Discussion

Following the first simulated storm surge, rather minimal impacts of saltwater were seen. In retrospect, it is not surprising due to the slow diffusion of salt into a wet soil. Much of the impact was seen following the surge. Although the saltwater was being diluted (see Figure 4), it was still slowly diffusing into the soil and affecting photosynthesis and water relations.

As a consequence of these results, the plants were overwintered to allow for a second simulated storm surge. The response of the FLOODED plants, which received a surge in 1994 similar in characteristics to the 1993 surge, was similar to the SURGE plants in 1993. Plants for which the floodwater was allowed to drain off for two weeks before the second simulated storm surge were much more impacted by the saltwater. Saltwater infiltrated into the rhizosphere and directly affected the plants, both during and following the saltwater addition (Figure 5). This was seen visually in the foliage turning red and in the photosynthesis and water relations data. Chloride concentrations of the foliage (Figure 6) also show the impact of the saltwater.

The apparent contradictory relationship between chloride concentration and age in the two treatments illustrates the complexity of plant response in which the concentration may be toxic at high concentrations but at lower levels may only indirectly affect the plant through altered water uptake, which subsequently affect leaf water potentials. As the most severely impacted plants immediately lost their foliage, the soil-plant-atmosphere water continuum was slowed, which may have been responsible for the plant survival in the next spring albeit with little foliage.