Tropical Mixed-Species Plantations Can Outperform Monocultures in Terms of Carbon Sequestration and Economic Return

Large-scale reforestations in the tropics have become an important strategy to mitigate the global climate crisis through the sequestration of CO2. Mixed-species reforestations have been suggested for carbon plantings. In the context of commercial plantation forestry, the establishment of mixed-species plantations should be addressed under the consideration of competitiveness with existing monoculture practices. In this study, we compared the economic and carbon sequestration performance of commercial mixed-species stands and monocultures for two plantation sites in Costa Rica using a simulation-optimization approach. We found that mixed-species stands outperformed their monoculture peers by net present value (NPV) up to 3135 USD/ha if only timber sales were considered, or up to 3500-16800 USD/ha if the sale of carbon credits was considered. When managed solely for carbon sequestration the best-performing mixture achieved a mean stand carbon 7% above the best-performing monoculture. However, whether mixed stands outperformed monocultures was highly sensitive to the chosen baseline for comparison. Under perfect certainty and along with limited knowledge of the management of mixtures, commercial mixed stands will rarely outperform the best-performing monocultures. Under uncertainty – e.g. with regards to site suitability – or if forest owners prefer a diversified species portfolio, mixed stands might consistently outperform monocultures