From rapid establishment to recruitment limitation: Successional dynamics of the exotic Sonneratia apetala in the Pearl River Estuary, China

Despite major successes in mangrove restoration in China, the widespread use of the exotic Sonneratia apetala has triggered growing concerns about its long-term invasive impacts. Yet, how naturally expanding S. apetala populations spread, self-regulate and interact with native mangroves under real coastal engineering scenarios remains poorly understood. A major obstacle is the lack of stand‑scale data of spread rate and spatial pattern, typically due to limited long‑term monitoring. Here, we investigated the successional dynamics of a 12-year-old, naturally established S. apetala stand in the Pearl River Estuary, China. By integrating population structure and demography with spatial distribution and clustering patterns—using size classes as proxies for age groups, a space-for-time substitution approach, and spatial point pattern analysis—we identified a distinct two-phase successional trajectory of S. apetala populations driven by the opportunity–capacity–constraint framework: (i) rapid establishment, in which bare mudflats created by coastal engineering (opportunity) were promptly colonized and subsequently dominated via fast growth and dispersal (capacity); (ii) recruitment limitation, emerging within roughly six years after natural colonization, wherein density-dependent dispersal inhibition (constraint) suppressed juvenile recruitment, resulting in spatial segregation among age groups and from native species ( Aegiceras corniculatum and Acanthus ilicifolius ). This two-phase dynamic enabled S. apetala to rapidly occupy and monopolize open habitats to form monodominant stands, posing adverse effects on native mangrove biodiversity, yet its expansion is ultimately self-limited. Our findings thus reconcile S. apetala ’s utility in shoreline stabilization against its ongoing ecological risks. By elucidating the successional trajectory, this study advances predictive modeling of mangrove invasions, informs adaptive restoration strategies, and supports management decisions that balance short-term engineering benefits with the long-term conservation of native mangrove ecosystems. • Space‑for‑time and point‑pattern analyses reconstructed stand development. • Recruitment limitation followed rapid establishment to curb uncontrolled expansion. • Phase-specific management should balance utilization with invasion threats.