Are payment for ecosystem services fulfilling their promise? A review of mechanisms in Maritime Southeast Asia

Abstract Maritime Southeast Asia faces accelerating environmental degradation driven by rapid economic development and land‐use change. Payment for ecosystem services (PES) is often promoted to incentivise conservation while supporting rural livelihoods, yet evidence on the spread, design and effectiveness of PES in the region remains limited. We combined desk‐based identification and verification of PES mechanisms with a systematic review of peer‐reviewed studies that assessed environmental and socio‐economic outcomes, enabling comparison between the set of verified active mechanisms and the smaller set of evaluated cases. We identified 19 implemented, verified and active PES mechanisms initiated between 1925 and 2022, concentrated in the Philippines and Indonesia. No mechanisms could be verified as currently active in Malaysia, Singapore, Brunei or Timor‐Leste, and verification was often constrained by fragmented documentation and inactive or unverified schemes. Four broad patterns emerged: dominance of watershed protection, a shift from community‐based to more market‐linked arrangements, growth of multi‐stakeholder coalitions and diverse incentive types (cash, in‐kind and community development benefits). Peer‐reviewed outcome evidence is sparse and uneven (eight studies total), with only one outcome study from the Philippines and the remainder focused on Indonesia. Environmental outcomes are context‐dependent and often modest, while socio‐economic outcomes range from empowerment and poverty reduction to concerns about equity and elite capture. Attribution to PES remains uncertain in most cases due to heterogeneous indicators and limited use of counterfactual or longitudinal designs. Practical implication : These findings highlight the need for practical solutions to improve PES effectiveness in the region, including stronger monitoring systems, inclusive governance arrangements and deeper institutional embedding, alongside expanded empirical research using longitudinal and counterfactual designs to assess effectiveness and equity over time.