Fig. 2: Cumulative CO₂e mitigation over a 100-year period for commercial forests planted at a rate of 30,000 ha year⁻¹ from 2020 to 2050, with a Hierarchical wood use strategy (a, b) or a Bioenergy wood use strategy (c, d), under Core (a, c) or Further Ambition (b, d) decarbonisation contexts.

Commercial Sitka spruce forests are modelled based on default yield class (YC) 18. Contributing factors are shown as stacked bars: process emissions, terrestrial forest carbon storage, harvested wood product (HWP) carbon storage, fossil fuel (FF) substitution (negligible in the Further Ambition context), concrete substitution and bioenergy carbon capture and storage (BECCS). Also shown (lines) are cumulative CO₂e mitigation trends for conservation forests planted at the same rate, ranging from semi-natural 100% broadleaf (YC 4), through a 50:50 mixed conifer:broadleaf forest (YC 11) to an unharvested 100% conifer forest (YC 18). These lines represent terrestrial forest carbon storage only, and the C100-18 forest provides a direct comparison of cumulative mitigation that could be achieved by YC 18 conifers if they are not harvested.