Authors’ Contributions
D.H.X. and X.W.F. conceived the study and designed the methodology;
W.B.M., X.J.W. and R.Y.Z collected and analyzed the data; D.H.X., J.L.Y.
and G.Q.Y. led the writing of the manuscript. All authors contributed
critically to the drafts and gave final approval for publication.
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List of Figures
Fig. 1. Aboveground biomass of grasses (a, b) and community (c, d) in
native grasslands and active restoration grasslands. Various
alphabetical characters depict significant difference atP <0.05.
Fig. 2. Pn (net photosynthetic rate) (a, b), gs (stomatal
conductance) (c, d), WUEi (instantaneous water use efficiency)
(e, f) and Ci (intercellular CO2 concentration)
(g, h) of grasses in native grasslands and active restoration
grasslands. Various alphabetical characters depict significant
difference at P <0.05.
Fig. 3. Relationship of Pn (net photosynthetic rate) (a), gs(stomatal conductance) (b), WUEi (instantaneous water use
efficiency) (c) and Ci (intercellular CO2concentration) (d) with aboveground biomass of grasses in native
grasslands and active restoration grasslands.
Fig. 4. Plant N (a) and P concentration (b) in native grasslands and
active restoration grasslands. Various alphabetical characters depict
significant difference at P <0.05.
Fig. 5. Relationship of plant N (a) and P concentration (b) with
aboveground biomass in native grasslands and active restoration
grasslands.
Fig. 6. Principal components analysis (PCA) for all measured
photosynthesis related parameters and N and P concentration alongside
degradation in native grasslands (a) and active restoration grasslands
(b). AGB (aboveground biomass), Pn
(net photosynthetic rate),Ci (intercellular CO2 concentration), gs(stomatal conductance), and Tr (transpiration rate), WUEi(instantaneous water use efficiency), plant N (nitrogen concentration),
plant P (phosphorus concentration).
Fig. 7. Structural equation models (SEM) based on the effects of
degradation level of native grasslands and replanting time
of active restoration grasslands
on eco-physiological properties and AGB. Black and red arrows indicate
negative and positive relationships, respectively. The width of arrows
is proportional to the strength of path coefficients. As in other liner
models, R2 indicates the proportion of variance
explained and appears above every response variable in the model.
Significance levels are as follows:✱P <0.05,✱✱P <0.01,✱✱✱P <0.001. (a) native grasslands
(χ2/DF=0.843, P =0.537,
CFI=1.000, RMSEA=0.000; NFI=0.976; RFI=0.917) (b) active restoration
grasslands (χ2/DF=0.881, P =0.508, CFI=1.000 RMSEA=0.000;
NFI=0.985; RFI=0.947).