Survival and Growth of Seedlings of Four Bottomland Oak Species in Response to Increases in Flooding and Salinity

Abstract
Four oak species representing a range of flood tolerance were chronically (simulating sea level rise) and acutely (simulating hurricane storm surge) exposed to increased flooding and salinity in a complete factorial experiment. Survival, growth, and final biomass were measured to assess differential species' responses. No Nuttall or overcup oak seedlings died when flooded with fresh water, but 10% of the swamp chestnut and 35% of the water oaks died. Floodwater salinities of 2 and 6 g L-1 resulted in mortality of all seedlings of all four species. Watering with 2 g L-1 saline water did not cause any mortality although leaf browning was evident in all species. Overcup oak seedlings were the most tolerant to watering with 6 g L-1 saline water (100% survival), while the other three species had high mortality. Increased salinity, both in watered and flooded conditions, generally resulted in decreased diameter growth and decreased root and shoot biomass. Short-term increases in salinity (simulated storm surge) resulted in total mortality of flooded seedlings, while drained seedlings recovered and leafed out the following spring. Results indicate that these bottomland oak species would be seriously affected by increased flooding and salinity from either hurricane storm surges or sea level rise. For. Sci. 44(4):618-624.