Applied nucleation promotes recovery of New Zealand raised bog vegetation toward a reference community

Abstract

Abstract Introduction Applied nucleation aims to restore degraded ecosystems efficiently by establishing vegetation patches that increase in biodiversity and extent through natural dispersal and facilitation. Although widely tested in terrestrial ecosystems, its long‐term outcomes in wetlands remain poorly understood, particularly how restored communities develop over time and how post‐restoration trajectories compare with reference ecosystems. Objectives We evaluated outcomes after 21 years of an applied nucleation experiment to restore a mined restiad raised bog in northern New Zealand. Methods Nuclei were established as raised peat islands (approximately 10 m diameter) and seeded with the early‐successional shrub mānuka ( Leptospermum repo ) in 2002. Vegetation composition and peat properties were assessed within nuclei and the surrounding matrix at three distances from an adjacent natural reference peatland. Nuclei plots were surveyed after 2, 9, and 21 years, while matrix and natural peatland plots were measured after 21 years. Results Mānuka successfully established, followed by the establishment of peat‐forming restiad species bamboo rush ( Sporadanthus ferrugineus ) and wire rush ( Empodisma robustum ), the latter one of three species facilitated by mānuka. Beta diversity among nuclei increased over time, reflecting continued recruitment and increasing community heterogeneity. Plant community composition within nuclei became progressively more similar to the natural peatland, and after 21 years, nuclei supported higher diversity and greater compositional similarity to the natural peatland than did surrounding matrix areas, which also showed recovery toward the reference community. However, persistent differences in peat bulk density, water content, and nutrient concentrations revealed enduring legacies of mining disturbance. Conclusions Applied nucleation can initiate ecological recovery in degraded peatlands. Establishment of early‐successional nurse species facilitates the return of peat‐forming plants and promotes recovery toward a reference community, even where disturbance legacies persist.