Urbanization and landscape dynamics: Local and regional ecological and environmental impacts

Background/Question/Methods

Over the past several decades, China went through a very rapid and magnificent urbanization process. It is certain that this trend will continue. In the recently released National New-type Urbanization Plan, China sets the target to raise its urban population proportion by 1% each year, to reach 60% by 2020. That is, every year, there will be approximately 18 million people, the size of the total population in the Los Angeles Metropolitan area, added into established or new cities. This rapid and magnificent urbanization process in China has dramatically changed, and will continue to change the local, regional, and even global environments. Such changes greatly alter ecological functions and processes, with significant consequences for ecosystem services and human wellbeing. This paper presents the results of the comparisons of the extent, rate, and spatial pattern of urban expansion, and associated ecological effects from 1980 – 2010 across six rapidly urbanizing regions in China. These included Beijing-Tianjin-Tangshan, Yangzte River Delta, Pearl River Delta, Chengdu-Chongqing, Wuhan, and Changsha-Zhuzhou-Xiangtan, which together carry 30% of the total population in China, and generate approximately 50% of the gross domestic production (GDP).

Results/Conclusions

We found: 1) there were dramatic increases in developed land for all of the six regions. The proportion of developed land increased the most in the Yangzte River Delta, from 4.12% to 21.85%, or an increase of approximately 20000 Km². 2) the spatial distribution and temporal dynamics in urban expansion varied greatly among regions, as well as within each urban region, reflecting expedited urbanization in more recent years and the spatial shifting of development hotspots; and 3) urban expansion caused great loss of agricultural lands and increased fragmentation, reduction in biomass and net primary productivity (NPP) in urbanizing regions, serious air pollution and dramatic reduction in visibility in cities and surrounding regions, and intensified urban heat islands and the form of urban heat “archipelagos”. This study provides insights on the process of urban expansion, and its ecological consequences in China, and thus has important implications for urban growth planning and management.