Summary of Oregon Global Warming Commission
Forest Carbon Accounting Report 2018
1. Oregon’s forest rival tropical rainforests in terms of carbon density and quantity of storage.
2. Current analysis suggests that treatments which include medium to heavy thinning result in reduced carbon stores that do not recover in any meaningful time periods.
3. Ecosystem carbon accounting methods identify distinct “pools” of forest carbon. In this analysis we use five USFS FIA-defined pools: (1) above-ground live trees, (2) above-ground dead trees, (3) downed and woody material, (4) forest floor, and (5) soil carbon.
4. An analysis done by the Forest Service of FIA data put soil carbon at 47 percent and live trees at 35 percent as the largest pools across all Oregon ecoregions.
5. A second analysis done by OSU School of Forestry scientists using FIA data plus additional sources of data estimates the shares of carbon in soil and live trees at 42 percent and 41 percent respectively. Soil carbon quantities are assumed to be relatively stable, while live and dead/decaying trees are the primary interface for exchanging significant amounts of carbon between the forest and the atmosphere.
6. Almost three quarters (73 percent) of net carbon stores are found in publicly-owned (mostly federal) Oregon forests comprising 65 percent of total forested acres; carbon is increasing on these lands.
7. However, on average, for the period 2001-2015, forest fires in Oregon appears to have released around 5.3 million tons CO2e annually (Law et. al, 2018) to the atmosphere, or a quantity equal to about 9 percent of all Oregon non-forest greenhouse gas emissions. This is substantially less than the net amounts of carbon annually withdrawn from the atmosphere by Oregon’s forests during this same period.
8. Based on credible evidence today, forest harvest does not appear to result in net carbon conservation when compared to carbon retention in unharvested forests.
9. The evidence is that significant amounts of carbon are lost at each stage in timber harvest and processing into wood products, and in decomposition at the end of useful product life. The forest stores and conserves carbon more effectively and for longer periods of time than do most products derived from harvested trees.
10. Based on available evidence today, forest harvest does not result in material carbon conservation; rather it results in net carbon emissions measured against leaving forests unharvested. Notwithstanding improvements in more efficient utilization of harvested forest fiber, significant amounts of carbon are lost at each stage in timber harvest and in decomposition at the end of useful product life. Meanwhile, forests actively withdraw carbon from the atmosphere, and store and conserve it more effectively and for longer periods of time than do products derived from harvested trees.
11. That said, extractive logging for all purposes – that is, harvesting and removing (mostly) live trees with their carbon stores – will reduce the total amount of carbon that otherwise might be expected to remain in long-term forest storage.
12. Harvest-related loss of forest carbon stores appears to be substantially in excess of fire-related carbon emissions; by one analysis, harvest reduced Oregon in-forest carbon stores by 34 percent between 2001 and 201519 (Law et al. 2018) if compared to a non-harvest base case.
13. The 2011 OSU study (Clark et al, 2011) from which the figure on the following page is taken, looked at the carbon consequences of different levels of thinning. Carbon accumulations continue under a “no thin” policy, while light thinning requires 15 years to recover pre-thin carbon levels. The analysis continues through an intermediate “financial break-even” thin (remove all trees less than 7” DBH24 and 20 percent of trees 7”-20” DBH) that required a 25 to 40 year carbon recovery period; and a heavy thin that fails to recover pre-thin carbon levels over a 50 year (or longer) period.
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