Study area and experimental design
The experimental site is located at Wulongchi Experiment Station (32°45′N, 111°13′E; 280–400 m a.s.l) in the Danjiangkou Reservoir area of Hubei province, China. The climate in this region is characterized by the subtropical monsoon, with mean temperature 15.7 ℃ (monthly averages of 27.3 ℃ in July and 4.2 ℃ in January.), and mean precipitation 749.3 mm (70% – 80% occur between April and October) (Cheng et al.2013; Zhang et al. 2016). The soil is classified as yellow-brown soil in Chinese soil classification or Haplic Luvisols in the USDA Soil Taxonomy. More detail information was reported in previous articles (e.g., (Cheng et al. 2013; Zhang et al. 2016).
The experiment used a random block design, three land use types (woodland, shrubland, cropland) were chosen from three adjacent transects. Each block was approximately 3 hm2 (600 m × 50 m) and the distance between adjacent blocks was larger than 100m. Comprehensive surveys of soil and vegetation were conducted in winter (Dec. 2017) and summer (Jul. 2018) to detect the structure and seasonal dynamics of the microbial community and ecosystem functioning. All samples were taken at the same location to ensure the comparability (e.g., similar topography and soil types) of the soil sampling plots among the three land use types. Each sampling plot, six soil cores from 0 - 10 cm were taken using a 5 cm-diameter soil auger, and then thoroughly mixed and pooled as one complete soil sample after removing visible gravel and plant litter or detritus. Soil samples were immediately sieved through a 2.0 mm sieve and then separated into two parts: one stored in -20 ℃ for physical and chemical analysis, and the other one was stored at -80 ℃ for molecular analyses.