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Title: Attaining whole-ecosystem warming using air and deep-soil heating methods with an elevated CO<sub>2</sub> atmosphere

This paper describes the operational methods to achieve and measure both deep-soil heating (0–3 m) and whole-ecosystem warming (WEW) appropriate to the scale of tall-stature, high-carbon, boreal forest peatlands. The methods were developed to allow scientists to provide a plausible set of ecosystem-warming scenarios within which immediate and longer-term (1 decade) responses of organisms (microbes to trees) and ecosystem functions (carbon, water and nutrient cycles) could be measured. Elevated CO 2 was also incorporated to test how temperature responses may be modified by atmospheric CO 2 effects on carbon cycle processes. The WEW approach was successful in sustaining a wide range of aboveground and belowground temperature treatments (+0, +2.25, +4.5, +6.75 and +9 °C) in large 115 m 2 open-topped enclosures with elevated CO 2 treatments (+0 to +500 ppm). Air warming across the entire 10 enclosure study required ~90 % of the total energy for WEW ranging from 64 283 mega Joules (MJ) d –1 during the warm season to 80 102 MJ d –1 during cold months. Soil warming across the study required only 1.3 to 1.9 % of the energy used ranging from 954 to 1782 MJ d –1 of energy in the warm and cold seasons,more » respectively. The residual energy was consumed by measurement and communication systems. Sustained temperature and elevated CO 2 treatments were only constrained by occasional high external winds. This paper contrasts the in situ WEW method with closely related field-warming approaches using both aboveground (air or infrared heating) and belowground-warming methods. It also includes a full discussion of confounding factors that need to be considered carefully in the interpretation of experimental results. As a result, the WEW method combining aboveground and deep-soil heating approaches enables observations of future temperature conditions not available in the current observational record, and therefore provides a plausible glimpse of future environmental conditions.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [2] ; ORCiD logo [1] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Harvard Univ., Cambridge, MA (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Biogeosciences (Online)
Additional Journal Information:
Journal Name: Biogeosciences (Online); Journal Volume: 14; Journal Issue: 4; Journal ID: ISSN 1726-4189
Publisher:
European Geosciences Union
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
Work for Others (WFO); USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1344998