18 July 2016
Estimating heterotrophic respiration at large scales: Challenges, approaches, and next steps.
This study proposed improving representation of heterotrophic respiration (HR) in Earth system models (ESMs) by grouping metabolism and flux characteristics across space and time.
The scientists argued for development of Decomposition Functional Types (DFTs), analogous to plant functional types (PFTs), for use in global models. They applied cluster analysis to produce example DFTs based on the global variability in 11 biotic and abiotic factors that influence decomposition processes.
Heterotrophic respiration, 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 the 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, the scientists suggest that a useful step to improve this situation is the development of DFTs. Analogous to 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. The team applied cluster analysis to show how annual HR can be broken into distinct groups associated with global variability in biotic and abiotic factors, and they demonstrated that these groups are distinct from, but complementary to, PFTs. In this position paper, they suggested priorities for next steps to build a foundation for DFTs in global models to provide the ecological and climate change communities with robust, scalable estimates of HR.
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Renu Joseph, Daniel Stover, SC-23.1
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Ben Bond-Lamberty (PNNL), Forrest M. Hoffman (ORNL), and Jitendra Kumar (ORNL)
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This research is the product of a working group on heterotrophic respiration led by M. Harmon and sponsored by the National Science Foundation, which funded meeting and travel expenses. B. Bond-Lamberty was supported by the Terrestrial Ecosystem Sciences program of the Office of Biological and Environmental Research (BER), within the U.S. Department of Energy (DOE) Office of Science. The Pacific Northwest National Laboratory (PNNL) is operated for DOE by Battelle Memorial Institute under contract DE-AC05-76RL01830. R. Vargas and AD McGuire acknowledge support from the U.S. Department of Agriculture (2014-67003-22070) and U.S. Geological Survey, respectively. F.M. Hoffman and J. Kumar were supported by the Biogeochemistry–Climate Feedbacks (BGC Feedbacks) Scientific Focus Area and the Next-Generation Ecosystem Experiments (NGEE)–Tropics projects, which are sponsored by the DOE Office of Science, BER, Regional & Global Climate Modeling, and Terrestrial Ecosystem Science programs in the BER Climate and Environmental Sciences Division. FMH and JK’s contributions were authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with DOE.
Bond-Lamberty, B., D. Epron, J. Harden, M.E. Harmon, F.M. Hoffman, J. Kumar, A.D. McGuire, and R. Vargas. “Estimating heterotrophic respiration at large scales: Challenges, approaches, and next steps.” Ecosphere 7(6), e01380 (2016). [DOI:10.1002/ecs2.1380].