Abstract
This study explored effects of urban greenspace on improving atmospheric environment, which is concerned with $CO_2$, SO$_2$ and NO$_2$ uptake, and with reduction of summer air temperatures. The site of this study was focused on Jung-gu in Seoul. Tree density and cover were 1.1 trees/100 $m^2$ and 12.5% respectively for the study area except forest lands. Atmospheric purification by greenspace was associated with changes in tree cover per unit area of each land use type. The mean $CO_2$ storage by woody plants was 19.4t/ha, and annual uptake averaged 2.2t/ha/yr for $CO_2$, 1.9kg/ha/yr for SO$_2$ and 5.0kg/ha/yr for NO$_2$. Entire tree plantings in the study area played a significant role by annually offsetting $CO_2$ emissions of about 1,830t from fossil fuel consumption by 330 persons, SO$_2$ emissions of 1,620kg by 1,080 persons, and NO$_2$ emissions of 4,230kg by 450 persons. The summer air temperature was 3.6$^{\circ}C$ cooler at a location with 54% cover of woody plants and 4.5$^{\circ}C$ cooler at a forest site with 100% cover, compared to a place with no planting. A 10% increase of woody plant cover was estimated to decrease summer air temperature by approximately 0.6$^{\circ}C$ until a certain level of canopy cover. Analyzing data from the Automatic Weather Stations in Seoul revealed that increasing tree cover decreased mean air temperature for the summer season (Jun~Aug) in a nonlinear function. Woody plant cover was the best predictive variable of summer temperature reduction. The results from this study are expected to be useful in emphasizing the environmental benefits and importance of urban greenspace enlargement, and in urging the necessity for planting and management budgets.
