Effects of salinity on seed bank germination in a freshwater/brackish tidal marsh

Sea level rise, as a consequence of global climate change, is expected to elevate\ud salinities past tolerable ranges of many of the species occurring in\ud freshwater/brackish tidal marshes. In this study, I collected soil seed banks along a\ud freshwater to brackish gradient on Browns Island at the junction of the Sacramento\ud and San Joaquin Rivers. I tested whether the seed banks from the freshwater end of\ud the gradient were more inhibited by salinity than those from the brackish end. I used\ud multiple salinity treatments and monitored their effects on seed bank germination\ud rates. Seed banks were strongly impacted by salinity even at the lowest treatment\ud concentration. The seed banks along the gradient, however, were not differentially\ud affected, suggesting that the seed banks on the island were more similar than\ud expected. Similarity analyses indicated that the seed banks did not correlate with\ud local standing vegetation; an indication that inter- and intra-wetland dispersal is a\ud stronger process than simple local dispersal. Germination rates as a whole declined\ud as salinity levels were increased; freshwater species were far more inhibited by\ud salinity than their brackish counterparts. Halophytes were the only species not\ud inhibited to the degree the freshwater and brackish species were