Tropical mixed-species plantations can outperform monocultures in terms of carbon sequestration and economic return

Tropical reforestation is an important strategy to mitigate the global climate crisis through the sequestration of CO2. Together with increasing CO2 prices, carbon storage becomes increasingly relevant for commercial reforestations. Due to higher productivity, mixed-species reforestations have been suggested for carbon plantings. Yet, current studies comparing mixtures and monocultures lack an in-depth comparison of economic and carbon sequestration potentials. Moreover, their economic valuations do not consider carbon payments and differences in forest management. Using a simulation-optimization approach, we compared the economic and carbon sequestration performance of commercial mixed-species stands and monocultures in Costa Rica. Mixed-species stands outperformed their monoculture peers by net present value (NPV) up to 3135 USD/ha if only timber sales were considered, or 3500–16,800 USD/ha if carbon payments were also considered (at a discount rate of 8%). When managed solely for carbon sequestration, the best-performing mixture achieved a mean stand carbon 7% above the best-performing monoculture. The results were sensitive to the comparison baseline applied. The results of this study suggest that tropical mixed-species plantations can be a competitive alternative to monocultures. Forest investors could benefit from establishing mixed-species plantations when reforesting plantation sites where species-specific site suitability is uncertain, or when working with lesser-studied tree species.