Urban vegetation and thermal indicators dynamics to address heat-related challenges: A review framed by Local Climate Zones

The Local Climate Zone (LCZ) classification system has facilitated analysis of heat-related disparities in urban planning worldwide. The LCZ classes are differentiated by urban morphological parameters (e.g., impervious surface fraction, building heights, and building surface fraction). While vegetation-temperature relationships within the LCZ framework are not comprehensively documented, understanding this dynamic can improve interdisciplinary urban climate analysis. Using PRISMA guidelines, we analyzed 156 studies comparing thermal indicators across LCZs with varying vegetation cover, and 32 studies assessing vegetation characteristics influencing LCZ thermal indicators. Vegetation can help cool air and surface temperatures, with open and vegetated zones (LCZs 46, 9, A, and B) having 2.57 °C lower temperatures at daytime. Irrigation is very influential on vegetation cooling across LCZs, mainly in arid regions, while proximity to large water bodies can make even impervious zones cooler than open built-up zones farther from water. Heatwaves may compromise cooling in vegetated zones due to continuous heat advection from compact zones, and increased humidity from vegetation can occasionally reduce thermal comfort in cities from warm and humid climates. Street trees lower open zones thermal sensation by 5 °C, whereas green roofs and walls can improve the outdoor thermal comfort of compact zones by 0.53 °C. Broadleaf trees with dense canopies generally outperform pine species. Compact high-rise zones achieve optimal cooling through dense tree parks, but this benefit is limited to their immediate neighbors. Including knowledge on vegetation-temperature dynamics across LCZs can aid further integrated strategies towards urban climate resilience.