A major challenge in ecosystem science is evaluating how legacies of disturbance interact to influence system sensitivity and/or resilience to novel rates of chronic climate and land use changes. Long-term ecological research offers rich opportunities for unravelling how trajectories in ecosystem structure and function interact with multiple drivers after major disturbances. The Florida Coastal Everglades Long Term Ecological Research (FCE LTER) program has identified disturbance as a primary driver of ecosystem dynamics. Effects of chronic disturbance in the form of saltwater intrusion driven by sea level rise and reduced freshwater deliveries are modified by extreme episodic events including cold snaps, fires and, particularly, hurricanes. Three hurricanes (Katrina, Wilma, Irma) traversed the FCE over the last 18 years of record, providing an opportunity to test how storms influence the distribution and fate of carbon, trophic pathways, and ecosystem resilience to saltwater intrusion.
Results/Conclusions
Results show how historical exposure to frequent high-energy storms have conferred a high inherent degree of resistance of foundation plant species and mobile consumers to even major hurricane winds and associated storm surges. Rapid post-storm recovery of ecosystem functions is enhanced by phosphorus-rich storm surge mineral deposits that promote refoliation and regeneration in canopy gaps and prolonged connections to upstream habitats that provide high quality food resources for consumers. Models suggest healthy mangrove forests attenuate storm surge energy and trap deposits that can maintain elevation relative to sea level rise. However, massive export of dissolved organic carbon were documented after the most recent storm in 2017. Determining whether this lost carbon is sourced from upstream peat soils collapsing in response to saltwater intrusion is a subject of ongoing studies. If so, net positive feedbacks of storm disturbance that build resilience to sea level rise may be shifting toward net losses driven by increased saltwater intrusion. These results underscore the importance of freshwater flow restoration to the Everglades to not only counteract carbon losses driven by saltwater intrusion but to also retain carbon and elevation gains associated with high-energy storms. We interpret these results in the context of other disturbance-prone ecosystems confronted by multiple interacting drivers and legacies.