Increased storm frequency in coastal communities exposes vegetation to increased salt spray. This change in climate regime may be partially responsible for the decrease in maritime forest regeneration that has been observed on barrier islands at the Virginia Coast Reserve, LTER site. While mature trees experience reduced growth due to higher salinities, earlier life stages may be more vulnerable. Environmental stress impacts seed germination, posing challenges for susceptible species and future regeneration of these forests. The goal of this experiment was to experimentally investigate the effects of increasing salinity on seed germination of common maritime forest species: Pinus taeda, Liquidambar styracifula, Quercus rubra, Juniperus virginiana, Celtis occidentalis and Persea borbonia. We tested the hypothesis that an increase in soil salinity will decrease germination in all species, with a higher salinity threshold in Pinus taeda. Seeds were collected from maritime forests in Virginia and were cold stratified prior to the experiment. In a growth chamber experiment we exposed tree species to 5 different soil salinities (0, 2, 5, 10, and 20 g L-1). Germination was monitored for 40 days and total percent germination was calculated. ANOVA was used to determine the effect of salinity on germination.
Results/Conclusions
Results show that germination was greater at lower salinities (0, 2, 5 g L-1). Species responded with a delay in germination at higher salinity levels. Pinus taeda was the only species to germinate at the highest salinity of 20 g L-1. Liquidambar styracifula, C. occidentalis, and Q. rubra failed to germinate at the highest salinity indicating their salinity threshold for germination was reached. Quercus rubra, however, had low germination rates at all salinities. Further analysis revealed that <10% of seeds were viable, suggesting that factors other than salinity may be important for its regeneration. These results show that increased salinity from salt spray and storm overwash impacts the community composition in coastal forests. Many species are intolerant of high salinity levels with delays in the timing of germination. Loss of maritime forests could alter barrier island structure (e.g. elevation gradients, soil erosion) and function (e.g. maintenance of freshwater aquifers, buffer for the mainland during hurricanes).