Effect analysis of road structure on multidimensional fragmentation of cultivated land: A case study in the international metropolis of Shanghai City

Cultivated land fragmentation (CLF) is an important factor restricting agricultural scale production and modernization development. Recent studies have revealed that CLF is a multidimensional problem. A systematic study of the spatial distribution and driving factors of multidimensional cultivated land fragmentation (MCLF) has practical meaning for preserving high-quality farmland in suburbs and restraining urban land expansion. Taking the suburbs of the international metropolis of Shanghai City as an example, this article used canonical correlation analysis to calculate the effects of road structure on the MCLF in urban fringe, rural fringe and rural areas. The results showed that there was spatial heterogeneity in the degree of MCLF in the Shanghai suburbs in 2015. The size and distribution characteristics of CLF mainly occurred near the center of the main city, while the shape characteristics of CLF mainly occurred on the southeast coast. In addition, there was no positive correlation between road density and the degree of MCLF. Without the highest road density, the rural fringe had the highest level of distribution characteristics of CLF. Furthermore, the MCLF was affected by the road structure in heterogeneous zones. The higher density of the fourth-class road density represented a lower degree of the size characteristics of CLF in the urban fringe, and a higher density of the third-class road represented a higher degree of the distribution characteristics of CLF in the rural fringe. In rural areas, the area with a lower density of higher roads and a higher density of lower roads showed a lower CLF in terms of size characteristics and a higher CLF in terms of shape characteristics, while the area with a higher density of higher roads and a lower density of lower roads showed a higher CLF in terms of distribution characteristics. These discoveries enlightened us that to relieve the stress of cultivated land protection and achieve the goal of sustainable land use, we need to be explicit about the main challenges of regional cultivated land protection and consider the potential risks of road construction to the MCLF in the process of road planning and design.