SURVIVAL AND GROWTH OF SEEDLINGS OF 4 BOTTOMLAND OAK SPECIES IN RESPONSE TO INCREASES IN FLOODING AND SALINITY

Four oak species representing a range of flood tolerance were chronica lly (simulating sea level rise) and acutely (simulating hurricane stor m surge) exposed to increased flooding and salinity in a complete fact orial experiment, Survival, growth, and final biomass were measured to assess differential species' responses. No Nuttall or overcup oak see dlings died when flooded with fresh water, but 10% of the swamp chestn ut 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. Wateri ng 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 m ost tolerant to watering with 6 g L-1 saline water (100% survival), wh ile the other three species had high mortality, Increased salinity, bo th in watered and flooded conditions, generally resulted in decreased diameter growth and decreased root and shoot biomass, Short-term incre ases in salinity (simulated storm surge) resulted in total mortality o f flooded seedlings, while drained seedlings recovered and leafed out the following spring. Results indicate that these bottomland oak speci es would be seriously affected by increased flooding and salinity from either hurricane storm surges or sea level rise.