Study Shows Site, Rotation Affects Carbon Sequestration Rate

Forest modeling research at Oregon State University’s College of Forestry shows a tract’s productivity is the top factor determining the rotation time that allows for the most above-ground carbon sequestration.

Using OSU’s 11,000 acre McDonald-Dunn Research Forest as a study area, researchers inventoried more than 300 tracts known from past activities that varied widely in productivity levels. The data was run through modeling software that predicts changes in vegetation due to natural disturbances or management activities.

Using a 240-year time frame, researchers found that the most highly productive stands have the greatest carbon storage with 60-year rotations that include low intensity thinning at 40 years. Less productive sites had their best carbon storage rates at rotations ranging from roughly 80 to 100 years. However, longer rotations require multiple thinning entries to maintain overstory Douglas fir growth rates.

Researchers sought to shed some light on the debate on whether carbon sequestration is maximized with shorter rotations that are continually renewed with younger trees, or longer rotations that allow more growth between harvests.

Forest managers are increasingly seeking management decisions that meet harvest goals while also maximizing carbon sequestration rates, says Catherine Carlisle, one of the three researchers on the study. “Management techniques like determining the optimal rotation length and implementing silvicultural treatments can be powerful tools that allow managers to meet both objectives,” she adds.