From little things, big things grow: using applied nucleation to restore marine forests

Abstract

Global habitat degradation has prompted an urgent need for efficient restoration strategies at appropriate spatial scales. “Applied nucleation” is a restoration technique used in terrestrial forests, which starts with planting small vegetation patches that set the trajectory for natural propagation and recovery, resulting in large-scale restoration outcomes that require fewer resources. This concept could provide a framework for the restoration of marine seaweed forests, which are declining at unprecedented scales. We used the loss and 13-year restoration efforts of crayweed (Phyllospora comosa) forests along 70 km of Sydney’s coastline, Australia, to determine the feasibility and challenges of applied nucleation in marine forests. After transplanting events at 14 sites, 43% of transplanted sites led to the establishment and expansion of crayweed, covering ~19,000 m2 along Sydney’s coastline. Recruitment 9 months post-transplantation was negatively associated with grazing and positively related to survival of transplanted adults—a source of propagules and canopy cover in the short-term. In the longer term, crayweed expansion was positively associated with other canopy-forming seaweed species, suggesting canopy provision as an important factor influencing recovery. Small-scale efforts, such as applied nucleation, that consider factors influencing seaweed establishment and expansion can help re-establish marine forests at relevant scales.