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

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
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:
Grant/Contract Number:
SC0010740; 1237491; G20141015649466
Published Article
Journal Name:
Soil Biology and Biochemistry
Additional Journal Information:
Journal Volume: 110; Journal Issue: C; Journal ID: ISSN 0038-0717
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)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; Soil carbon; Climate feedbacks; Enzyme activity; Microbial adaptation
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1424964