Quantifying carbon additionality for uneven-aged forests

Abstract

Forests can be managed to sequester atmospheric carbon in addition to producing timber. Forest carbon represents a nature-based solution to climate change and global warming. To internalize the positive externality (social benefit) of forest carbon, additionality must be defined and quantified. In this study, the discounted cash flow approach is applied to an uneven-aged sugar maple forest at a steady state to measure carbon additionality. Carbon credits are generated from the marginal forest growth, while a carbon release penalty is incurred by a harvest. The business-as-usual scenario is defined by a shorter harvest cycle, while an alternative carbon scenario is defined by a longer one. Then, additionality is defined by the difference in the net present value of carbon sequestration on a perpetual basis between the two scenarios. Compared with previous analysis on even-aged southern pine plantations, there is some evidence that the uneven-aged sugar maple forest is less economically effective in carbon offset as indicated by the benefit-cost ratio.