Soil Salinity Impacts Future Community Composition of Coastal Forests

With projected increase in storms, sea-level rise and saltwater intrusion in low-lying terrestrial areas, compositional changes that favor more salt tolerant species are likely to occur. Wetland species are expanding into declining forested communities, primarily dominated by trees. Higher salinities for germination may preclude establishment of tree species. We examined the capacity for coastal tree species (Acer rubrum, Liquidambar styraciflua, Pinus taeda, Celtis occidentalis, Persea borbonia) and a wetland shrub (Morella cerifera) to germinate at salinity concentrations of 0, 2, 5, 10, and 20 ppt. A growth chamber experiment was established examining the effect of salinity on germination of common species found in mixed forests throughout the mid-Atlantic coastal plain and Gulf of Mexico, USA. The study revealed that regeneration from seed will be difficult for most of the selected species at salinities >5 ppt with implications for community composition with continued saltwater intrusion. Germination of A. rubrum was not impacted at higher salinities, with Pinus taeda not as affected other species. Morella cerifera did not have an advantage at the germination stage over selected tree species. Knowing threshold limits of germination response to salinity is critical for identifying future community trajectories.