Urban Street Trees and Tropical Microclimate Regulation: A Review of Ecosystem Services and Research Gaps

Abstract

Globally, street trees have become essential in improving environmental sustainability in rapidly urbanizing areas. This review investigates the contribution of street trees to urban microclimate in tropical regions, based on both empirical and simulation studies. With the guidance of the PRISMA framework, a systematic review of 48 peer-reviewed studies published between 2000 and 2025 was carried out using both Scopus and Google Scholar databases. Findings show that Street trees support urban thermal regulation by lowering ambient air temperature by 1–3 °C, and up to about 8 °C under dense canopy conditions, while achieving even greater reductions in mean radiant temperature through shading of people and urban surfaces. This improves outdoor thermal comfort in tropical cities, enhances air quality by removing pollutants, and reduces the cooling energy demand of buildings. There remain gaps in the literature with specific regard to long-term field measurements, species-specific performance data, and the incorporation of street trees into frameworks for climate-resilient urban planning in the tropics. The review concludes that street trees in urban areas are important, and suggests improved design, research, and policy approaches to maximize their environmental advantages.