Abstract: Global climate warming and intensified urbanization have altered the urban-rural environmental gradient, with consequence on the growth and adaptation processes of urban forest trees. To explore the differences in radial growth and ecological resilience of trees under varying degrees of urbanization, we established plots in forest parks within urban areas of Qingdao and in the rural area of Laoshan Mountain. A total of 342 trees and 626 cores (including 339 Pinus thunbergii and 287 Robinia pseudoacacia) were sampled. Using dendrochronological methods, we quantitatively analyzed the growth characteristics and responses of both species to extreme drought events (in both 1992 and 2015) under different urbanization intensities. The results showed that radial growth rates of both species were 1.87-2.75 mm·a^-1 and were generally lower in urban than those in rural areas (on average 1.6% to 4.7% lower). Both species exhibited a decreasing trend during recent years (2004-2020) relative to the past period (1980-2003), with a more significant decline in urban areas. P. thunbergii in urban areas showed significantly higher resistance (18.0%) than those in rural areas, suggesting stronger immediate tolerance to drought stress, whereas R. pseudoacacia displayed higher resistance (25.9%) in rural sites, indicating better adaptation to less urbanized environments. The recovery and resilience of both species in two areas showed relatively small differences, though P. thunbergii (1.34, 1.39) recovered slightly faster than R. pseudoacacia (1.00, 1.20), demonstrating that P. thunbergii has higher ecological resilience. Both resistance and recovery were significantly negatively correlated. P. thunbergii in urban sites exhibited a flatter trade-off curve and a wider range of recovery, reflecting a more flexible ecological adjustment under urban conditions. Overall, the combined effects of urbanization and climate warming have intensified drought stress, limited radial growth, and driven divergent adaptive strategies between resistance and recovery across tree species.

Key words: urbanization, extreme drought, ecological resilience, tree ring, radial growth