## 2 Results
### Spatial and Temporal Dynamic Distribution of Grassland AGB in Xinjiang
#### 2.2.2 Temporal Changes in Grassland AGB in Xinjiang from 2000 to 2022  
The temporal distribution of the mean grassland AGB in Xinjiang from 2000 to 2022 is shown in Figure 3. The AGB of six grassland types, including lowland meadow, temperate  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Grassland Types** & \begin{tabular}{c} **Mean Value** \\ **(g\(\cdot\)m\({}^{-2}\))** \\ \end{tabular} & \begin{tabular}{c} **Maximum Value** \\ **(g\(\cdot\)m\({}^{-2}\))** \\ \end{tabular} & \begin{tabular}{c} **Minimum Value** \\ **(g\(\cdot\)m\({}^{-2}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Standard** \\ **Deviation (g\(\cdot\)m\({}^{-2}\))** \\ \end{tabular} &
\begin{tabular}{c} **Coefficient** \\ **Variable** \\ \end{tabular} \\ \hline Lowland meadow (M1) & 95.69 & 107.59 & 87.50 & 5.20 & 0.05 \\ Montane meadow (M2) & 137.21 & 152.77 & 122.18 & 6.94 & 0.05 \\ Alpine meadow (M3) & 128.91 & 140.02 & 120.89 & 4.98 & 0.04 \\ Meadow (M) & 120.60 & 152.77 & 87.50 & 18.95 & 0.16 \\ Temperate meadow steppe (S1) & 119.56 & 135.62 & 110.52 & 5.86 & 0.05 \\ Temperate steppe (S2) & 107.64 & 116.65 & 102.00 & 3.20 & 0.03 \\ Temperate desert steppe (S3) & 95.91 & 102.49 & 90.41 & 3.08 & 0.03 \\ Alpine steppe (S4) & 91.33 & 96.59 & 85.10 & 3.37 & 0.04 \\ Steppe (S) & 103.61 & 135.62 & 85.10 & 11.72 & 0.11 \\ Temperate steppe desert (D1) & 90.51 & 96.03 & 83.76 & 3.08 & 0.03 \\ Temperate desert (D2) & 88.19 & 97.90 & 82.17 & 4.32 & 0.05 \\ Alpine desert (D3) & 68.09 & 73.50 & 63.51 & 2.81 & 0.04 \\ Desert (D) & 82.27 & 97.90 & 63.51 & 10.70 & 0.13 \\ \hline \end{tabular}
\end{table}
Table 1: Descriptive statistics of grassland AGB in Xinjiang from 2000 to 2022.  
Figure 2: The relationship between the measured grassland AGB and the estimated grassland AGB in Xinjiang. (**a**) Linear correlation. (**b**) Violin plot.  
steppe desert, temperate desert, alpine desert, temperate desert steppe, and alpine steppe, increased significantly in Xinjiang, with lowland meadow AGB increasing significantly and at the fastest rate (\(\theta\) = 0.65, \(p\) < 0.01), followed by alpine steppe AGB and temperate desert AGB (\(\theta\) = 0.37, \(p\) < 0.01), and desert grassland AGB (\(p\) < 0.05). Additionally, montane meadow AGB showed a slight decrease, while other grassland types showed an increasing trend, suggesting that the grassland AGB generally increased from 2000 to 2022.  
According to the results of the MK mutation test (Table 2), there was a difference in the timing of AGB mutation. We found that AGB of the alpine grasslands AGB (alpine meadow, alpine steppe, and alpine desert) mutated in 2014, while the AGB of lowland meadow, temperate desert steppe, and temperate steppe desert mutated in 2009. Additionally, temperate steppe and temperate desert had two mutation points, whereas montane meadow and temperate meadow steppe had four mutation points, with the highest CV (0.05) and high volatility.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Grassland Types** & **Year of Mutation** \\ \hline Lowland meadow (M1) & 2009 \\ Montane meadow (M2) & 2004/2010/2014/2022 \\ Alpine meadow (M3) & 2014 \\ Temperate meadow steppe (S1) & 2005/2007/2010/2013 \\ Temperate steppe (S2) & 2003/2014 \\ Temperate desert steppe (S3) & 2009 \\ Alpine steppe (S4) & 2014 \\ Temperate steppe desert (D1) & 2009 \\ Temperate desert (D2) & 2006/2009 \\ Alpine desert (D3) & 2014 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mutation time of grassland AGB.  
Figure 3: Characteristics of temporal changes in different grassland AGB from 2000 to 2022.