## 4 Results
### Transition of Vegetation Vulnerability during Different Periods in the MRB  
Table 6 shows the transition of vegetation vulnerability during different periods. From the base period to the near future period, under the SSP1-2.6, the mild vulnerability, moderate vulnerability, and severe vulnerability had the largest transition area into moderate vulnerability, severe vulnerability, and extreme vulnerability, respectively, with the area all over 1200 km\({}^{2}\). The transition area from extreme vulnerability to severe vulnerability was twice the area where extreme vulnerability remained unchanged. Under the SSP2-4.5, the mild vulnerability, moderate vulnerability, and severe vulnerability still had the largest transition area into moderate vulnerability, severe vulnerability, and extreme vulnerability, respectively, but the transition area increased 100 km\({}^{2}\) compared to the SSP1-2.6. The transition area of extreme vulnerability to severe vulnerability decreased by 50 km\({}^{2}\) compared to the SSP1-2.6. Under the SSP5-8.5, the transition area of mild vulnerability, moderate vulnerability to severe vulnerability, and extreme vulnerability increased more rapidly compared to the SSP1-2.6 and SSP2-4.5. The area of extreme vulnerability remained unchanged and was the largest compared to the SSP1-2.6 and SSP2-4.5.  
From the base period to the distinct future period, under the SSP1-2.6, the area of mild vulnerability transformed into moderate vulnerability unchanged and was almost the same as the area of unchanged mild vulnerability. Similarly, the area of moderate vulnerability transformed into mild vulnerability and was almost the same as the area of unchanged moderate vulnerability, but smaller than the area in which moderate vulnerability transformed into severe vulnerability. Compared with the base period to the near future period, the transition area of severe vulnerability to extreme vulnerability was much less, and the transition area of extreme vulnerability to severe vulnerability was a little less. Under the SSP2-4.5, compared with the base period to the near future period, the transition area of mild vulnerability to moderate vulnerability increased by about 800 km\({}^{2}\). The area transformed from moderate vulnerability to mild vulnerability decreased obviously, but the area from moderate vulnerability transformed to extreme vulnerability and increased by 139.41%. The area of unchanged extreme vulnerability increased by 37.73%. Under the SSP5-8.5, the vegetation vulnerability transition was similar to the SSP2-4.5. Compared with the base period to the near future period, the area of mild vulnerability, moderate  
Figure 5: LISA cluster of vegetation vulnerability for the near future period and distinct future period in the MRB.  
vulnerability, and severe vulnerability transformed to moderate vulnerability, severe vulnerability, and extreme vulnerability and all increased by about 100 km\({}^{2}\). In addition, the area of unchanged extreme vulnerability increased by 77.28% compared with the base period to the near future period.  
Under all scenarios, from the base period to the near future period or to the distinct future period, there was no transition between mild vulnerability and extreme vulnerability. From low to high emission scenarios, the area of unchanged vulnerability or less vulnerability gradually decreased, and the area transformed into higher vulnerability increased. From the near future period to the distinct future period, the transition to higher vulnerability became much more obvious, and the transition increased fast under a high emission scenario.