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Title: Changes in substrate availability drive carbon cycle response to chronic warming

Abstract

As earth's climate continues to warm, it is important to understand how the capacity of terrestrial ecosystems to retain carbon (C) will be affected. We combined measurements of microbial activity with the concentration, quality, and physical accessibility of soil carbon to microorganisms to evaluate the mechanisms by which more than two decades of experimental warming has altered the carbon cycle in a Northeast US temperate deciduous forest. We have found that concentrations of soil organic matter were reduced in both the organic and mineral soil horizons. The molecular composition of the carbon was altered in the mineral soil with significant reductions in the relative abundance of polysaccharides and lignin, and an increase in lipids. Mineral-associated organic matter was preferentially depleted by warming in the top 3 cm of mineral soil. We found that potential extracellular enzyme activity per gram of soil at a common temperature was generally unaffected by warming treatment. However, by measuring potential extracellular enzyme activities between 4 and 30 °C, we found that activity per unit microbial biomass at in-situ temperatures was increased by warming. This was associated with a tendency for microbial biomass to decrease with warming. These results indicate that chronic warming has reduced soilmore » organic matter concentrations, selecting for a smaller but more active microbial community increasingly dependent on mineral-associated organic matter.« less

Authors:
ORCiD logo [1];  [2];  [3];  [4]
  1. Univ. of Massachusetts, Amherst, MA (United States). Graduate Program in Organismic and Evolutionary Biology
  2. Univ. of New Hampshire, Durham, NH (United States). Dept. of Natural Resources and the Environment
  3. The Marine Biological Lab., Woods Hole, MA (United States). The Ecosystems Center
  4. Univ. of Massachusetts, Amherst, MA (United States). Dept. of Microbiology
Publication Date:
Research Org.:
The Marine Biological Lab., Woods Hole, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23). Climate and Environmental Sciences Division; Univ. of Massachusetts, Amherst, MA (United States); National Science Foundation (NSF)
OSTI Identifier:
1376980
Alternate Identifier(s):
OSTI ID: 1424964
Grant/Contract Number:
SC0010740; 1237491; G20141015649466
Resource Type:
Journal Article: Published Article
Journal Name:
Soil Biology and Biochemistry
Additional Journal Information:
Journal Volume: 110; Journal Issue: C; Journal ID: ISSN 0038-0717
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Soil carbon; Climate feedbacks; Enzyme activity; Microbial adaptation

Citation Formats

Pold, Grace, Grandy, A. Stuart, Melillo, Jerry M., and DeAngelis, Kristen M. Changes in substrate availability drive carbon cycle response to chronic warming. United States: N. p., 2017. Web. doi:10.1016/j.soilbio.2017.03.002.
Pold, Grace, Grandy, A. Stuart, Melillo, Jerry M., & DeAngelis, Kristen M. Changes in substrate availability drive carbon cycle response to chronic warming. United States. doi:10.1016/j.soilbio.2017.03.002.
Pold, Grace, Grandy, A. Stuart, Melillo, Jerry M., and DeAngelis, Kristen M. Wed . "Changes in substrate availability drive carbon cycle response to chronic warming". United States. doi:10.1016/j.soilbio.2017.03.002.
@article{osti_1376980,
title = {Changes in substrate availability drive carbon cycle response to chronic warming},
author = {Pold, Grace and Grandy, A. Stuart and Melillo, Jerry M. and DeAngelis, Kristen M.},
abstractNote = {As earth's climate continues to warm, it is important to understand how the capacity of terrestrial ecosystems to retain carbon (C) will be affected. We combined measurements of microbial activity with the concentration, quality, and physical accessibility of soil carbon to microorganisms to evaluate the mechanisms by which more than two decades of experimental warming has altered the carbon cycle in a Northeast US temperate deciduous forest. We have found that concentrations of soil organic matter were reduced in both the organic and mineral soil horizons. The molecular composition of the carbon was altered in the mineral soil with significant reductions in the relative abundance of polysaccharides and lignin, and an increase in lipids. Mineral-associated organic matter was preferentially depleted by warming in the top 3 cm of mineral soil. We found that potential extracellular enzyme activity per gram of soil at a common temperature was generally unaffected by warming treatment. However, by measuring potential extracellular enzyme activities between 4 and 30 °C, we found that activity per unit microbial biomass at in-situ temperatures was increased by warming. This was associated with a tendency for microbial biomass to decrease with warming. These results indicate that chronic warming has reduced soil organic matter concentrations, selecting for a smaller but more active microbial community increasingly dependent on mineral-associated organic matter.},
doi = {10.1016/j.soilbio.2017.03.002},
journal = {Soil Biology and Biochemistry},
number = C,
volume = 110,
place = {United States},
year = {Wed Mar 22 00:00:00 EDT 2017},
month = {Wed Mar 22 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.soilbio.2017.03.002

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

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  • As earth's climate continues to warm, it is important to understand how the capacity of terrestrial ecosystems to retain carbon (C) will be affected. We combined measurements of microbial activity with the concentration, quality, and physical accessibility of soil carbon to microorganisms to evaluate the mechanisms by which more than two decades of experimental warming has altered the carbon cycle in a Northeast US temperate deciduous forest. We have found that concentrations of soil organic matter were reduced in both the organic and mineral soil horizons. The molecular composition of the carbon was altered in the mineral soil with significantmore » reductions in the relative abundance of polysaccharides and lignin, and an increase in lipids. Mineral-associated organic matter was preferentially depleted by warming in the top 3 cm of mineral soil. We found that potential extracellular enzyme activity per gram of soil at a common temperature was generally unaffected by warming treatment. However, by measuring potential extracellular enzyme activities between 4 and 30 °C, we found that activity per unit microbial biomass at in-situ temperatures was increased by warming. This was associated with a tendency for microbial biomass to decrease with warming. These results indicate that chronic warming has reduced soil organic matter concentrations, selecting for a smaller but more active microbial community increasingly dependent on mineral-associated organic matter.« less
  • High altitude alpine meadows are experiencing considerably greater than average increases in soil surface temperature, potentially as a result of ongoing climate change. The effects of warming on plant productivity and soil edaphic variables have been established previously, but the influence of warming on soil microbial community structure has not been well characterized. Here, the impact of 15 months of soil warming (both + 1 and + 2 degrees C) on bacterial community structure was examined in a field experiment on a Tibetan plateau alpine meadow using bar-coded pyrosequencing. Warming significantly changed (P < 0.05) the structure of the soilmore » bacterial community, but the alpha diversity was not dramatically affected. Changes in the abundance of the Actinobacteria and Alphaproteobacteria were found to contribute the most to differences between ambient (AT) and artificially warmed conditions. A variance partitioning analysis (VPA) showed that warming directly explained 7.15% variation in bacterial community structure, while warming-induced changes in soil edaphic and plant phenotypic properties indirectly accounted for 28.3% and 20.6% of the community variance, respectively. Interestingly, certain taxa showed an inconsistent response to the two warming treatments, for example Deltaproteobacteria showed a decreased relative abundance at + 1 degrees C, but a return to AT control relative abundance at + 2 degrees C. This suggests complex microbial dynamics that could result from conditional dependencies between bacterial taxa.« less
  • The availability of sorbed substrate for microbial degradation on granular activated carbon was investigated in comparative studies of substrate utilization and biological growth in fluidized-bed batch-recycle reactors containing GAC, coal and sand. The substrates used were o-cresol, acetophenone, phenol and benzoic acid. These differed greatly in adsorbability. The specific microbial growth rates were found to be the same on the two non-adsorbing media. However, an enhanced biodegradation rate and a higher specific growth rate was measured on GAC. Then on the non-adsorbing media. This enhanced growth rate is a function of substrate availability. Experiments showed that an increase in sorbedmore » substrate concentrations and a decrease in particle diameter increased the specific growth rate. A maximum enhanced rate is approached for each particle size as sorbed substrate increases.« less
  • The timing of phenological events exerts a strong control over ecosystem function and leads to multiple feedbacks to the climate system1. Phenology is inherently sensitive to temperature (though the exact sensitivity is disputed2) and recent warming is reported to have led to earlier spring, later autumn3,4 and increased vegetation activity5,6. Such greening could be expected to enhance ecosystem carbon uptake7,8, though reports also suggest decreased uptake for boreal forests4,9. Here we assess changes in phenology of temperate forests over the eastern US during the past two decades, and quantify the resulting changes in forest carbon storage. We combine long-term groundmore » observations of phenology, satellite indices, and ecosystem-scale carbon dioxide flux measurements, along with 18 terrestrial biosphere models. We observe a strong trend of earlier spring and later autumn. In contrast to previous suggestions4,9 we show that carbon uptake through photosynthesis increased considerably more than carbon release through respiration for both an earlier spring and later autumn. The terrestrial biosphere models tested misrepresent the temperature sensitivity of phenology, and thus the effect on carbon uptake. Our analysis of the temperature-phenology-carbon coupling suggests a current and possible future enhancement of forest carbon uptake due to changes in phenology. This constitutes a negative feedback to climate change, and is serving to slow the rate of warming.« less
  • The increase in carbon dioxide in the atmosphere is expected to cause a warming of the earth. This increase is due to the fact that more carbon is released into the atmosphere than is removed by the biota and the oceans. Understanding the carbon cycle is important in predicting future warming. A major uncertainty is the timing and magnitude of future releases of CO/sub 2/ from the burning of fossil fuels. Today, 1.1 tons of carbon as CO/sub 2/ are released every year for every person on Earth. Estimates are given on how much CO/sub 2/ has been released intomore » the atmosphere since fossil fuels have been burned. The ultimate aim of carbon cycle research is to predict how the concentration of CO/sub 2/ in the atmosphere will vary as mankind pumps more and more of it into the atmosphere.« less