Institutional disconnects and sustainability outcomes in Co‑managed forest protected areas

Co-management of forest protected areas (FPAs) is widely promoted in tropical Asia to integrate community participation into biodiversity conservation, yet multi-site evaluations remain scarce. This study assesses sustainability governance across ten co-managed FPAs in Bangladesh using a four-pillar framework – institutional, economic, ecological, and social – operationalised via 49 indicators administered to 262 respondents from four stakeholder groups. This study employed non-parametric tests, Spearman correlation, bootstrap confidence intervals, and a sensitivity analysis excluding the site where co-management was suspended in 2019. The grand mean overall Sustainability Index (SI) reached 0.523, with no site achieving high governance performance (SI ≥ 0.75) after two decades of implementation. Outcomes were statistically uniform across all nine active FPAs, demonstrating that the performance ceiling reflects a national structural constraint rather than site-specific management failure. The economic pillar recorded the lowest score (mean SI = 0.348) and the largest respondent-type perception gap (η2 = 0.199), revealing a pronounced accountability deficit between governance bodies and forest-dependent communities. Furthermore, the institutional pillar was structurally disconnected from the three outcome pillars (all ρ ≤0.333), while economic, ecological, and social pillars formed a co-evolving triad (ρ = 0.644–0.705). These findings indicate that co-management has produced governance formalisation without governance function. Translating participatory structures into measurable outcomes requires reforming the Protected Area Management Rules 2017 through separating regulatory and executive authority within governance committees. Broadly, this validated four-pillar framework provides a transferable diagnostic tool to evaluate co-management effectiveness across tropical forest governance systems and support Sustainable Development Goals 15 and 16.