Vegetation Dynamics and Their Response to the Urbanization of the Beijing–Tianjin–Hebei Region, China

Yuyang Chang,Geli Zhang,Jingxia Wang,Zhen Xie,Tianzhu Zhang

doi:10.3390/su12208550

Abstract

Rapid global urbanization has caused substantial changes in land cover and vegetation growth. Rapid urban growth in a short time has escalated the conflicts between economic development and ecological conservation, particularly in some metropolitan regions. However, the effects of rapid urbanization on vegetation have not been fully captured, especially accounting for the latest ecological development initiatives. In this study, we chose a typical urban agglomeration, the Beijing–Tianjin–Hebei (BTH) urban agglomeration in China, and analyzed the vegetation variation and the impacts of urbanization on the vegetation growth based on transferable methods, using data such as the Normalized Difference Vegetation Index (NDVI) and the nighttime light (NTL). The results indicate significantly enhanced vegetation growth in the BTH region, with a strikingly spatial pattern of greening in the northwest, and browning in the southeast from 2001 to 2018. Besides this, the results enclose most of the areas (72%) of built-up land in the BTH, which tended to brown in the process of rapid urban development, while 27% greened with increasing urbanization. This means that the vegetation’s response to urbanization shows apparent differences and geographic heterogeneity along the urbanization gradient at the urban agglomeration scale. Parts of the periphery of the metropolis and the central areas of developing cities may experience a browning trend; however, the core urban areas of urbanized metropolises demonstrate greening, rather than browning. Furthermore, this study provides solid evidence on the remarkable greening impacts of several ecological restoration projects which are currently underway, especially in ecologically fragile areas (e.g., the suburbs). The implications derived from the urban ecological development and the transferable methodology deployed in this paper facilitate the unfolding relationships between urbanization and social-ecological development. Our findings provide new insights into the interactions between vegetation dynamics and urbanization at the regional level.

Highlights

Urbanization is a common phenomenon in the process of global modernization, and it is an important indicator of social progress and economic development [1]
Urban development usually leads to dramatic land use alternation, and it is usually recognized as a process that can cause ecological pressures to terrestrial ecosystems [2,3] resulting in irreversible consequences [4,5,6], such as environmental pollution, the shortage of resources, a drastic reduction of wetlands, the loss of biodiversity, and the degradation of urban ecological quality [7,8,9]
Our results have proved that these ecological projects in the BTH region have achieved positive results, especially in the ‘Taihang Mountains and Water and Soil Conservation Reserve’ (TMWSCR), the west of ‘Three North Shelterbelts Program’ (TNSP), and the north of ‘Afforestion Program for Taihang Mountain’ (APTM)

Summary

Introduction

Urbanization is a common phenomenon in the process of global modernization, and it is an important indicator of social progress and economic development [1]. Scholars throughout the world have conducted many studies using DMSP/OLS data [6,15,16] These datasets are applied to built-up area dynamic extraction [15,17], the extraction of the impervious surface area, the construction of urban spatial characteristic light indexes [18], population density and the heat island effect [16,19,20], social and economic development status [21,22], power and energy consumption [23,24], and the impact of urbanization on the ecological environment [25,26,27]. NTL and NDVI were scarcely integrated to explore vegetation variability in the process of urbanization, and few have received sufficient attention from the academic world [37]

Objectives

Methods

Findings

Discussion

Conclusion