The role of environmental driving factors in historical and projected carbon dynamics of wetland ecosystems in Alaska
- Earth, Atmospheric, and Planetary Sciences Purdue University West Lafayette Indiana 47907 USA
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska 99775 USA
- U.S. Geological Survey Alaska Cooperative Fish and Wildlife Research Unit University of Alaska Fairbanks Fairbanks Alaska 99775 USA
- Scenarios Network for Alaska and Arctic Planning International Arctic Research Center University of Alaska Fairbanks Fairbanks Alaska 99775 USA
- U.S. Department of Agriculture, Forest Service Northern Research Station Newtown Square Pennsylvania 19073 USA
- Department of Forest Resources University of Minnesota St. Paul Minnesota 55108 USA, Stinger Ghaffarian Technologies Inc., contractor to the U.S. Geological Survey Sioux Falls South Dakota 57198 USA
- U.S. Geological Survey The Earth Resources Observation Systems Center Sioux Falls South Dakota 57198 USA
- U.S. Geological Survey Reston Virginia 12201 USA
Abstract
Wetlands are critical terrestrial ecosystems in Alaska, covering ~177,000 km 2 , an area greater than all the wetlands in the remainder of the United States. To assess the relative influence of changing climate, atmospheric carbon dioxide (CO 2 ) concentration, and fire regime on carbon balance in wetland ecosystems of Alaska, a modeling framework that incorporates a fire disturbance model and two biogeochemical models was used. Spatially explicit simulations were conducted at 1‐km resolution for the historical period (1950–2009) and future projection period (2010–2099). Simulations estimated that wetland ecosystems of Alaska lost 175 Tg carbon (C) in the historical period. Ecosystem C storage in 2009 was 5,556 Tg, with 89% of the C stored in soils. The estimated loss of C as CO 2 and biogenic methane (CH 4 ) emissions resulted in wetlands of Alaska increasing the greenhouse gas forcing of climate warming. Simulations for the projection period were conducted for six climate change scenarios constructed from two climate models forced under three CO 2 emission scenarios. Ecosystem C storage averaged among climate scenarios increased 3.94 Tg C/yr by 2099, with variability among the simulations ranging from 2.02 to 4.42 Tg C/yr. These increases were driven primarily by increases in net primary production (NPP) that were greater than losses from increased decomposition and fire. The NPP increase was driven by CO 2 fertilization (~5% per 100 parts per million by volume increase) and by increases in air temperature (~1% per °C increase). Increases in air temperature were estimated to be the primary cause for a projected 47.7% mean increase in biogenic CH 4 emissions among the simulations (~15% per °C increase). Ecosystem CO 2 sequestration offset the increase in CH 4 emissions during the 21st century to decrease the greenhouse gas forcing of climate warming. However, beyond 2100, we expect that this forcing will ultimately increase as wetland ecosystems transition from being a sink to a source of atmospheric CO 2 because of (1) decreasing sensitivity of NPP to increasing atmospheric CO 2 , (2) increasing availability of soil C for decomposition as permafrost thaws, and (3) continued positive sensitivity of biogenic CH 4 emissions to increases in soil temperature.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1457077
- Alternate ID(s):
- OSTI ID: 1537553
- Journal Information:
- Ecological Applications, Journal Name: Ecological Applications Journal Issue: 6 Vol. 28; ISSN 1051-0761
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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