Seasonal impacts of  urban morphology on vegetation carbon sequestration across urban functional blocks

Vegetation carbon sequestration (VCS) is widely recognized as an important nature-based solutions for offsetting urban carbon emissions. Although previous studies have shown that urban morphology may greatly impact VCS, few have examined the seasonal impacts of multidimensional urban morphology on VCS across urban units, particularly at the irregular urban functional block (UFB) scale. Here, we revealed the seasonal relationship between multidimensional urban morphology and VCS across different UFB types by combining random forest regression and Shapley additive explanation technology. A total of 20 features were defined to represent 3 dimensions of urban morphology: landscape composition, landscape configuration, and surface biophysical parameters. Taking Wuhan, China as an example, the results showed that the mechanisms underlying VCS responses to urban morphology were strongly dependent on seasons and UFB types. Urban morphology explained a higher share of VCS variations in spring, autumn, and winter, while landscape configuration played a more important role in summer. In residential, industrial, commercial, traffic, and public service blocks, landscape composition explained most seasonal VCS variations, particularly through the coverage of impervious surfaces and low green vegetation. In contrast, in cropland and green space blocks, both landscape configuration and composition played substantial roles from summer to winter. Moreover, all urban morphological features showed seasonal threshold effects on VCS across different UFB types, with positive contributions occurring within specific threshold ranges. Overall, this study advances a planning-oriented framework that supports the implementation of nature-based solutions of vegetation for urban decarbonization by linking urban morphology optimization with ecosystem carbon sequestration processes.