Spatial and temporal variations of quantity and quality in greenspace in Seoul over 1987-2017

Abstract:

Urbanization is a major driver in reducing greenspace for citizens and habitats for wildlife. Previous studies have focused on the changes in the amount of urban greenspace at various scales, but little consideration was given to monitoring and interpreting both quantity and quality of urban green space over the long-term period. Here, we examined the spatial and temporal variations of greenspace in Seoul, Korea, using a 30-year time series (1987 – 2017) of Landsat satellite imageries in Google Earth Engine. Continuous Change Detection and Classification (CCDC) and a random forest algorithm were integrated to classify urban land cover types. We mapped the normalized difference vegetation index (NDVI) in Seoul and found overall greening trend at the city scale (34%, from 0.36 to 0.49). Greening trend was mainly attributed to expanding green space in street trees and parks rather than growth of natural vegetation. Over the three decades, total area of green space in 114 km² has been made while 31 km² of green space has disappeared. These findings will be useful in urban greenspace management and policy decisions.