Extreme weather events pose large impacts on urban trees: Freezing rain events as an example

Abstract

Global warming increases the frequency of extreme weather events, resulting in greater risks to urban ecosystems. Among such events, freezing rain events have received little attention despite their significant impact on urban trees. Previous research lacked the spatiotemporal resolution to separate event-driven damage from seasonal variation and to capture fine-scale urban landscape variation. This study developed an integrated framework combining multi-index remote sensing and machine learning to assess the impacts of the February 2024 freezing rain events in Wuhan. The results revealed that freezing rain events led to a 49.88 % decline in the composite vegetation index (CVI) and affected 95.10 % of tree-covered areas. Aboveground biomass (AGB) loss reached 0.09 Mg/ha, equivalent to 1.43 times the normal seasonal variation. Greater tree damage occurred in regions with denser tree cover. In addition, broad-leaved evergreens experienced more pronounced damage relative to evergreen conifers and deciduous species. These findings underscore the need for targeted management strategies, including species selection and zoning-based planning, to enhance urban forest resilience against future freezing rain events.