Effects of species composition and species diversity on soil properties in warm temperate forest ecosystems of Dongling Mountainous region, Beijing

Two biodiversity indices (Simpson index and McIntosh index) were calculated based on vegetation data on seven typical warm temperate forest ecosystems in Dongling Mountainous region of Beijing City. Such parameters of soil property as pH value, soil bulk density, TKN, total C, C/N ratio, NH4+-N and NO3--N concentrations in the seven forest ecosystems were determined. The results showed that the soil pH values, total C concentrations and the C/N ratios of the seven forest ecosystems did not differ from each other, while soil bulk density, TKN, NH4+-N and NO3--N concentrations differed significantly, indicating that species composition significantly influenced the soil properties. The results of correlation showed that: 1. the two indices of tree layers were negatively correlated with soil bulk density; 2. the two indices of shrub layers were negatively correlated with soil NH4+-N concentration and 3. the two indices of herb layers were negatively correlated with soil NO3--N concentration, suggesting that soil bulk density decreased with the increase of species diversity of tree layers; and soil NH4+-N and NO3--N concentrations decreased with the increase of biodiversity of shrub layer and herb layer, respectively. Our results supported the hypothesis that species composition and species diversity in forest ecosystems would also have significant influences on soil properties, being similar to that of studies on grassland ecosystems.