At each of the three sites in each habitat, three replicate plots (30 × 30 m) were randomly set and within each plot. In each site, 15 soil cores (diameter: 8 cm, height: 10 cm) were taken and combined into a composite sample in early September 2011 (3 plots per site × 5 samples per plot) (i.e. generally abundant precipitation occurred in September, and soil microbial activities were detected more easily)