## 3 Results
### Analysis of EQI and USI in City-Level  
In this study, the EQI changes of each city in the three major urban agglomerations were also calculated, as shown in Figure 6. Most of cities' EQI in the three major urban agglomerations has decreased. In addition, the pattern of EQI in the three major urban agglomerations are not consistent, with Beijing, Tianjin, and Hebei having the worst balance. Zhangjiakou in the BTH, Zhoushan in the CYRD, and Zhaoqing in the PRD have improved \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**BTH**} & \multicolumn{6}{c}{**CYRD**} \\
**LC Type** & **Cr** & **Fr** & **Gr** & **Wt** & **Br** & **CI** & **EI** & **Total** & **Cr** & **Fr** & **Gr** & **Wt** & **Br** & **CI** & **EI** & **Total** \\ \hline Cr & 1130 & 4 & 5 & 43 & 0 & 436 & 1501 & 3119 & 4473 & 11 & & 91 & 2 & 1071 & 4693 & 10,611 \\ Fr & 7 & 25 & 0 & & & 1 & 9 & 42 & 79 & 89 & 0 & 4 & & 5 & 40 & 217 \\ Gr & 19 & 0 & 14 & 1 & 1 & 4 & 12 & 51 & & & & & & 0 \\ Wt & 38 & 0 & 0 & 102 & 1 & 39 & 138 & 318 & 178 & & & 660 & 1 & 34 & 193 & 1066 \\ Br & 1 & 0 & 0 & 2 & 1 & 2 & 7 & 13 & & & & & 0 & 1 & 1 \\ CI & 4 & & & 7 & & & 2492 & & 2503 & 2 & & & 12 & & 2855 & & 2869 \\ EI & 4 & & & 15 & & & 1603 & 1622 & 2 & & & 7 & & & 2245 & 2255 \\ Total & 1203 & 29 & 19 & 170 & 3 & 2974 & 3270 & 7668 & 4735 & 100 & 0 & 774 & 3 & 3966 & 7441 & 17,019 \\ \multicolumn{10}{c}{PRD} \\ LC Type & Cr & Fr & Gr & Wr & Br & CI & EI & Total & & & & & & & & & \\ Cr & 2030 & 75 & 5 & 64 & 4 & 1114 & 617 & 3909 & & & & & & & \\ Fr & 146 & 257 & & & & & 44 & 38 & 485 & & & & & & \\ Gr & 6 & & 1 & 1 & 16 & 9 & 33 & & & & & & & & \\ Wt & 348 & 1 & 1 & 535 & 5 & 168 & 124 & 1182 & & & & & & & \\ Br & & & & & 0 & & 1 & 1 & & & & & & & \\ CI & 2 & & & 7 & & 2102 & & & 2111 & & & & & & & \\ EI & & & & 1 & & & 460 & 461 & & & & & & & \\ Total & 2532 & 333 & 7 & 608 & 9 & 2532 & 1249 & 8182 & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The LC transition statistics from 2001 to 2020 in three urban agglomerations. (The corresponding relationship between each LC category and its abbreviation are as follows: Crop (Cr); Forest (Fr); Grassland (Gr); Water (Wt); Barren (Br); Impervious of Core region (CI); Impervious of Expansion region (EI)). their EQI mainly due to the intervention of projects such as the \"Water Containment Forest\", the \"Three North Protection Forest Program\", and the PRD Ecological Protection Belt. Another important reason for the ecological improvement is that these cities are farther away from urban land expansion centers and have less ecological pressure. In addition, cities with high EQI have also attracted attention. Cities such as Chengde, Zhaoqing, Huizhou, Wenzhou, and Hangzhou have high forest vegetation cover, rich natural and biological resources, great initial ecological quality, low impact by urbanization, and national ecological barrier protection projects that together guarantee ecological security. As for the cities whose EQI decreased, urban expansion and its negative effects are the main reasons. For example, in Tangshan City in the BTH, Taizhou City and Jiaxing City in the CYRD, and Zhuhai City and Zhongshan City in the PRD, the main causes of ecological degradation are reduced ecological resilience due to reduced vegetation and urbanization-induced land use changes, high levels of pollution, and industrialization. Another reason why the EQI of each city varies greatly may be the influence of economic development of cities. Shanghai already had a high level of urbanization in 2001, and the spreading effect of urbanization has allowed ecological degradation to occur mainly in its periphery, in Suzhou and Jiaxing. The results regarding the intensity of urban expansion, EQI changes, and the Urban Synergistic Index (USI) are presented in Table S3. As illustrated in Figure 7, all cities in the CYRD exhibit a higher overall intensity of urbanization compared to those in BTH and PRD.