## 2 Study Area and Dataset
### Dataset
#### 2.2.1 Meteorological Forcing and Land Surface Initial Conditions for the Biome-BGC Model
Then, the linear interpolation model and the Michaelis-Menten equation were used to fill small gaps (less than 2 h) and large gaps in the time series, respectively [36]. Subsequently, daytime ecosystem respiration was calculated using the Lloyd and Taylor method combined with nighttime observations [37]. Finally, GPP was estimated as the difference between daytime NEE and ecosystem respiration. (4) The distribution map of alpine grassland was derived from the digitized 1:1 million vegetation map of the TP compiled by Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (Figure 1). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**No.** & **Ecophysiological Parameters** & **Symbol** & **Units 1** & **PDF 2** & **Source** \\ \hline
1 & Transfer growth period as fraction of growing season & TGGS & proportion & U(0.135, 0.45) & [PERSON] [38] \\
2 & Lateral infection of growing season & LGS & proportion & U(0.135, 0.405) & [PERSON] et al. [21] \\
3 & Annual whole plant mortality fraction & WPM & 1 year & U(0.05, 0.15) & [PERSON] et al. [9] \\
4 & Annual rate mortality fraction & PM & 1 year & / & / \\
5 & New fine root C: new I & FBC1C & ratio & U(0.081, 2.19) & [PERSON] et al. [9] \\
6 & Current growth proportion & CCP & proportion & U(0.025, 0.75) & [PERSON] et al. [9] \\
7 & CN ratio of leaves & CN\({}_{\rm had}\) & NgC\({}_{\rm KgN}\) & N(2.85, 8.6) & [PERSON] et al. [9] \\
8 & CN ratio of leaf litter & CN\({}_{\rm lie}\) & NgC\({}_{\rm KgN}\) & N(45, 1) & [PERSON] et al. [9] \\
9 & CN ratio of fine roots & CN\({}_{\rm lie}\) & NgC\({}_{\rm KgN}\) & N(50, 19) & [PERSON] et al. [9] \\
10 & Leaf litter table proportion & Lu\({}_{\rm had}\) & DDM & 1-\({}_{\rm card}\)+\({}_{\rm lag}\) & / \\
11 & Leaf litter cellulose proportion & I\({}_{\rm end}\) & DDM & N(0.23, 0.077) & [PERSON] et al. [9] \\
12 & Leaf litter ring ignition proportion & I\({}_{\rm leg}\) & DDM & N(0.009, 0.043) & [PERSON] et al. [9] \\
13 & Fine root nodule proportion & FR\({}_{\rm had}\) & DDM & 1-FR\({}_{\rm orb}\)+\({}_{\rm lag}\) & / \\
14 & Fine root cellulose proportion & FR\({}_{\rm had}\) & DDM & (0.073, 0.495) & [PERSON] et al. [9] \\
15 & Fine root lignin proportion & FR\({}_{\rm had}\) & DDM & (0.095, 0.361) & [PERSON] et al. [9] \\
16 & Canopy water interception coefficient & W\({}_{\rm int}\) & 1/LAJ(day & U(0.018, 0.032) & [PERSON] et al. [9] \\
17 & Canopy light extinction coefficient & LEC & DDM & N(0.48, 0.13) & [PERSON] et al. [9] \\
18 & All-sided to predicted leaf area ratio & LAJ\({}_{\rm dep}\) & DDM & U(1, 3) & [PERSON] et al. [9] \\
19 & Canopy average specific leaf area & A\({}_{\rm l}\) & m\({}^{2}\)/AgCl & N(49, 16) & [PERSON] et al. [9] \\
20 & Ratio of shaded SL-c.unit SL-c.unit SL-c.unit SL-c.unit & DDM & (11, 3) & [PERSON] et al. [9] \\
21 & Percent of leaf N in Rubisco & PLNR & DDM & U(0.075, 0.225) & [PERSON] et al. [9] \\
22 & Maximum stomatal conductance & G\({}_{\rm max}\) & m/s & (0.0025, 0.0075) & [PERSON] et al. [9] \\
23 & Cutricular conductance & G\({}_{\rm card}\) & m/s & (0.0175, 0.02) & / \\
24 & Boundary layer conductance & G\({}_{\rm det}\) & m/s & U(0.02, 0.06) & [PERSON] et al. [9] \\
25 & Leaf water potential: start of conductance reduction & LNP\({}_{\rm l}\) & MPa & U(-1.27, -0.2) & [PERSON] et al. [9] \\
26 & Leaf water potential: complete conductance reduction & LNP\({}_{\rm l}\) & MPa & U(-4, -1.3) & [PERSON] et al. [9] \\
27 & Vapor pressure deficit: start of conductance reduction & VPD\({}_{\rm l}\) & Pa & U(700, 1500) & [PERSON] et al. [9] \\
28 & Vapor pressure deficit: complete conductance reduction & VPD\({}_{\rm l}\) & Pa & U(2000, 12000) & [PERSON] et al. [9] \\ \hline \hline \end{tabular}  
* 1 DIM: dimensionless. 2U(min, max): uniform distribution, N/mean, standard deviation): normal distribution, SLA, specific leaf area.  
\end{table} 
Table 1: Ecophysiological parameters of the Biome-BGC model for the type of C3 grass.