Optimal rotation period for Pinus tabuliformis plantations under different carbon policy scenarios

Objective Forests exhibit externalities and face market failures. By introducing carbon policies and implementing appropriate management strategies, it is possible to maximize multi-objective benefits, fully harness the carbon sequestration potential of forests, and contribute to achieving the “Dual Carbon” goals.

Method This paper examines Pinus tabuliformis plantations in Shaanxi Province, China. Stand growth models were constructed using analytical timber data based on the Richards equation; carbon stock growth models were built using the conversion factor continuous function method. Based on the Faustmann-Hartman model, the land expectation value (LEV) and optimal rotation period were simulated under different carbon policy scenarios. Carbon storage of forest stands was calculated at various carbon prices under both carbon tax and subsidy policies. Sensitivity analysis was employed to quantitatively assess the impacts of different economic parameters on LEV and optimal rotation period.

Result (1) At a discount rate of 4%, carbon price of 50 CNY/t, and timber price of 980 CNY/m³, the optimal rotation period was 56.2 years with timber revenue only, yielding a LEV of 11 203 CNY/ha. Introducing a carbon subsidy policy extended the optimal rotation period by 0.4 years and increased LEV to 11 935 CNY/ha. The addition of a carbon tax policy did not change the rotation period but reduced LEV to 11 499 CNY/ha due to carbon loss. (2) Incentive-based carbon policies enhanced forest carbon storage: a 1-unit increase in carbon price raises carbon storage per hectare by 3%. (3) As the discount rate increases from 1% to 5%, the optimal rotation period shortened progressively. When the timber price increased from 700 CNY/m³ to 1 200 CNY/m³, the optimal rotation period remained almost unchanged.

Conclusion Hybrid carbon policies can effectively extend the rotation period and increase stand carbon storage, thereby promoting the sustainable development of forests. Moderately reducing the discount rate can extend the optimal rotation period, enhancing forest carbon sequestration and other ecosystem services.