Dr. Steve Prisley, Principal Research Scientist for the National Council for Air and Stream Improvement (NCASI) has run modeling scenarios based on published studies in order to compare the net impact on carbon sequestration of reducing or eliminating timber harvest on 5.4 million acres of privately-owned Douglas-fir forests in Oregon and Washington (which is 28 percent of all Douglas-fir forests in that area) against maintaining status quo harvest levels or even increasing harvest levels to match annual forest growth.
Many environmental groups and even some scientific researchers have attempted to make the argument that the best way to increase carbon stocks at a low cost is to reduce or eliminate harvest and grow older forests. Prisley has identified that the problem with that conclusion is that it fails to address all factors which impact net sequestration (carbon removed from the atmosphere against emissions). In particular, a full analysis would look beyond the change in forest carbon stocks and factor in the lifecycle of the carbon-containing products derived from harvested timber, comparative emissions from substituting an alternative product like concrete or steel for wood, and the geographic displacement of foregone harvest to another region (leakage).
Prisley’s models rely on United States Forest Service Forest Inventory Analysis data for 10-year old forests projecting forward for 100 years, using published models for decay functions. He then applies substitution and leakage factors from published research. Of the four scenarios that he has modeled: one that maintains status quo harvest levels (baseline), one that increases harvest levels to match annual growth of the forest (balanced), one that reduces harvest by 16 percent (reduced), and one that eliminates harvest entirely (no harvest), increased harvest is shown to maximize net sequestration.
If one simply looks at forest carbon stocks, reducing or eliminating harvest undeniably increases forest carbon stocks over 100 years. But when emissions associated with substitution are included and when leakage is factored in at a reasonable rate, net sequestration, which is of far greater consequence than merely looking at carbon stocks, alone, is maximized in the increased harvest scenarios. These factors also cause the no-harvest scenario to actually becomes a net carbon emitter after 30-90 years depending on the strength of the substitution factor that is used.
Furthermore, Prisley’s models reveal the true cost to a landowner of eliminating or reducing harvest as a function of simply lost stumpage value to make the case that forest carbon offsets are simply not economically feasible. He has determined that the cost of eliminating harvest pencils out to roughly $230 per metric ton of CO2e stored, and $198 per metric ton of CO2e stored in a reduced-harvest scenario. This far outstrips even the prohibitive cost of direct carbon capture at $70-100 per metric ton of CO2e stored.
In conclusion, increasing harvest to match annual growth or maintaining status quo harvest levels actually provides more climate mitigation bang-for-the-buck, as alternative management that reduces harvest not only decreases net sequestration, but stores carbon at a true cost that is far greater than even cost-prohibitive carbon capture technologies. It turns out that business as usual actually can be more climate friendly than ill-conceived approaches that seek to lock up carbon on the forest floor.
