Spatiotemporal Patterns and Driving Force of Urbanization and Its Impact on Urban Ecology

Meng Zhang,Di’En Zhu,Guomo Zhou,Fangjie Mao,Lv Zhou,Zihao Huang,Huaqiang Du,Xuejian Li,Yanxin Xu

doi:10.3390/rs14051160

Meng Zhang, Di’En Zhu + Show 7 more

Open Access

https://doi.org/10.3390/rs14051160

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Abstract

Urbanization inevitably poses a threat to urban ecology by altering its external structure and internal attributes. Nighttime light (NTL) has become increasingly extensive and practical, offering a special perspective on the world in revealing urbanization. In this study, we applied the Normalized Impervious Surface Index (NISI) constructed by NTL and MODIS NDVI to examine the urbanization process in the Yangtze River Delta (YRD). Geographical detectors combined with factors involving human and natural influences were utilized to investigate the drive mechanism. Urban ecology stress was evaluated based on changes in urban morphological patterns and fractional vegetation cover (FVC). The results showed that the NISI can largely overcome the obstacle of directly coupling NTL data in performing urbanization and has efficient applicability in the long-term pixel scale. Built-up areas in the YRD increased by 2.83 times during the past two decades, from 2053.5 to 7872.5 km2. Urbanization intensity has saturated the city center and is spilling over into the suburbs, which show a “cold to hot” spatial clustering distribution. Economic factors are the primary forces driving urbanization, and road network density is becoming essential as factor that reflects urban infrastructure. Urban geometry pattern changes in fractal dimension (FD) and compactness revealed the ecological stress from changing urban external structure, and internal ecological stress was clear from the negative effect on 63.4% FVC. This impact gradually increased in urban expanded area and synchronously decreased when urbanization saturated the core area. An analysis of ecological stress caused by urbanization from changing physical structure and social attributes can provide evidence for urban management and coordinated development.

Highlights

Nighttime light (NTL) data combined with MODIS NDVI can improve the data continuity and reliability of long-term urban monitoring, which provides a new reference for time series urban monitoring
Urbanization dynamics in the Yangtze River Delta (YRD) show that, accompanied by reaching saturation in the city center, urban-development gravity gradually moves to the periphery
In the process of physical structural changes caused by urban expansion, changes in fractal dimension (FD) and compactness can eventually complicate the urban landscape structure and increase urban ecological stress

Summary

Introduction

China’s rapid urbanization has driven unprecedented changes in land use and landcover change (LUCC) over the past few decades [1], accompanied by shifts in urban scale, urban environment, urban energy, and various urban socioeconomic indicators [2]; while the external spatial structure, i.e., physical attributes, is changing, the internal economic characteristics with social attributes are changing [3,4]. Obtaining accurate and timely information about the dynamics of urban development is crucial to clarify the driving forces of urbanization [5,6]. Previous studies have demonstrated that remote-sensing data have advanced capabilities in urban extent delineation and urban impervious-surface mapping, 4.0/). Due to increasing urban complexity, the ability to analyze the spatial structure of large-scale urban systems and estimate urban socioeconomic characteristics needs to be improved [10]

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Discussion

Conclusion