Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers |
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| Authors: | Jennifer J. Follstad Shah John S. Kominoski Marcelo Ardón Walter K. Dodds Mark O. Gessner Natalie A. Griffiths Charles P. Hawkins Sherri L. Johnson Antoine Lecerf Carri J. LeRoy David W. P. Manning Amy D. Rosemond Robert L. Sinsabaugh Christopher M. Swan Jackson R. Webster Lydia H. Zeglin |
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| Affiliation: | 1. Environmental and Sustainability Studies/Department of Geography, University of Utah, Salt Lake City, UT, USA;2. Department of Watershed Sciences, Utah State University, Logan, UT, USA;3. Department of Biological Sciences, Florida International University, Miami, FL, USA;4. Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA;5. Division of Biology, Kansas State University, Manhattan, KS, USA;6. Department of Experimental Limnology, Leibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany;7. Department of Ecology, Berlin Institute of Technology (TU Berlin), Berlin, Germany;8. Climate Change Science Institute and Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA;9. Pacific Northwest Research Station, US Forest Service, Corvallis, OR, USA;10. Université de Toulouse, UPS, INP, CNRS, EcoLab (Laboratoire d’écologie Fonctionnelle et Environnement), Toulouse, France;11. Environmental Studies Program, The Evergreen State College, Olympia, WA, USA;12. School of Environment and Natural Resources, Ohio State University, Columbus, OH, USA;13. Odum School of Ecology, University of Georgia, Athens, GA, USA;14. Department of Biology, University of New Mexico, Albuquerque, NM, USA;15. Department of Geography and Environmental Systems, University of Maryland‐Baltimore County, Baltimore, MD, USA;16. Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA |
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| Abstract: | Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. Here, we synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by the activation energy (Ea, in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which Ea could be calculated. Higher values of Ea were correlated with lower‐quality litter, but these correlations were influenced by a single, N‐fixing genus (Alnus). Ea values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the Ea was 0.34 ± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5–21% with a 1–4 °C rise in water temperature, rather than a 10–45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in Ea values for these regions (0.75 ± 0.13 eV and 0.27 ± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that Ea values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale. |
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| Keywords: | activation energy breakdown carbon cycling climate change detritivore leaf chemistry metabolic theory microbe organic matter temperature sensitivity |
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