title: A framework for assessing global change risks to forest carbon stocks in the United States.
abstract: Among terrestrial environments, forests are not only the largest long-term sink of atmospheric carbon (C), but are also susceptible to global change themselves, with potential consequences including alterations of C cycles and potential C emission. To inform global change risk assessment of forest C across large spatial/temporal scales, this study constructed and evaluated a basic risk framework which combined the magnitude of C stocks and their associated probability of stock change in the context of global change across the US. For the purposes of this analysis, forest C was divided into five pools, two live (aboveground and belowground biomass) and three dead (dead wood, soil organic matter, and forest floor) with a risk framework parameterized using the US's national greenhouse gas inventory and associated forest inventory data across current and projected future Köppen-Geiger climate zones (A1F1 scenario). Results suggest that an initial forest C risk matrix may be constructed to focus attention on short- and long-term risks to forest C stocks (as opposed to implementation in decision making) using inventory-based estimates of total stocks and associated estimates of variability (i.e., coefficient of variation) among climate zones. The empirical parameterization of such a risk matrix highlighted numerous knowledge gaps: 1) robust measures of the likelihood of forest C stock change under climate change scenarios, 2) projections of forest C stocks given unforeseen socioeconomic conditions (i.e., land-use change), and 3) appropriate social responses to global change events for which there is no contemporary climate/disturbance analog (e.g., severe droughts in the Lake States). Coupling these current technical/social limits of developing a risk matrix to the biological processes of forest ecosystems (i.e., disturbance events and interaction among diverse forest C pools, potential positive feedbacks, and forest resiliency/recovery) suggests an operational forest C risk matrix remains elusive.
authors.affiliation: US Department of Agriculture, Forest Service, Northern Research Station, St. Paul, Minnesota, United States of America.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Woodall
authors.forename: Grant M
authors.initials: GM
authors.lastname: Domke
authors.forename: Karin L
authors.initials: KL
authors.lastname: Riley
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Oswalt
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Crocker
authors.forename: Gary W
authors.initials: GW
authors.lastname: Yohe
mesh_terms: D002244:Carbon; D057486:Carbon Cycle; D002245:Carbon Dioxide; D057231:Climate Change; D017753:Ecosystem; D014197:Trees; D014481:United States; D014934:Wood
chemical_list: D002245:Carbon Dioxide; D002244:Carbon
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