Long-term assessment of ecological risk dynamics in Wuhan, China: Multi-perspective spatiotemporal variation analysis

Ecological Risk Assessment (ERA) is a critical component of ecosystem management aimed at identifying potential harms caused by human activities. However, previous studies have been limited by short periods, narrow perspectives, and a focus on single-risk factors, making it difficult to comprehensively assess ecological risk. To address these issues, our study investigates ecological risk changes in Wuhan from 1996 to 2020, adopting a multi-perspective method. We then employed a unified scalar overlay approach that fuses the Landscape Ecological Risk Index (LERI) and Habitat Degradation Index (HDI) to conduct an in-depth analysis of comprehensive ecological risk. It considers the interrelationships between threat sources and receptors, as well as the morphological structure of patches, to extract spatial information of ecological risks. Our results reveal that: (1) Wuhan's cropland decreased by 1760.98km2 (-38.95%), mainly converting to construction land and woodland. Simultaneously, construction land expanded outwards from the city center (+895.72km2). At the landscape level, Wuhan's landscape patches are becoming progressively more fragmented. (2) Total Ecological Risk Index (SERI) retains the "Low-High-Low" pattern of both LERI and HDI from the inside out, with high ecological risks radiating from the central urban boundary towards the surrounding regions. The lower-risk areas of the SERI converted mainly to the low-risk areas, whereas the area of higher-risk experienced a larger increase (+1083.45km2), mainly from high-risk areas. Overall, the SERI of Wuhan tends to move towards the north and east. (3) Spatially, hot-spots of risk are predominantly concentrated in the north of Wuhan, while cold-spots are primarily located in the city center. Confidence degrees of both hot and cold spots decrease from their center to the external areas. Additionally, ecological risk showed significant spatial dependency in its distribution. Given the current global environmental crisis, ecological risk research is more important than ever, and our new ERA framework is developed to provide valuable insights for urban planners to mitigate ecological risk.