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Title: Soil respiration and bacterial structure and function after 17 years of a reciprocal soil transplant experiment

The effects of climate change on soil organic matter—its structure, microbial community, carbon storage, and respiration response—remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5 °C monthly maximum air temperature, +50 mm yr-1precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplantsmore » did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. Lastly, these results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and longer-term soil microbial dynamics may be significantly different under changing climate.« less
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [2]
  1. Pacific Northwest National Lab. (PNNL), College Park, MD (United States). Joint Global Change Research Institute
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Washington State Univ., Pullman, WA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1932-6203; KP1702010
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 11; Journal Issue: 3; Journal ID: ISSN 1932-6203
Public Library of Science
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES climate change; soil organic matter; physical geography; climate change; soil respiration; Q10 temperature coefficient; rattlesnakes; bacteria; carbon dioxide; community structure