Tree species diversity and identity effects on soil properties in the Huoditang area of the Qinling Mountains, China

Soil properties, such as carbon stock, nitrogen stock, cation exchange capacity (CEC), bulk density (BD), and pH, may have a different status when the forest type changes. We were interested in how tree species identity and diversity affect soil properties. Forest soil profiles were sampled at a fixed depth (0-10, 10-20, 20-40, and 40-60 cm). The abovementioned soil properties were compared by species to demonstrate the influence of tree species identity. We calculated the true Shannon diversity index and evaluated tree species diversity effects on soil properties. We found that the soil BD, CEC, and pH were all influenced by tree species identity. Tree species diversity only showed a negative effect on soil carbon stock; in contrast, a positive effect on soil nitrogen stock in the 0- to 10-cm soil layer was found. High diversity could lead to a change in the soil nutrient conditions in the form of C/N ratio decreases. In contrast, tree species diversity had a marginal effect on the soil BD, pH, and CEC. We concluded that tree species identity was a strong driver of soil properties in the study area, especially in the 0- to 10-cm layer, and that tree species diversity only altered the soil nutrient condition to some extent.