Sea-level rise can reverse the conditions that promote the spread of ecosystem engineers

Climate change and its consequences such as sea-level rise will modify environmental gradients, altering the spatial spread and persistence of plant populations. However, ecosystem engineers can also modify environmental gradients. To quantify the potential interactive effects of climate change and ecosystem engineering on population spread rates, we develop a spatial model that explicitly focuses on feedbacks between coastal vegetation growth and the environmental gradient of marsh elevation. We use the model to determine how sea-level rise could change how ecosystem engineering affects the spread rate of marsh populations. The model demonstrates that low levels of ecosystem engineering can produce the highest population spread rates in the absence of sea-level rise in initially low-elevation marshes. However, higher rates of ecosystem engineering and initially higher elevation marshes produce the highest population spread rates in the presence of sea-level rise. Sea-level rise can therefore reverse the conditions that drive high rates of spatial spread: engineers with low rates of spatial spread prior to sea-level rise may spread faster as sea levels rise. This result suggests that sea-level rise may promote the spread of invasive ecosystem engineers that previously experienced low rates of spatial spread. Moreover, ecosystem engineering can serve as a mechanism for adaptation to climate-driven changes in environmental gradients. Ecosystem engineering has the potential to rescue both native and exotic plant populations from climate-driven decreases in habitat suitability.