Figure legends
Figure 1: The effects of grazing intensity on plant aboveground
biomass, belowground biomass, plant community carbon and nitrogen
content. Different lowercase letters indicate significant differences
between means at p < 0.05. Error bards are ± SE, Codes
of different treatments are as follows: CK, control/no grazing; LG,
light grazing; MG, moderate grazing; HG, heavy grazing.
Figure 2: The effects of grazing intensity and month on plant
aboveground biomass and biomass of plant functional groups. Each panel
represents a different grouping of plant biomass. Different lowercase
letters indicate significant differences between means at p< 0.05. Error bards are ± SE, and the lines in panels b-e show
the biomass of each plant functional group during the 2020 growing
season. Codes of different treatments are as follows: CK, control/no
grazing; LG, light grazing; MG, moderate grazing; HG, heavy grazing.
Figure 3: The effects of grazing intensity on soil nutrients.
Different lowercase letters indicate significant differences between
means at p < 0.05. Error bars are ± SE. Codes
of different treatments are as follows: CK, control / no grazing; LG,
light grazing; MG, moderate grazing; HG, heavy grazing.
Figure 4: Monthly dynamics of ecosystem fluxes. Panels
show the mean value (±SE) of net exchange of ecosystem
CO2 (a, NEE), ecosystem respiration (b, ER), gross
ecosystem productivity (c, GEP) and soil respiration (d, SR) in the
growing season (June-October) of 2020. The inset reflects the
differences between treatments in the 2020 growing season, where
positive and negative values represent net carbon release and uptake by
the ecosystem and do not indicate the magnitude of the values. Different
lowercase letters indicate significant differences between treatments
(p < 0.05), Codes of different treatments are the same
as in Figure 3.
Figure 5: Biplot of ecosystem carbon exchange (NEE, ER, GEP,
SR) from redundancy analysis (RDA) for plant factors (a) and soil
factors (b). GLM analysis was used to study the contribution of the
plant and soil factors to the net exchange of ecosystem
CO2 (c, NEE), ecosystem respiration (d, ER), gross
ecosystem productivity (e, GEP) and soil respiration (f, SR). a-b,
Ecosystem carbon exchange is represented as red lines with arrows; plant
factors (a) and soil factors (b) are represented as blue lines with
arrows. The length of the line indicates the magnitude of the
correlation between the explanatory variable and ecosystem carbon
exchange. The angle between the lines indicates the correlation between
the variables, and the angle between the red and blue arrows is less
than 90° for positive correlations. Codes of different plant factors (a)
are as follows: AGB, aboveground biomass; BGB, belowground biomass; PG,
perennial grass biomass; AB, annual and biennial plant biomass; PF,
perennial forb biomass; SS, shrub and semi-shrub biomass; PTC, plant
total carbon; PTN, plant total nitrogen; C/N, the ratio of total plant
carbon content to total plant nitrogen content. Codes of different soil
factors (b) are as follows: TC, total carbon; TN, total nitrogen; TP,
total phosphorus; SOC, organic carbon; AN, ammonium nitrogen; NN,
nitrate nitrogen; AP, available phosphorus; MBC, microbial biomass
carbon; MBN, microbial biomass nitrogen. c-f, Importance of individual
environmental variables across models for ecosystem carbon exchange is
shown for each indicator as variable importance weighted by % of
R2.
Figure 6: Structural equation models (SEM) examining the
standard total effects of plant and soil factors on Ecosystem carbon
exchange under different grazing intensities. Boxes stand for measured
variables in the model. Standardized path coefficients are given. Solid
black lines represent positive paths (p < 0.05), solid
red lines represent negative paths (p < 0.05), and
dotted black arrows represent non-significant paths (p> 0.05).