# Impact of Natural and Human Factors on Dryland Vegetation in Eurasia from 2003 to 2022
## 3 Results
### Spatiotemporal Patterns of Natural Factors in Eurasian Drylands  
From 2003 to 2022, the mean annual temperature (MAT) and atmospheric vapor pressure deficit (VPD) of the Eurasian drylands significantly increased at rates of 0.04 \({}^{\circ}\)C yr\({}^{-1}\) (\(p<0.01\)) and 0.003 K Pa yr\({}^{-1}\) (\(p<0.01\)), respectively (Figure 4a,d). The trends in soil moisture (SM) and mean annual precipitation (MAP) did not pass statistical significance tests (\(p>0.05\)) (Figure 4b,c). In contrast, terrestrial water storage (TWS) experienced significant decreases at rates of 4.45 mm yr\({}^{-1}\) (\(p<0.01\)) (Figure 4e). Spatially, from 2003 to 2022, over 38.88 % of the Eurasian drylands exhibited a significant increasing trend in MAT (Figure 5a), with particularly notable increases in WCE (West and Central Europe), EEU (E. Europe), the MED (Mediterranean), WCA (W. C. Asia) and ARP (Arabian Peninsula) (Table 4). In these regions, MAT increased at a rate higher than 0.05 \({}^{\circ}\)C yr\({}^{-1}\) (Table 4). MAP increased in more than 58.24% of the Eurasian drylands (Figure 5b), primarily located in ESB (E. Siberia: 4.82 mm yr\({}^{-2}\)) and  
Figure 4: Temporal trends in the mean annual temperature (MAT, (**a**)), mean annual precipitation (MAP, (**b**)), soil moisture (SM, (**c**)), vapor pressure deficit (VPD, (**d**)) and terrestrial water storage (TWS, (**e**)) in Eurasian drylands during 2003–2022, respectively. Solid (dashed) lines indicate significant (insignificant) regressions (\(p<0.05\), the Student’s \(t\)-test). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Variables** & **NDVI (10\({}^{-2}\) yr\({}^{-1}\))** & \
\begin{tabular}{c} **GPP** \\ **(10\({}^{-2}\) g C m\({}^{-2}\) yr\({}^{-2}\))** \\ \end{tabular} &
\begin{tabular}{c} **LAI** \\ **(10\({}^{-2}\) Wm\({}^{-2}\)\(\mu\)m\({}^{-1}\)sr\({}^{-1}\)yr\({}^{-1}\))** \\ \end{tabular} \\ \hline WCE & 0.12 * & 0.06 & 0.06 * \\ EEU & \(-\)0.02 & 0.01 & 0.003 \\ MED & 0.16 * & 0.16 * & 0.09 * \\ WSB & 0.01 & 0.05 & 0.02 \\ ESB & 0.19 * & 0.20 * & 0.09 * \\ WCA & 0.05 & 0.06 * & 0.03 * \\ ECA & 0.12 * & 0.08 * & 0.04 * \\ TIB & 0.07 * & 0.05 * & 0.03 * \\ EAS & 0.29 * & 0.29 * & 0.16 * \\ ARP & 0.10 * & 0.06 * & 0.05 * \\ SAS & 0.36 * & 0.31 * & 0.17 * \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The linear regression coefficients for normalized difference vegetation index (NDVI), gross primary productivity (GPP) and solar-induced chlorophyll fluorescence (SIF) during 2003–2022 in WCE (West and Central Europe), EEU (E. Europe), ME (Mediterranean), WSB (W. Siberia), ESB (E. Siberia), WCA (W. C. Asia), ECA (E. C. Asia), TIB (Tibet Plateau), EAS (E. Asia), ARP (Arabian Peninsula) and SAS (S. Asia). The symbol \({}^{\prime\prime\prime\prime}\) indicates that the linear regression coefficient has passed the significance test with \(p<0.05\) (the Student’s \(t\)-test). SAS (S. Asia: 6.97 mm yr\({}^{-2}\)) (Table 4). However, regions exhibiting a decreasing trend in MAP were primarily situated in WCE (\(-\)1.49 mm yr\({}^{-2}\)), EEU (\(-\)0.79 mm yr\({}^{-2}\)), the MED (\(-\)0.79 mm yr\({}^{-2}\)), WCA (\(-\)1.47 mm yr\({}^{-2}\)) and TIB (Tibet Plateau: \(-\)3.88 mm yr\({}^{-2}\)) (Table 4). Except for ESB, TIB and SAS, 57.71% of the Eurasian drylands experienced a decreasing trend in SM over this period (Figure 5c). Meanwhile, VPD significantly increased in 47.96% of the Eurasian drylands (Figure 5d). In WCE (0.005 K Pa yr\({}^{-1}\)), EEU (0.006 K Pa yr\({}^{-1}\)), the MED (0.005 K Pa yr\({}^{-1}\)) and WCA (0.006 K Pa yr\({}^{-1}\)) (Table 4), the increasing trend in VPD was higher than in other regions. The decreasing trend in TWS was significant in the Eurasian drylands (55.80%) (Figure 5e), mainly concentrated in the WCE (\(-\)1.05 mm yr\({}^{-1}\)), WCA (\(-\)0.88 mm yr\({}^{-1}\)) and EAS (E. Asia: \(-\)0.84 mm yr\({}^{-1}\)).