Impacts of different levels of urban expansion on habitats at the regional scale and their critical distance thresholds

Abstract

With the rapid development of urbanization, natural habitats in many parts of the world have been seriously damaged by urban expansion. However, urban expansion is a complex process, and the impacts of different levels of urban expansion on habitats at regional scales and their distance thresholds are still unclear. We conducted a study in Hubei Province, China to evaluate the impacts of the expansion of prefecture-level cities and county towns on the quantity, area, and quality of natural habitats and the critical threshold distances affecting habitats. The results show that, at a regional scale, habitat degradation was driven primarily by the expansion of large numbers of county towns, but the expansion of prefecture-level cities affected habitat degradation over greater distances . Specifically, the impact of county town expansion on habitat first increased and then decreased with greater distance from built-up areas, the threshold distances for habitat quantity and quality being approximately 8 km and 80 km, respectively. The impact of expanding prefecture-level cities on habitat showed a similar nonlinear change with greater distance, but the distance thresholds for habitat quantity and quality rose to approximately 40 km and 130 km, respectively. These findings not only reverse the conventional view that the expansion of large cities dominates habitat degradation, but also draws more attention to the influence of the expansion of numerous small county and towns on habitat, when measured at the regional scale. Understanding the distance threshold of particular spatial impacts can be help to inform spatial decision-making with regards to habitat conservation.

Spatiotemporal Evolution and Mechanisms of Habitat Quality in Nature Reserve Land: A Case Study of 18 Nature Reserves in Hubei Province

“…Hydrology, water bodies, and landscape patterns also broadly affect habitat quality changes in various types of nature reserves. From the singlefactor detection results of the socio-cultural dimension, although the study's findings on the explanatory power of single factors in land use are consistent with the existing literature [28][29][30][31][39][40][41], this paper also makes further discoveries. Among subsequent influencing factors, the impact of open, lower-grade roads exceeds that of closed, highergrade roads, showing an annually increasing trend, which reminds us to pay more attention to the control intensity of development along roads.…”

“…For instance, Pengnan Xiao and others have evaluated the spatiotemporal characteristics of habitat quality across Hubei Province and the impact of topographic gradients on habitat quality [39]. Shuaipeng Chen has assessed the influence of the expansion of prefecture-level cities and counties on the quantity, area, and quality of natural habitats, as well as the critical threshold distances affecting habitats [40]. Moreover, Meng-yao Li and others have evaluated the effects of topographic gradient on habitat quality in northwestern Hubei, using the city of Shiyan as a case study, by employing the topographic position index [41].…”