An improved method for assessing vegetation cooling service in regulating thermal environment: A case study in Xiamen, China

Quantitatively evaluating vegetation cooling service has become an important issue in current ecosystem service assessment, especially for urban area. Based on a previous method proposed on the energy exchanging theory, this study developed an improved method to generate a spatially explicit evaluation of the vegetation cooling service by introducing fractional vegetation cover (FVC) and the daily length of vegetation cooling service provision. Using remote sensing data from Landsat-8 and MODIS-Terra observations and field measurements from local meteorological stations, the method was successfully applied in Xiamen, a city located on the southeastern coast of China. The results showed that surface elevation and FVC had profound impacts on the length of vegetation cooling service provision and the vegetation cooling ability, respectively. For the vegetation surfaces of total 799.48 km(2) in Xiamen, the annual heat absorption was 2.73 x 10(9) MJ/a in 2015 with an average length of cooling service provision of 1954.04 h. A more reasonable spatial distribution of vegetation heat absorbing capacity can be found with the differences not only among different vegetation types but also within the same vegetation type. Thus, this study emphasized the impacts of vegetation coverage and cooling length on providing cooling service, which has practical implications for vegetation planning in urban areas.