Measuring the spatial arrangement of urban vegetation and its impacts on seasonal surface temperatures

Abstract

Urban forestry is an important component of the urban ecosystem that can effectively ameliorate temperatures by providing shade and through evapotranspiration. While it is well known that vegetation abundance is negatively correlated to land surface temperature, the impacts of the spatial arrangement (e.g. clustered or dispersed) of vegetation cover on the urban thermal environment requires further investigation. In this study, we coupled remote sensing techniques with spatial statistics to quantify the configuration of vegetation cover and its variable influences on seasonal surface temperatures in central Phoenix. The objectives of this study are to: (1) determine spatial arrangement of green vegetation cover using continuous spatial autocorrelation indices combined with high-resolution remotely-sensed data; (2) examine the role of grass and trees, especially their spatial patterns on seasonal and diurnal land surface temperatures by controlling the effects of vegetation abundance; (3) investigate the sensitivity of the vegetation–temperature relationship at varying geographical scales. The spatial pattern of urban vegetation was measured using a local spatial autocorrelation index—the local Moran’s Iv. Results show that clustered or less fragmented patterns of green vegetation lower surface temperature more effectively than dispersed patterns. The relationships between the local Moran’s Iv and surface temperature are evidenced to be strongest during summer daytime and lowest during winter nighttime. Results of multiple regression analyses demonstrate significant impacts of spatial arrangement of vegetation on seasonal surface temperatures. Our analyses of vegetation spatial patterns at varying geographical scales suggest that an area extent of ˜200 m is optimal for examining the vegetation–temperature relationship. We provide a methodological framework to quantify the spatial pattern of urban features and to examine their impacts on the biophysical characteristics of the urban environment. The insights gained from our study results have significant implications for sustainable urban development and resource management.

Examining Urban Impervious Surface Distribution and Its Dynamic Change in Hangzhou Metropolis

“…In addition, urbanization can result in UHI, and spatial patterns of different ISA expansion directions can intensify the UHIs in those directions [9,10,47,62,63]. Therefore, the spatial patterns of ISA expansion in this research will be valuable for use in examining UHI spatial patterns in Hangzhou metropolis.…”

Understanding the Impact of Urbanization on Surface Urban Heat Islands—A Longitudinal Analysis of the Oasis Effect in Subtropical Desert Cities

“…Increased impervious surface fractions in cities, including buildings and infrastructure, are the main causes of the UHI effect, which impacts energy use, water consumption, air quality, and human health [2]. Since its first discovery by Luke Howard in the early 1800s in London [3], numerous UHI studies have been conducted in various cities around the globe [4][5][6][7][8][9][10][11][12][13][14].…”

Rooftop Surface Temperature Analysis in an Urban Residential Environment

“…Using datasets such as ASTER, Quickbird, and Landsat ETM+, researchers show that proximity to asphalt surfaces and dark roofs and the pattern of impervious surfaces increase land surface temperature and denser nearby vegetation cools surfaces [36,37]. For cooling urban areas, Fan and Myint [38] examined the utility of spatial autocorrelation indices in characterizing spatial arrangement of urban landscape at the class-and landscape-levels, and reported the aggregate cooling effect of clustered vegetation patches compared to dispersed and fragmented patterns [39]. Maimaitiyiming et al [40] analyzed the relationships between the UHI effects and green spaces configuration through TM thermal infrared imagery finding that increasing edge density of the green space can improve the urban thermal environment.…”