Fig 1.
Location map of the study area of experimental plots on L. chinensis grassland.
The meadow steppe and typical steppe in Inner Mongolia regions of China are mainly dominated by L. chinensis.
Table 1.
L. chinensis plant functional traits used in this research.
Fig 2.
Effect of overgrazing on the height of L. chinensis individuals in natural grassland.
PH was significantly affected by grazing according to ANOVA testing (F = 81.97, P<0.001).
Fig 3.
Effect of overgrazing on L. chinensis individual plant aboveground biomass in natural grassland for: (a) the leaf biomass per individual (ANOVA results: F = 65.06, P<0.001), (b) the stem biomass per individual (F = 89.38, P<0.001), and (c) the aboveground biomass per individual, including leaf and stem (F = 83.78, P<0.001).
Fig 4.
Effect on aboveground biomass allocations of the overgrazing-induced variation in the size of L. chinensis individuals.
The leaf to stem biomass ratio of L. chinensis individuals is fitted to an exponential decay relation as a function of PH and AB. In the non-grazing group, the leaf to stem biomass ratio is significantly affected by PH (R = -0.78, P<0.001) and AB (R = -0.67, P<0.001). The leaf to stem biomass is also significantly affected by PH (R = -0.75, P<0.001) and AB (R = -0.64, P<0.001) in grazed plots. Overall, PH (R = -0.73, P<0.001) and AB (R = -0.62, P<0.001) significantly influence leaf to stem biomass (insets). The gray arrows in the figures show the shifts in the slopes of the exponential decay relations as a result of overgrazing.
Fig 5.
Effect on LMA of the variation in the size of L. chinensis individuals induced by grazing.
The relationship between LMA and PH was fitted to an equation representing an exponential rise to a maximum for both the non-grazing (R = 0.42, P<0.001) and grazing groups (R = 0.45, P<0.001). LMA was also significantly affected by PH (R = 0.51, P<0.001) for the combined data (inset).
Fig 6.
Allometric scaling of PFT and biomass in: (a) the leaves, (b) the stems, and (c) the whole L. chinensis plant.
The figures show the standardized major axis regressions (see also Table 1). The relationships between PFT and biomass in the leaves, stems, and whole plant are best described using a linear-equation-based SMA (P<0.01).
Table 2.
Relationships between aboveground biomass and the PFTs of L. chinensis individuals.
Table 3.
Standardized major axis regression slopes and confidence intervals (CIs) for log-log transformed relationships between aboveground biomass and PFTs of L. chinensis for non-grazing and long-term overgrazing groups.
Fig 7.
VIP values (mean + SD) of PFTs of L. chinensis individuals with respect to AB in: (a) non-grazing, (b) grazing, and (c) combined plots.
The dashed line in each figure represents a VIP value of 1.
Table 4.
The proportion of the AB variation in L. chinensis individuals explainable using morphological PFTs.
Fig 8.
Final results of the SEM analysis of the effects of overgrazing on: (a) AB, (b) LB, and (c) SB of L. chinensis individuals via PFT pathways.
Boxes and ellipses denote the observed and latent variables included in the models, respectively. Solid arrows denote the directions and effects that are significant (P<0.001, marked *** in the figure); dashed arrows represent the directions and effects that are not significant (P>0.05). Values associated with arrows represent standardized path coefficients. Estimates of the regression weights in the SEM analysis are given in S2 Table, S3 Table, and S4 Table.