Characteristics of Soil Organic Carbon Density in Two Stands of Xinjiashan in Qinling Mountains Based on a New Method of Deducting Root Volume

【Objective】 Through the comparison among the estimated result of the soil organic carbon density in the spruce（Picea asperata） and red birch（Betula albosinensis） natural forests in the Xinjiashan Forest Farm in Qinling Mountains with different estimation method, we tested the improvement of the new method on estimation accuracy by subtracting the root volume.【Method】 The organic carbon densities of the mineral soil layers（top soil layer, core soil layer and subsoil layer） and organic soil layers（non/semi-decomposed layer namely L + F and fully decomposed layer of litter namely H） were estimated separately. For the estimation of the organic carbon density in the mineral soil layer, the estimation accuracy is improved by deducting the root volume of trees based on the existing method. The method for estimating the volume content of roots in each layer contains 4 steps as follow. Firstly, the root biomass of a single tree was estimated with the regression equations proposed by the previous study, which is multip