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Title: Estimating heterotrophic respiration at large scales: Challenges, approaches, and next steps

Heterotrophic respiration (HR), the aerobic and anaerobic processes mineralizing organic matter, is a key carbon flux but one impossible to measure at scales significantly larger than small experimental plots. This impedes our ability to understand carbon and nutrient cycles, benchmark models, or reliably upscale point measurements. Given that a new generation of highly mechanistic, genomic-specific global models is not imminent, we suggest that a useful step to improve this situation would be the development of Decomposition Functional Types (DFTs). Analogous to plant functional types (PFTs), DFTs would abstract and capture important differences in HR metabolism and flux dynamics, allowing modelers and experimentalists to efficiently group and vary these characteristics across space and time. We argue that DFTs should be initially informed by top-down expert opinion, but ultimately developed using bottom-up, data-driven analyses, and provide specific examples of potential dependent and independent variables that could be used. We present an example clustering analysis to show how annual HR can be broken into distinct groups associated with global variability in biotic and abiotic factors, and demonstrate that these groups are distinct from (but complementary to) already-existing PFTs. A similar analysis incorporating observational data could form the basis for future DFTs. Finally, wemore » suggest next steps and critical priorities: collection and synthesis of existing data; more in-depth analyses combining open data with rigorous testing of analytical results; using point measurements and realistic forcing variables to constrain process-based models; and planning by the global modeling community for decoupling decomposition from fixed site data. Lastly, these are all critical steps to build a foundation for DFTs in global models, thus providing the ecological and climate change communities with robust, scalable estimates of HR.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [5]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Univ. de Lorraine, Vandoeuvre-les-Nancy (France)
  3. United States Geological Survey, Menlo Park, CA (United States)
  4. Oregon State Univ., Corvallis, OR (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Univ. of Alaska Fairbanks, Fairbanks, AK (United States)
  7. Univ. of Delaware, Newark, DE (United States)
Publication Date:
OSTI Identifier:
1259577
Grant/Contract Number:
AC05-00OR22725
Type:
Published Article
Journal Name:
Ecosphere
Additional Journal Information:
Journal Volume: 7; Journal Issue: 6; Journal ID: ISSN 2150-8925
Publisher:
Ecological Society of America
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC); Work for Others (WFO)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; heterotropic respiration; carbon cycle; modeling