Mixed policies give more options in multifunctional tropical forest landscapes.
Tropical forest landscapes face competing demands for conserving biodiversity, sustaining ecosystem services and accommodating production systems such as forestry and agriculture. Land-sparing and land-sharing have emerged as contrasting strategies to manage trade-offs between production and biodiversity conservation. Both strategies are evident in land-management policies at local-to-international scales. However, studies rarely report the impacts of these strategies, assessed for multiple stakeholders and multiple ecosystem services, particularly in real landscapes. Using a case study from a high-priority region for forest protection, restoration and rural development in Central Kalimantan, Indonesia, we analysed the potential outcomes under 10 alternative policy scenarios, including land-sharing, land-sparing and mixed strategies. We used a novel optimization process integrating integer programming with conservation-planning software (Marxan with Zones) to identify production possibility frontiers (PPFs), highlighting the trade-off between smallholder agriculture and oil palm, subject to achievement of a set of carbon, timber and biodiversity conservation targets. All policy scenarios modelled proved to be capable of achieving all targets simultaneously. Most strategies resulted in an expansion of the PPF from the baseline, increasing the flexibility of land allocation to achieve all targets. Mixed strategies gave the greatest flexibility to achieve targets, followed closely by land-sparing. Land-sharing only performed better than the baseline when no yield penalties were incurred, and resulted in PPF contraction otherwise. Strategies assessed required a minimum of 29-37% to be placed in conservation zones, notably protecting the majority of remaining forest, but requiring little reforestation. Policy implications. Production possibility frontiers (PPFs) can evaluate a broad spectrum of land-use policy options. When using targets sought by multiple stakeholders within an ecosystem services framework, PPFs can characterize biophysical, socio-economic and institutional dimensions of policy trade-offs in heterogeneous landscapes. All 10 policy strategies assessed in our case study are biophysically capable of achieving all stakeholder objectives, provided at least 29-37% of the landscape is conserved for biodiversity. This novel methodological approach provides practical options for systematic analysis in complex, multifunctional landscapes, and could, when integrated within a larger planning and implementation process, inform the design of land-use policies that maximize stakeholder satisfaction and minimize conflict.