Impacts of Urban Expansion on the Loss and Fragmentation of Cropland in the Major Grain Production Areas of China

Zifeng Yuan,Dongqi Sun,Fengning Hu,Liang Zhou

doi:10.3390/land11010130

Abstract

The continuous expansion of urban land has led to massive encroachment upon cropland. To examine the impacts of urban expansion on the loss and fragmentation of cropland in China’s nine major grain production areas (MGPAs), we used standard deviation ellipse, land use transfer matrix, land use dynamic degree, and landscape metric to explore the spatio-temporal evolutions, mutual transfer, and landscape patterns of cropland and urban land. The results show the following: (1) From 1995 to 2018, the areas of cropland in MGPAs showed a trend of “short-term increase—long-term decrease—short-term increase”, while that of urban land grew continuously; (2) Urban expansion is the main cause of cropland loss. The cropland area converted to urban land accounts for a large proportion (49.26%) of the total transfer of cropland to other land types, especially in the densely populated, rapidly urbanizing and industrializing Taihu Lake Plain, Jianghuai Region, and Pearl River Delta; (3) In most MGPAs, urban expansion has led to fragmentation of cropland, especially in the Pearl River Delta, as indicated by the significant change of patch density. However, in the Sanjiang Plain and Songnen Plain, a less pronounced or even reduced cropland fragmentation was observed due to the significant conversion of other land types to cropland under specific land policies. From these results, we suggest that the government should regulate the encroachment of urban land on cropland and the transfer of natural land to it, and encourage the rural land consolidation to increase the cropland.

Highlights

The world has experienced dramatic urbanization in recent decades [1]
The scale of the analysis focuses on countries, provinces, and regions, whilst few studies have considered this issue from the perspective of China’s major grain production areas (MGPAs, called commodity grain bases in Chinese) [31,32], Land 2022, 11, 130 these areas are the core areas of China’s grain production and the key to ensuring its food security
We explored the evolution of cropland and urban land, occupation of cropland by urban land and impacts of urban land on the fragmentation of cropland, with the intent of understanding the spatiotemporal evolution, effects, and ongoing exchange between cropland and urbanization; providing a reference base to guide the rational formulation of cropland protection and regional development policies

Summary

Introduction

The world has experienced dramatic urbanization in recent decades [1]. According to statistics, the global urbanization rate was 50% in 2009 and is expected to rise to 68% by 2050, and the urban population will grow by more than 2/3, with about 90% occurring in the urban centers of Asia and Africa [2]. The urban population of developing countries is expected to double and the build-up area to triple between 2000 and. As the most dramatic form of land use/land cover change, is a visual manifestation of urbanization [4]. While urban expansion creates a built environment for house urban populations and their activities [5], it has a negative impact on habitat quality [6], ecosystem services [7], regional climate [8], biodiversity [9], and hydrology [10]. Most of the relevant studies focus on exploring the drivers of urban expansion, analyzing the impacts of urban expansion on regional ecology and environmental, and digging the coupling relationship between urban expansion and socio-economic development [11]

Methods

Results

Discussion

Conclusion