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.