March 19, 2018
Portfolio of Land Use Strategies Can Increase Future Carbon Sequestration in Moist Temperate Forests
High carbon density forests have potential to increase carbon sequestration, reduce forest emissions.
A team of scientists at Oregon State University and University of Idaho studied the relative merits of strategies to mitigate carbon dioxide emissions through forestry activities in the Pacific Northwest, where wet forests can store carbon for over 800 years and are at relatively low risk for carbon losses due to mortality. They created an analysis framework that integrates observations with high-resolution Earth system modeling and a life cycle assessment to identify strategies that increased forest carbon sequestration and reduced net emissions by 2050 and 2100.
Reforestation, afforestation, lengthened harvest cycles, and restricted harvest on public lands are expected to increase carbon sequestration by 2100. Using harvest residues for bioenergy production increases net emissions for 50 years, reducing mitigation effectiveness.
Researchers found that carbon uptake in the region is expected to increase under future environmental conditions, in spite of increased fire emissions in the dry ecoregions. The study provides a template for evaluating regional mitigation options for reducing carbon dioxide emissions and increasing forest net ecosystem carbon balance. The analysis framework has potential for use in other temperate regions.
Temperate rainforests represent some of the highest biomass forests in the world and can store carbon in trees for 800 years or more. By 2100, simulations show increased net carbon uptake in the wet ecoregions far outweighs losses from fire and drought in semiarid ecoregions. Reforestation, afforestation, lengthened harvest cycles on private lands, and restricting harvest on public lands increase net ecosystem carbon balance (NECB) 56% by 2100, with the latter two actions contributing the most. The largest potential is in the wet ecoregions. Resultant co-benefits included water availability and biodiversity, primarily from increased forest area, age, and species diversity. Converting 127,000 hectares (ha) of irrigated grass crops to native forests could decrease irrigation demand by 233 billion m3 per year. Utilizing harvest residues for bioenergy production instead of leaving them in forests to slowly decompose increased emissions over the next 50 years, reducing mitigation effectiveness. Reserving forest carbon on public lands reduced emissions compared with storage in wood products because the residence time is more than twice that of wood products. Hence, temperate forests with high carbon densities and lower vulnerability to mortality have substantial potential for reducing forest sector emissions.
Oregon State University, Corvallis
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
This research was supported by the Office of Biological and Environmental Research within the U.S. Department of Energy (Grant DE-SC0012194) and Agriculture and Food Research Initiative of the U.S. Department of Agriculture National Institute of Food and Agriculture (Grants 2013-67003-20652, s2014-67003-22065) for the North American Carbon Program studies, “Carbon cycle dynamics within Oregon’s urban-suburban-forested-agricultural landscapes.”
Law, B. E., T. W. Hudiburg, L. T. Berner, L.T., and J. J. Kent, et al. "“Land use strategies to mitigate climate change in carbon dense temperate forests". Proceedings of the National Academy of Sciences USA 115 (14), 3663–3668 (2018). https://doi.org/10.1073/pnas.1720064115.