Cooling effect to mitigate Urban Heat Island by Pterocarpus indicus, Swietenia macrophylla and Samanea saman In Bandung, West Java Indonesia

Abstract

Urban Heat Island (UHI) has been detected in Bandung since 2001 and it can be mitigated by planting trees such as Pterocarpus indicus (angsana), Swietenia macrophylla (mahogany), and Samanea saman (trembesi). This research was conducted to measure temperature reduction by those road side trees at seven locations. Parameters were tree characteristics including shape and area of canopy, Plant Area Index (PAI), and leaf morphology (shape and arrangement), air temperature, relative air humidity, transmissivity, and surface temperature. Microclimate and edaphic data were measured in sunny day or partly cloudy. Data were analyzed using One-way ANOVA (Kruskal-Wallis test) to clarify significance differences among parameters in each tree species and measured reduction of discomfort index (dDI%). Air temperature in open area is 33.81±2.32°C, while surface temperature is 37.29±6.63°C. Result shows that trees have varies ability to decrease air and surface temperature. The highest reduction of air (A) and surface (S) temperature is shown by S. saman (A=3.80±1.21°C and S=10.49±2.84°C), then followed by S. macrophylla (A=3.10±1.94°C and S=5.64±5.51°C), and P. indicus (A=2.28±1.73°C and S=5.26±4.30°C). S. saman which has wide canopy with moderate leaf density can reduce air and surface temperature effectively, followed by S. macrophylla with narrow canopy and high leaf density; and P. indicus with narrow canopy with low leaf density. Thus, tree character with broad canopy and dense leaves such as S. saman can be recommended as shading tree to mitigate UHI in urban areas.