Community-ecosystem interactions control plant biodiversity change before and after mangrove restoration.

Restoring biological diversity and ecosystem function requires understanding how introduced species interact with one another and their environments. The most prevalent and challenging scenarios involve multiple invasive species whose traits feedback through ecosystem processes. However, research into these systems often focuses on either community dynamics or ecosystem properties, rather than their interactions, limiting understanding of what causes biodiversity changes before and after restoration. Leveraging insights from theory and management of single-species invasions driven by feedback between plant litter and germination success, we documented the structure of a disturbed mangrove ecosystem and tested causal hypotheses for community and ecosystem change both in microcosms and across the landscape. Before restoration, competing invasive trees generated litter that facilitated the dominance of a single recently introduced species. After experimental restoration, native species seedling cover and richness increased only when removing invasive trees and their litter, supporting interacting community and ecosystem effects as the primary drivers of biodiversity change. Effective restoration of multiply-invaded ecosystems is possible when simple interventions follow causal hypotheses supported by theoretical mechanisms.