Divergent plant and microbial community change in response to coastal salinization and sea level rise

Diverging community responses of plants and microbes to global change have the potential to disrupt ecosystem function and resiliency. Saltwater intrusion and sea level rise (SWISLR) threaten coastal ecosystems and are associated with multiple stressors—salinization, alkalinization, and inundation. However, how plant and microbial communities respond in tandem to these environmental changes remains uncharacterized. We sought to determine which SWISLR stressor(s)—salinity, pH, or elevation (inundation risk)—best predict plant and microbial community turnover (change in species composition) and richness and to investigate whether community shifts are correlated or divergent in coastal wetlands. We sampled three transects within the Albemarle-Pamlico Peninsula, North Carolina, USA, reflecting gradients of SWISLR. Along the transects, we characterized vegetation and sampled soils for microbial and chemical composition. We found that pH was an equally, if not more, important predictor of community turnover and richness than salinity, but that plant and microbial communities had distinct changes associated with SWISLR stressors. We identified more microbial indicator taxa associated with changes in pH than either salinity or elevation, and community turnover of plant and microbial communities across salinity gradients was parallel, but diverged across pH. Soil alkalinization associated with SWISLR may be a more powerful and accurate predictor of plant and microbial community change than variation in soil salinity in acidic coastal wetland soils. The distinct plant and microbial community changes we observe across gradients point to potential mismatches in how plant and microbial communities adapt to SWISLR, underscoring the need to assess their responses collectively for a complete understanding of SWISLR impacts on coastal ecosystems.

Duke Scholars

Author Justin Prouty Wright Biology