COS 272-2 - Effects of hydrologic changes on vegetation and soil characteristics along marl prairie-Slough gradients in Everglades, Florida

Abstract: Background/Question/Methods



In the Everglades, where plant communities are primarily arranged along hydrologic gradients, both vegetation composition and soil characteristics respond to spatio-temporal changes in hydrologic regimes. Within Everglades National Park (ENP), the long hydroperiod, peat-dominated ridge-slough landscape in Shark River Slough (SRS) is flanked by short-hydroperiod marl-dominated prairies, the habitat of Cape Sable seaside sparrow (CSSS), a federally-listed endangered species. During the 20^th century, both vegetation composition and soil characteristics along the gradients were adversely impacted by management-induced hydrologic changes. However, since early 2000s, several hydrologic restoration activities under Comprehensive Everglades Restoration Plan (CERP) and associated projects have been undertaken to mitigate the damage to Everglades’ ecosystems caused by past management. With a goal of understanding the response of landscape-level processes to hydrological restoration, we studied spatio-temporal variation in vegetation structure and composition and soil characteristics along the marl prairie-slough gradients for 17 years (2005-2022). Along the gradients, vegetation was sampled five times during that period, while soil characteristics were determined at a sub-set of sites only in 2016.



Results/Conclusions



Our results show that vegetation change patterns along the marl prairie-slough gradients varied spatially, primarily responding to changes hydrologic condition. In the peat-dominated ridge and slough portion of the gradient, relatively dry conditions in the early 2000s caused an increase in abundance of species that are indicative relatively dry conditions and at the expense of open water sloughs. However, a reverse trend of vegetation change has been observed in most recent decade. Vegetation at the marl prairie sites located west of the SRS showed a drying trend partly due to regulated water deliveries through the S12 structures implemented in 2002. In contrast, east of the SRS, vegetation was indicative of slightly wetter conditions in recent years. The vegetation shift was resulted from a broader restoration strategy, including the rehydration of the Rocky Glades and increased water deliveries through Northeast Shark River Slough (NESRS). Since the deterioration of eastern marl prairies was considered to have resulted from over-drainage followed by frequent fire, only time will tell whether the recent vegetation shift towards a more mesic type will result in an improvement in CSSS habitat conditions. Our study has implications for marl prairie and ridge and slough management in the southern Everglades and will also provide feedbacks to the resource managers for evaluating the restoration success in the Everglades.