2.2 | Experimental design
For the study, 36 soil samples were collected at random from different forest types (NA, C. oleifera new afforestation; GNA,Gardenia jasminoides + C. oleifera new afforestation; GLF,G. jasminoides + C. oleifera low-yielding forest; and LF,C. oleifera low-yielding forest) in April 2019, with nine soil samples collected from each forest type. In each block, a south to north topographic profile was selected, and the sampling plots were set in three slope positions at the base of the slope, on the midslope and the top of the slope. The angles of each of these were the same for each forest type. Stratified sampling was performed at different soil depths (0–20 cm, 20–40 cm, and 40– 60 cm) for each slope position, and three replicate plots were selected. Following collection, the samples were immediately frozen in liquid nitrogen, placed in a sterile plastic bag, labeled, transferred to the laboratory in a portable refrigerator on dry ice, and stored at –80 °C prior to bacterial community analysis.