Influence of road network expansion on the landscape ecological risk in the Yangtze River Delta region over the past two decades

Abstract

One of China's regions with the finest foundations for urbanization, the Yangtze River Delta (YRD), has experienced tremendous urbanization growth over the past 20 years. It is crucial to assess how the region's rapidly expanding road network may affect the landscape ecological risk (LER) by using landscape analysis, kernel density estimation and statistical analysis. The findings concluded that 1) The LER, which was significantly affected by the landscape pattern and topography was unevenly distributed throughout the YRD region, exhibiting obvious characteristics of high LER values in the north and low LER values in the south. From 2005 to 2020, the medium and sublow LER zones showed increasing trends, with increases of 7101 and 3186 km2, respectively. The decreased areas reached 5310, 2583, and 2394 km2 for the low, subhigh, and high LER zones, respectively. 2) There were obvious spatial differences in the impact of road networks on the LER’s geographical distribution in the YRD region. Significantly negative correlation areas were mainly distributed along and around the minimum spanning tree (MST) generated by the city centers of provinces, which had dense road networks. Significantly positive correlation areas were far away from the MST. 3) From 2005 to 2020, road network expansion in the YRD region impacted the interannual changes in both the LER index and each component index. As the road network expands, the fragmentation, splitting and disturbance indices of shrubs, grasslands and impervious land patches decrease, while those of croplands, forestlands, and water bodies increase. This study can serve as a scientific foundation and point of reference for planning the road network expansion and assessing the regional ecological risk in the YRD region.