase activity,urease activity,soil organic carbon contents,the contents of active organic carbon component(C1,C2 and C3)in the forest-steppe zone and the forest zone.(4)Soil organic carbon stability had a relatively and strongly positive correlation with the content of soil clay and soil silt and pH.However,it had a relatively and strongly positive correlation to the content of sand components,microaggregate stability,soil organic matters,soil total nitrogen,soil alkali-hydrolyzable nitrogen,soil sucrase activity,soil phosphatase activity and carbon pool quality.Our study found that the stability of soil organic carbon in steppe zone was higher than that in forest-steppe zone and forest zone,but decreased gradually with the recovery years.The changes of organic carbon stability were mainly related to the contents of soil sand and soil nutrients,soil respiration and the increase of soil enzyme activity.The results provided scientific bases for ecological restoration evaluation and soil carbon pool management in the Loess Plateau.