Spatial Patterns Of Soil Carbon And Their Control In The Steppe Of Northern Mongolian Plateau

Soil carbon storage is the largest terrestrialcarbon pools.Climatic,edaphic and biotic conditions are generally regarded as the primary controls over soilorganic carbon.Importantly,the interrelation of soil organic carbon and thesedrivers and their potential connection networks are rarely assessed quantitatively.Using observations of soil organic carbon content(SOC)and density(SOCD)and soil inorganic carbon content(SIC)and density(SICD)dynamics with detailed soil properties at 46 sites under different grassland ecosystem across the northern Mongolian plateau,we exploredthe spatial patterns of SOC,SIC,SOCD and SICD,and investigated the direct and indirect effects of climate,soil properties,and vegetation(a total of 22 variables)on SOC and SOCD.The mainresults are as follows.1.Random Forest showed that soil properties were good predictors for SOC and SOCD than climate and vegetation;While,soil texture and pH significantly affected SICand SICD.2.Path analysis identified anetwork of intercorrelations of climate,soil properties and vegetation indeterminingSOC and SOCD.The direct correlation of SOC and SOCD with climate was significantly weakenedif removing the effects of soil properties.Climate was only secondary predictors for SOC and SOCD,while soil properties were acrucial factor for predicting SOC stocks and dynamics at largerscales.3.The patterns of SIC and SICD was dependent on soil properties,especially soil texture andpH.4.There were changes in SIC and SICDdue to increased SOC and SOCD.The relationship between SIC and SOC,SICD and SOCD varied among vegetation types.Positive relationship was found in meadow steppe and desert steppe,however,both negative and positive relationshipwastestedin typical steppe.For the whole region,there was significant positive relationship between SIC and SOC,SICD and SOCD.