Efficacy of stress acclimation techniques in coastal wetland plants (Spartina alterniflora and S. patens): implications for restoration and nursery production

Abstract The implementation of coastal nature-based features, created wetlands, and wetland restoration has increased globally over recent years. Many of these projects have been successful in meeting their goals, however, when projects fail, it is often attributed to mortality of transplanted vegetation. Transplant mortality may be due to inappropriate timing, poor site selection, or abiotic stressors associated with transplant shock. Science-backed guidelines have been well established in many coastal regions regarding site specifications and species selection, but nursery practices for reducing transplant shock remain inconsistent. In this study, we tested a combination of four salinity acclimation treatments and two inundation acclimation treatments on nursery-grown Spartina alterniflora and S. patens plugs. We measured a suite of plant functional traits to determine tradeoffs in plant response with a focus on traits associated with plant marketability, indicators of stress acclimation, and desired traits for restoration goals. A subset of plants was transplanted to a restoration site for analysis of their survival in situ. Exposure to salinity and inundation resulted in traits associated with both marketability and restoration goals (e.g., increased stem height, reduced dead to live stem ratio, and increased biomass), as well as evidence of acclimation to field stressors. However, trait differences did not translate to differences in field performance as survival and expansion of transplanted individuals showed no difference between acclimation treatments. The future of coastal wetland creation and restoration will require plant material that is produced using a science-based approach to ensure plants are robust, long-lived, and marketable to achieve the needs to restoration and nursery practitioners alike.