Wetland forests have been an influential component of the economy and culture of the southeastern US since the earliest settlements. These ecosystems have been used for transportation, food and fiber, flood control, wildlife habitat, and recreation. The importance of these areas to society has been recognized more in recent years, and there has been a surge in research on conservation and restoration of wetland forests. Because tidal wetland forests, located at the interface of watersheds and estuaries, have considerable carbon storage potential, these tidal freshwater ecosystems provide a very important ecosystem service we need to protect and restore. However, wetland forests along the coast are currently converting from freshwater forested wetland to salt marsh. Even small concentrations of salinity (e.g., <2 ppt) drastically decrease growth rates and litterfall production, leading to decreased productivity and permanent changes in the composition of these forests. We have documented changes in forest structure and growth of trees in swamps of South Carolina, Georgia, and Louisiana from 2004 to 2017 subject to a variety of flooding regimes. Water levels were continuously monitored, litterfall was measured monthly, and tree growth was monitored annually.
Results/Conclusions
In this synthesis, we review past experiences in wetland forest regeneration efforts, identify current issues that restrict regeneration, and provide recommendations for improving coastal wetland resilience. One limitation to restoring coastal forested wetlands is that efforts are mostly small-scale with varying funding sources over a 25-year time frame. Overcoming difficulties associated with propagating good trees, planting seedlings on a large scale in a trying environment, and establishing robust monitoring programs will require a dedicated multi-institutional approach. Restoration efforts may be enhanced considerably if coupled with hydrological restoration. Large-scale restoration of coastal forests should be attempted to create a landscape capable of minimizing storm impacts. Because hydrological alterations in many forested wetland sites has increased flooding, planting is a preferred regeneration method. Once planted, seedlings need to be protected from herbivory to enhance establishment. Finally, to restore ecosystems that are resilient to climate change, programs identifying salt tolerance in coastal forest tree species are critical for restoring areas that are vulnerable to saltwater intrusion.