Understanding the effects of managed realignment schemes on salt marsh recovery by assessing the spatiotemporal patterns of vegetation colonization in the Bay of Fundy, Canada

Abstract

As a coastal region, Atlantic Canada is highly susceptible to the impacts imposed by climate change. As hazards such as sea level rise, storm surge, and shoreline erosion are becoming more widely recognized, there is an increased need for communities to adapt to climate change to reduce their vulnerability. Nature-based solutions (NbS) have presented themselves as a more viable long-term solution to their hard engineering counterparts. Managed dyke realignment (MR), a form of NbS, is being used to restore critical salt marsh habitat which offers several ecological, economic, and social benefits through the provision of ecosystem services. This study aimed to determine the effects of MR schemes on estuarine morphodynamics and restoration trajectories by assessing the spatial and temporal patterns of vegetation colonization of a managed realignment site in the Bay of Fundy. The evolution of habitat community structure; the spatiotemporal patterns of vegetation colonization; and the relationship between vegetation colonization and topographic features were analyzed using remote sensing and GIS techniques. Results demonstrate that the restoration trajectory is a highly successional process with initial dominance of vegetation colonization via seed and a shift toward clonal spread later in the trajectory. There was a stronger relationship between vegetation colonization and channel networks in Year 1 post-restoration than consecutive years and S. <i>alterniflora</i> and early colonizers coincided with higher accretion rates than other classes. These results provide insight regarding the trajectory of restored sites and key factors to facilitate successful MR design.