A SYSTEMATIC ANALYSIS OF TREE SPATIAL ARRANGEMENTS AND THEIR IMPACT ON URBAN THERMAL ENVIRONMENTS

Rapid urbanization and climate change have worsened the urban heat island (UHI) effect, underscoring the need for strategic vegetation placement to promote sustainable development. Although the cooling benefits of urban trees are well-recognised, the influence of different spatial arrangements on microclimate regulation remains fragmented. This review consolidates evidence on how tree placement strategies grouped, linear, and individual—impact microclimate, thermal comfort, and heat mitigation across various climatic zones. Following the PRISMA guidelines, we searched the Web of Science, Scopus, and Google Scholar databases for peer-reviewed articles published between 2015 and 2025. From an initial pool of 279 papers, 49 peer-reviewed articles were analysed, focusing on microclimate outcomes such as tree configuration types, climatic parameters, cooling metrics, and comfort indices. Results showed that grouped trees achieve the highest cooling, lowering ambient temperatures by up to 5°C through evapotranspiration and canopy overlap. Linear tree arrangements effectively cool corridors, reducing surface temperatures by 2-4°C along pathways. Individual trees provide targeted cooling, especially when positioned 5-10 meters from buildings, leading to indoor cooling reductions of 10-15%. Research has been primarily conducted in East Asia (38%), with notable gaps in South Asia and Africa. Tree configuration plays a significant role in microclimate regulation, influencing thermal outcomes through shading, evapotranspiration, and wind flow modifications. This review goes beyond thermal outcomes to identify critical implementation challenges, highlighting urgent gaps in translating evidence into practice. This review provides a framework for urban planners to optimise the placement of trees. Future research should investigate the long-term impacts, species responses, and integration of green infrastructure.