Sea level rise is projected to increase over the upcoming decades, threatening coastal ecosystems worldwide. In systems where accretion does not keep pace with sea level rise, plant species may cope with environmental changes over the short term, but eventually they will be eliminated unless inland migration occurs. If coastal species are to maintain viable populations in the landscape, they must successfully colonize environmentally suitable areas in advance of deteriorating conditions. This requisite has implications for coastal restoration and conservation. Efforts to restore degraded coastal communities must take into account potential spatial shifts in habitat suitability considering the rate at which these shifts occur. Identifying areas available for colonization of downslope species can be problematic as the landward ends of many coastal transitions have been dramatically modified by humans through alteration of natural disturbance regimes, clearing, conversion to agriculture and urbanization. Long-term sustainability of coastal ecosystems will require landscape connectivity and dispersal corridors that allow for successful migration of species as their habitat envelopes shift inland. When suitable habitat is lacking, restoration of degraded inland habitat and/or assisted migration may be necessary. We develop a framework that can be used as a tool for conceptualizing the future requirements and restoration needs of coastal wetlands in different landscape and geomorphic settings.
Results/Conclusions For a given site, the rate of relative sea level rise is a critical component to estimating the duration and movement of habitat envelopes. A temporal series of habitat envelopes would inform restoration plans on appropriate time intervals and habitat boundaries in which to place targets. Landscape configuration, particularly on the upslope ends of transitions, is critical for determining whether there are foreseen impediments to dispersal and successful migration. If the transition is fragmented, but suitable upslope habitat exists, then assisted migration may be prescribed. Where upslope habitat is badly degraded, some physical restoration measures may be required before propagule introductions. Our framework can be used to develop a coarse schedule for occupancy of coastal species in current and future coastal transitions. Developing spatially and temporally appropriate restoration targets for coastal communities exposed to chronic sea level rise is challenging but necessary if resources are to be used effectively. Innovative land use policies, such as easements that roll inland with sea level rise, will be one feasible way to conserve and maintain local coastal transitions and migration corridors.
