The Role of Tree Crown Morphology in Regulating Microclimate in Urban Spaces

Abstract

Urban expansion has intensified the urban heat island (UHI) effect, exacerbating heat-related risks and energy demands. While urban vegetation, particularly trees, is recognized for its microclimate-regulating potential through shade and evapotranspiration, the specific roles of tree crown morphology and leaf area index (LAI) remain underexplored, with gaps in understanding species-specific interactions, climatic adaptability, and practical urban integration. This study analyzes how crown characteristics (size, shape, density, height) and LAI collectively influence microclimate regulation, offering actionable insights for urban planners. This research systematically evaluates 32 peer-reviewed sources and real-world applications by employing a qualitative synthesis of literature method of 21 studies and 11 case studies (2005–2024) from diverse climatic zones. Findings reveal that trees with expansive crowns and high LAI (>4) reduce ambient temperatures by 1.5–5°C, with dense canopies enhancing shading and evapotranspiration. However, challenges include measurement inaccuracies in crown morphology, spatial heterogeneity in LAI, and limited long-term data, particularly in tropical and arid regions. Practical implications emphasize strategic species selection (e.g., broad-canopy, high-LAI trees) and placement to optimize shading and airflow, alongside policy measures like mandatory greening in urban developments. The study’s originality lies in its integrative approach, bridging theoretical and empirical evidence to address UHI mitigation while advocating for human-centric, climate-responsive urban planning. By avoiding automated methodologies, this research underscores the need for community engagement and ethical, localized solutions to enhance urban livability and resilience.