Chiang Mai Journal of Science

In this paper experimental study has been conducted to evaluate the heat reduction potential of ambient air by vegetation. Nineteen types of plants were tested and classified as 1) perennial, 2) shrubs and 3) ground cover plants. The study plant production under actual environmental conditions showed that shadow area of perennial plants and ground cover crops were found to reduce the temperature by 2-5 °C. The results presented vegetation with moderately thick and clear foliage was found to block the sunlight by 200-600 W/m2-crown. Water use in crops typically is quantified by evapotranspiration rate (ET), which refers to the loss of water from the soil by evaporation and from the plant through transpiration. The capability to reduce atmospheric warming was shown the water consumption by plants at an average of 109-111 and 131-132 W/m2-crown while shrubs plants and ground cover crops used 68.8 and 94.4 W/m2-crown, respectively. Shade from plants with transparent leaves resulted to 17-18% lower sunlight concentration than plants with thick leaves with shade from perennial trees reducing atmospheric warming to about 500-700 W/m2-crown as compared to plants with transparent leaves (460-625 W/m2-crown) at the same time.