Net effect of forest harvest on CO₂ emissions to the atmosphere: a sensitivity analysis on the influence of time

Forests can be harvested and regrown on a sustainable basis while harvested material is used to either store carbon in long-lived wood products or to displace carbon dioxide emissions from fossil fuel combustion. To frame the question whether this implies that harvesting forests is an effective strategy for mitigating the increase of carbon dioxide in the atmosphere, we use a carbon accounting model to ask how long it takes to return to the original carbon balance after a forest stand is clear-cut harvested for biofuels and other forest products. Although the numerical solution depends on a great variety of site-specific model input parameters, it is clear that the system will not return to its original carbon balance for a very long time (perhaps centuries) unless forest products are produced and used efficiently. Especially when the cycle of producing forest products involves initial harvest of a forest stand with a large standing stock of biomass, there is likely to be a long-standing debit in terms of net carbon emissions to the atmosphere. On the other hand, if forest harvest is produced and used with high efficiency and the rate of regrowth is high, potential carbon benefits can be very high over time and it is possible that there is never a carbon debit with respect to forest protection, even immediately following harvest. Any intent to use forest harvesting to help mitigate the buildup of carbon dioxide in the earth’s atmosphere should be able to demonstrate that the forest regrowth and product use can compensate for the loss of carbon from the forest as a result of the initial harvest.