2.2 | Experimental design
A long-term grazing intensity experiment was established in 2004. We had
four grazing intensities: control (zero sheep-unit
ha-1 month-1, G0), light (0.15
sheep-unit ha-1 month-1, G0.15),
moderate (0.30 sheep-unit ha-1month-1, G0.30), and heavy grazing (0.45 sheep-unit
ha-1 month-1, G0.45) (Zhang et al.,
2021). Each treatment had three replicates. Under a complete randomized
block design, 12 plots, each with an area of 4.4 ha, were separated by
fences. Sheep with similar size were selected in advance and the grazing
period lasted from June 1 to November 30 every year.