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Manifestations of climate change in the forms of sea level rise, extreme weather events, and rising temperatures elicit short- and long-term changes in coastal wetlands by altering the physical conditions that affect the survival of wetland vegetation. Previous research has focused on the relationship between coastal vegetation dynamics and climate change phenomena in dominant wetland ecosystems such as saltmarsh and mangrove forest; however, little work has been conducted in wetlands with limited distributions. This study investigates long-term vegetation trends in forested freshwater islands concentrated along the Big Bend coast of Florida (USA). In 2014 we conducted a tree census and understory sampling in 13 previously established forest plots located along a tidal creek in Waccasassa Bay Preserve State Park, extending a dataset that started over twenty years ago. Ten plots occur in forest islands surrounded by saltmarsh and three occur in continuous forest. Earlier studies found that salt stress from increased tidal flooding frequency prevented tree regeneration in frequently flooded plots, resulting in relict forest stands. By 2014, four of the six island plots subject to 10 or more weeks of tidal flooding had no live trees and two plots had one live tree each. Tree survival declined in all other island plots while survival remained stable in the continuous forest plots. Results of understory sampling show a successional trajectory in which dominant vegetation transitions from forest to saltmarsh shrubs to herbaceous saltmarsh along a tidal flooding gradient. These vegetation trends indicate that forested islands, a characteristic feature of the Big Bend landscape, are headed toward extinction. Ongoing research includes understanding landscape-level spatial patterns of forest island decline, examining the potential for mangrove encroachment in relict stands, and testing the extent to which different trajectories of climate change drive community reassembly in coastal wetlands. |