Conflict or Coordination? measuring the relationships between urbanization and vegetation cover in China

Abstract

Understanding the relationship between urbanization and vegetation is essential for sustainable urban development. Over the last few decades, China has experienced rapid and dramatic urbanization along with impressive land transformations. However, the dynamic relationship between urban expansion and vegetation cover lacks enough understanding. We proposed an urbanization-vegetation cover coordination index (UVCI) by combining the physical boundaries of cities at 10-year intervals and the 250 m vegetation index, and measured the conflict or coordination relationships between urbanization and vegetation cover for 338 cities in China from 1990 to 2018. The results show that China has experienced a process of rapid, large-scale, but uneven urban expansion over the past 30 years, with urban areas expanding by approximately 556 %. Urbanization has made China’s urban areas less green, yet vegetation cover changes vary between newly developed and older urban areas. There is a substantial tendency for vegetation degradation in the newly urbanized areas, whereas vegetation cover has generally improved in the older urban areas. The vegetation in non-urban areas has been showing a noticeable greening trend after 2010, with NDVI maintaining an annual growth rate of 0.89 %. The relationship between urbanization and urban vegetation cover in China is becoming increasingly coordinated. The proportion of conflict cities decreased from 93 % in 1990–2000 to 15 % in 2010–2018. The spatial heterogeneity of the UVCI is apparent, with northern Chinese cities having achieved a largely coordinated urban-vegetation relationship, while most southern cities still face challenges. The methodology of this study can be used as a reference for subsequent research, and the findings can help shape government policies that will support green and sustainable urban development in China.