title: From sink to source: Regional variation in U.S. forest carbon futures.
abstract: The sequestration of atmospheric carbon (C) in forests has partially offset C emissions in the United States (US) and might reduce overall costs of achieving emission targets, especially while transportation and energy sectors are transitioning to lower-carbon technologies. Using detailed forest inventory data for the conterminous US, we estimate forests' current net sequestration of atmospheric C to be 173 Tg yr(-1), offsetting 9.7% of C emissions from transportation and energy sources. Accounting for multiple driving variables, we project a gradual decline in the forest C emission sink over the next 25 years (to 112 Tg yr(-1)) with regional differences. Sequestration in eastern regions declines gradually while sequestration in the Rocky Mountain region declines rapidly and could become a source of atmospheric C due to disturbances such as fire and insect epidemics. C sequestration in the Pacific Coast region stabilizes as forests harvested in previous decades regrow. Scenarios simulating climate-induced productivity enhancement and afforestation policies increase sequestration rates, but would not fully offset declines from aging and forest disturbances. Separating C transfers associated with land use changes from sequestration clarifies forests' role in reducing net emissions and demonstrates that retention of forest land is crucial for protecting or enhancing sink strength.
authors.affiliation: United States Department of Agriculture Forest Service, PO Box 8008 North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Wear
authors.affiliation: United States Department of Agriculture Forest Service, 4700 Old Kingston Pike, Knoxville, TN 37919, USA.
authors.forename: John W
authors.initials: JW
authors.lastname: Coulston
mesh_terms: D002244:Carbon; D057965:Carbon Sequestration; D017753:Ecosystem; D004784:Environmental Monitoring; D065928:Forests; D014481:United States
chemical_list: D002244:Carbon