Assessing the impact of sea level rise on landscape connectivity of forests and wetlands in coastal Southeast USA

Abstract

Rising sea levels are causing lasting alterations to low-lying coastal landscapes, with the southeastern United States being particularly susceptible. The inundation of low-lying land by rising sea levels disrupts terrestrial linkages and intensifies erosion, leading to significant habitat fragmentation. Consequently, the movement patterns of wildlife and overall ecosystem functionality are negatively impacted. Understanding changes in landscape connectivity for forest and wetland ecosystems is crucial for assessing ecological impacts and guiding effective conservation efforts. This study aims to create an analytical methodological approach that assesses the impacts of sea level rise (SLR) on omni-directional landscape connectivity, while simultaneously exploring the factors that may drive these changes. This analysis, which includes the influence of core area (key habitat for recolonization/restoration) size and perimeter, is designed to serve as a direct reference for regional decision-makers. This study assessed landscape connectivity changes in two southeastern U.S. coastal counties (Chatham and St. Johns) using omnidirectional circuit theory under sea level rise scenarios through 2100. Ecological connectivity was modeled based on how different land cover types impede or facilitate movement. The resulting connectivity maps were then analyzed to identify changes and find correlations with core area metrics. Sea level rise will greatly affect forests and wetlands connectivity in Chatham and St. Johns counties. Current connectivity patterns are not uniform across the study areas. In Chatham County, inland areas have higher ecological flow than its more vulnerable coastal regions. Projections indicate that Chatham County faces a more severe overall decline in connectivity (17% to 50%) compared to St. Johns County (14% to 19%). The sample analysis reveals a clear relationship between core area size and vulnerability to connectivity decline, identifying priority protection zones that are disproportionately threatened by even minor sea level rise. The omnidirectional method effectively illustrated changes in cumulative and normalized current flow in Chatham County and St. Johns County with changes expected from sea level rise scenarios. We quantified significant shifts in connectivity patterns for each county. These findings have direct applications in urban planning and ecological analysis, strengthening coastal resilience and guiding future decisions on landscape connectivity.