Background/Question/Methods Natural climate solutions, particularly afforestation, have been proposed as cost-effective options to achieve climate stabilization goals. An important research gap exists: the economic implications of the type and locations of afforestation efforts and their consequences for global GHG emissions mitigation potential. Despite numerous studies that debate the use of natural or plantation forests and how much land is available for conversion, they often lack economic analyses to evaluate the sectoral impacts on timber and biomass prices, product demand, and leakage. We address that gap by modelling afforestation approaches proposed in ecological literature and additional potential forest-use and planting constraints, such as the strategic use of plantation forests in certain regions to meet timber and carbon sequestration demand. We also assess how complete protection of ecological hotspots would impact the global timber market relative to current protected area. Understanding the role of forest management in achieving 1.5° or 2°C goals and the attendant economic and sectoral implications are critical to evaluating the policy alternatives for impacts beyond biodiversity considerations. We use the Global Timber Model, a dynamic optimization forest management model designed to examine global timber supply, carbon stocks, and forest area to assess the policy trade-offs, carbon sequestration potential, and cost-effectiveness of afforesting a mix of natural and plantation forests. Further, we test our findings under a range of forest use and climate policy scenarios. Results/Conclusions Our results assess afforestation/reforestation policies by estimating harvests, timberland management intensity, and plantation establishment. Forest management approaches that restrict the use of plantation forests to meet timber and carbon sequestration demand increase timber prices and reduce total forest carbon sequestration. Relaxing that constraint, planting trees in temperate regions to meet demand for timber products enables protection of tropical natural forests and biodiversity through the reduced risk of tropical deforestation. We conclude that climate change mitigation, biodiversity, and timber sector goals can be jointly achieved through a combination of forest management policies. Harvests, timber prices, forest carbon, and forest area are highest under more stringent climate reduction scenarios. Moreover, total forest carbon and forest area are highest under scenarios that do not constrain the use of plantation forests. Total forest carbon stocks ranged from 361–543 GtC under our policy scenarios, a 38-114% increase from today. On the contrary, policies increased roundwood prices to ranges of $410-1,081, with prices being highest under the more restrictive reforestation policies.
