Abstract Community responses to restoration are notoriously difficult to predict, and intensifying global pressures (e.g. sea level rise, species range shifts) amplify this challenge. Subtropical communities, which are already responding rapidly to multiple stressors, provide an ideal context for exploring restoration responses under evolving ecological conditions. To investigate how restorative sediment amendments that address sea level rise vulnerability influence alternative plant communities in the subtropics, we manipulated sediment thickness (+0 cm, +15 cm or +30 cm) and sediment composition (1%‐silt or 10%‐silt) in plots initially dominated by smooth cordgrass ( Spartina alterniflora ) or black mangroves ( Avicennia germinans ) in a 26‐month field experiment on Florida's north‐eastern coast. We show that sediment thickness shapes ecological recovery timelines with both plant biomass and invertebrate abundance recovering faster from +15 cm than +30 cm additions, but saw little effect of sediment composition on outcomes within the 26‐month period. Cordgrass and mangroves were not equally tolerant of burial: cordgrass biomass in sediment addition plots recovered to or doubled control‐level biomass by the end of the study while mangrove biomass remained less than half that of reference levels post‐burial. Resultantly, initial mangrove dominance was minimized or reversed by sediment addition. However, establishment of new mangrove propagules was four to six times higher in sediment addition plots than controls, suggesting that elevational increases could nullify initial mangrove biomass loss by facilitating the longer term conversion to mangrove forest. Mobile invertebrates, especially burrowing crabs, recovered from burial by the end of the study, but sessile ribbed mussels failed to re‐establish in sediment addition plots. Sediment addition alleviated salinity stress but had little effect on sulphide concentration between treatments. While plants and invertebrates returned, soil properties in sediment addition plots differed starkly from controls at the final time point, indicating that these remain altered well beyond 26 months but do not necessarily limit community recovery. Synthesis and applications . Our results reveal that emerging ecological communities may tolerate and benefit from restoration similar to better studied temperate systems. However, we show that community composition in these habitats may shift and develop along different trajectories in response to restoration interventions, with implications for managers targeting specific post‐restoration outcomes. Read the free Plain Language Summary for this article on the Journal blog .
Hay et al. (Sun,) studied this question.