2.1 | Site description
The experimental site was at a forest farm in Tangjiapu (111.844347°E, 29.188179°N), Dingcheng District, Changde, Hunan Province, China. The regional climate is subtropical monsoon, with a mean annual total rainfall of 1,200–1,900 mm, mean annual temperature of 16.7 °C, and the soil at the experimental site is quaternary red clay with a pH of 5.