Figure legends:
Figure1 Schematic diagram of the grazing experiment plots. Dark color plots indicate systematic sampling plots. The grazing experiment plots (each ca. 4.4 hm2) were arranged in a randomized complete block design, which included four stocking rate treatments with three repeats of each stocking rate. The stocking rates were 0, 0.91, 1.82, 2.71 sheep·hm−2·half year−1representing no grazing (CK), light grazing (LG), moderate grazing (MG), and heavy grazing (HG), respectively.
Figure 2 The sample distribution for systematic sampling. The sample-plot size was 40 m×40 m, each square was 2.5 m×2.5 m, and the solid circles represent the sample points.
Figure 3 Dynamic changes of accumulated above-ground standing crop of shrubby and herbaceous plants during 2004-2017. CK, no grazing; LG, light grazing; MG, moderate grazing; HG, heavy grazing.
Figure 4 Triangular diagrams of the cover of shrubby plants, perennial grasses and other herbaceous plants. CK, no grazing; LG, light grazing; MG, moderate grazing; HG, heavy grazing.
Figure 5 Cover of four species under different stocking rates. Mean values (±SD; n = 9-15) of (A ) Artemisia frigida , (B)Kochia prostrata , (C) Caragana microphylla and (D)Ceratoides latens . Different lowercase letters indicate that grand means differ significantly between the grazing treatments (P < 0.05). CK, no grazing; LG, light grazing; MG, moderate grazing; HG, heavy grazing.
Figure 6 The quantitative characteristics of four species under different stocking rates. Mean values (±SD; n = 9-15) of (A-D )Artemisia frigida , (E-H) Kochia prostrata , (I-L)Caragana microphylla and (M-P) Ceratoides latens . Different lowercase letters indicate that grand means differ significantly between the grazing treatments (P < 0.05). CK, no grazing; LG, light grazing; MG, moderate grazing; HG, heavy grazing.
Figure 7 Correlation diagram of four shrubs and stocking rate gradient. A. fri , Artemisia frigida ; K. pro ,Kochia prostrata ; C. mic , Caragana microphylla ;C. lat , Ceratoides latens . CK, no grazing; LG, light grazing; MG, moderate grazing; HG, heavy grazing.