Abstract
We used a natural temperature gradient in Walker Branch, a spring-fed forested stream in eastern Tennessee, USA, to examine the influence of temperature on organic-matter decomposition. In this stream, upstream sites are warmer than downstream sites in winter and are cooler than downstream sites in summer. We used a cotton-strip assay to examine breakdown of a substrate of uniform quality (95% cellulose) along the temperature gradient monthly for 2 y. We also used litter bags to examine the interactive effects of leaf-litter quality (labile red maple [Acer rubrum] and tulip poplar [Liriodendron tulipifera] and less labile white oak [Quercus alba]), invertebrates, and temperature on breakdown rates along the downstream temperature gradient for 90 d in winter. Cotton-strip tensile loss and leaf-litter breakdown rates were highly variable. Tensile-loss rates probably were driven by a combination of daily and diel temperature, discharge, and streamwater nutrients that varied seasonally and spatially along the temperature gradient. Leaf-litter breakdown rates tended to be faster in warmer upstream sites (red maple = 0.0452/d, tulip poplar = 0.0376/d, white oak = 0.0142/d) and slower in cooler downstream sites (red maple = 0.0312/d, tulip poplar = 0.0236/d, white oak = 0.0107/d), and breakdown rates were positively correlated with total invertebrate density. Temperature sensitivity of decomposition was similar among the 3 litter types. These results highlight the high degree of spatial and temporal heterogeneity that can exist for ecosystem processes and their drivers. Quantifying this heterogeneity is important when scaling functional metrics to stream and watershed scales and for understanding how organic-matter processing will respond to the warmer stream-water temperatures expected as a result of global climate change.
Original language | English |
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Pages (from-to) | 518-533 |
Number of pages | 16 |
Journal | Freshwater Science |
Volume | 35 |
Issue number | 2 |
DOIs | |
State | Published - Jun 2016 |
Funding
We thank D. Brice, M. Burchi, K. McCracken, and J. Smith for technical assistance. Comments provided by J. Smith, W. Hill, J. Follstad-Shah, B. Taylor, anonymous referees, and Associate Editors B. McKie and E. Chauvet greatly improved earlier versions of this manuscript. This research was part of the long-term Walker Branch Watershed project and supported by the US Department of Energy's Office of Science, Biological and Environmental Research. Oak Ridge National Laboratory (ORNL) is managed by UT-Battelle, LLC, for the US Department of Energy under contract DE-AC05-00OR22725. NAG was partially supported through the ORNL Postdoctoral Research Associates Program administered by Oak Ridge Associated Universities, and SDT was supported by an Oakland University URC Faculty Research Fellowship Award.
Funders | Funder number |
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Oakland University URC | |
US Department of Energy | |
Office of Science | |
Biological and Environmental Research | |
Oak Ridge Associated Universities | |
Oak Ridge National Laboratory | DE-AC05-00OR22725 |
Keywords
- Cotton-strip assay
- Decay
- Diel temperature range
- Global change
- Litter quality
- Metabolic Theory of Ecology
- Nutrients
- Organic matter
- Q
- Shredders
- Snails
- Thermal gradient
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Dive into the research topics of 'Organic-matter decomposition along a temperature gradient in a forested headwater stream'. Together they form a unique fingerprint.Datasets
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Vegetation Inventory of Oak-Hickory Forest at Missouri Ozark (MOFLUX) Site: 2004-2017
Pallardy, S. (Creator), Gu, L. (Creator), Wood, J. D. (Creator), Hosman, K. P. (Creator) & Hook, L. A. (Creator), ORNLTESSFA (Oak Ridge National Lab's Terrestrial Ecosystem Science Scientific Focus Area (ORNL TES SFA)), Jan 1 2019
DOI: 10.25581/ornlsfa.016/1498529
Dataset
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Walker Branch Watershed: Effect of Dual Nitrogen and Phosphorus Additions on Nutrient Uptake and Saturation Kinetics, 2011-2012
Griffiths, N. (Creator) & Johnson, L. T. (Creator), ORNLTESSFA (Oak Ridge National Lab's Terrestrial Ecosystem Science Scientific Focus Area (ORNL TES SFA)), Jan 1 2018
DOI: 10.25581/ornlsfa.015/1484490
Dataset
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Walker Branch Watershed: Hourly, Daily, and Annual Precipitation
Mulholland, P. J. (Creator) & Griffiths, N. (Creator), ORNLTESSFA (Oak Ridge National Lab's Terrestrial Ecosystem Science Scientific Focus Area (ORNL TES SFA)), Jan 1 2016
DOI: 10.3334/CDIAC/ornlsfa.006
Dataset