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Environmental Gradients and Overlapping Ranges of Dominant Coastal Wetland Plants in Weeks Bay, AL

Constantin, Adam J., Broussard, Whitney P., Cherry, Julia A.
Southeastern naturalist 2019 v.18 no.2 pp. 224-239
Cladium mariscus subsp. jamaicense, Juncus roemerianus, Spartina cynosuroides, altitude, coasts, dominant species, littoral zone, marshes, microrelief, plant communities, population distribution, salinity, sea level, surveys, swamps, wetland plants, Gulf of Mexico
Predicted changes in sea level and other environmental conditions may threaten the marginal occupancy of coastal wetlands. In a field survey conducted in Weeks Bay, AL, we investigated intertidal wetland plant zonation along environmental gradients. The results of this survey may have implications for coastal wetland resilience both locally and across the Northern Gulf of Mexico as changing environmental conditions exceed plant community tolerances, resulting in “coastal squeeze” phenomena. Within the coastal marsh transition of Weeks Bay, there was heterogeneous micro-topography with a large overlap of plant distributions along the elevation gradient (-0.474–0.661m NAVD 88). In addition to elevation, salinity was a primary indicator of plant zonation for the dominant species in the area: Spartina cynosuroides (Big Cordgrass), Juncus roemerianus (Black Needlerush), and Cladium mariscus ssp. jamaicense (Swamp Sawgrass). Based on our findings, the persistence of these plants in the intertidal zone of Weeks Bay may be especially susceptible to changes in flooding and salinity associated with sea-level rise and the presence of barriers to upslope migration.