Sensitivity analysis of variables correlated to soil organic carbon in Chinese fir plantation under the Grain for Green Program

In order to reveal the change mechanism and main driving factors of the soil organic carbon in Chinese fir plantation under the Grain for Green Program，Sanjiangkou Town，Xingyi City in Guizhou Province was chosen as area for field investigation and soil sampling，and the test data characterized physical and chemical properties of soil samples were processed by path analysis method and sensitivity analysis method，respectively. The results showed that soil organic carbon content was affected by main driving factors in different ways and strength：soil pH value and alkalihydrolysable with strongly direct impacts；soil density and forest floor litter with strongly indirect impacts；soil moisture strongly influenced directly and indirectly；root biomass，available phosphorus content，readily available potassium and total porosity had the least effect on soil organic carbon content. In addition，the sensitivity order of those driving factors to soil organic carbon content was as follows：alkali-hydrolyzable nitrogen content > soil pH value > age of trees > forest floor litter >soil moisture >readily available potassium >root biomass > available phosphorus content >soil density >total porosity.