Spatiotemporal evolution differences of urban green space: A comparative case study of Shanghai and Xuchang in China

Abstract

Urban green spaces (UGS) are vital for developing and evolving natural elements in urban spaces. The UGS information of a megacity behemoth (Shanghai) from 1996, 2006, and 2016, and a small and medium-sized city (Xuchang) from 2010, 2015, and 2019 was used as the basic data. The UGS evolution spatiotemporal characteristics were analyzed using the area change index, spatial morphological dimension, and spatial aggregation dimension. The changes of greening policies for UGS evolution in the two cities were compared. The results indicated that: (1) the UGS in downtown Shanghai mainly developed southwards from 1996 to 2006, then northeastwards and northwestwards. The UGS in downtown Xuchang mainly developed northeastwards and northwards between 2010 and 2019; (2) the spatial morphological dimensions of UGS in downtown Shanghai gradually increased indicating the UGS had systematic coordination and stability. The spatial morphological dimensions of UGS in downtown Xuchang first increased then decreased, indicating that the UGS tended to be integrated and systematic; (3) the spatial aggregation dimensions of UGS in downtown Shanghai decreased first and then increased, and the focus of UGS construction shifted from the center to the suburbs. The spatial aggregation dimensions of UGS in downtown Xuchang gradually increased, and the spatial distribution of UGS tended to be multi-center clustered; and, (4) under the guidance of greening policies, UGS evolution in Shanghai was progressive with stronger self-organization ability, while that in Xuchang leaped forward with weaker self-organization ability. The research results can provide a reference for other similar sized cities in UGS planning and government decision-making.