A decade of free‐air CO2 enrichment increased the carbon throughput in a grass‐clover ecosystem but did not drastically change carbon allocation patterns. (24th October 2013)

• Record Type: Journal Article
• Authors: Staddon, Philip L.; Reinsch, Sabine; Olsson, Pål A.; Ambus, Per; Lüscher, Andreas; Jakobsen, Iver; Briones, Maria Jesus
• Is Part Of: Functional ecology. Volume 28:Number 2(2014:Apr.)
• Page Start: 538
• Page End: 545
• Publication Date: 2013-10-24
• Subjects: Ecology -- Periodicals; 574.505
• DOI: 10.1111/1365-2435.12183
• Languages: English
• ISSNs: 0269-8463

Abstract

<abstract abstract-type="main" id="fec12183-abs-0001"> <title>Summary</title> <p> <list id="fec12183-list-0001" list-type="order"> <list-item> <p>The response of the soil carbon cycle to increasing atmospheric CO<sub>2</sub> concentration has far reaching consequences for the ecosystem carbon balance under future climatic conditions. We report on work carried out in the Swiss free‐air CO<sub>2</sub> enrichment (FACE) experiment, where we used <italic>in situ</italic><sup>13</sup>CO<sub>2</sub> labelling to determine whether elevated CO<sub>2</sub> (+230 μL L<sup>−1</sup>) concentration changes the fate of recently assimilated carbon in the soil microbial community.</p> </list-item> <list-item> <p>Elevated CO<sub>2</sub> (eCO<sub>2</sub>) concentration had an overall positive effect on microbial abundance (<italic>P </italic><<italic> </italic>0·001) with the gram‐negative bacteria showing significantly increased quantities.</p> </list-item> <list-item> <p>Gram‐negative bacteria and saprotrophic fungi tended to utilize a higher amount of recently assimilated carbon under eCO<sub>2</sub>. Arbuscular mycorrhizal fungi (AMF) utilized plant‐assimilated carbon within 1 day after the <sup>13</sup>CO<sub>2</sub> pulse and <sup>13</sup>C uptake patterns in AMF suggest that carbon transfer is faster under eCO<sub>2</sub> concentration than under ambient CO<sub>2</sub> (aCO<sub>2</sub>). Additionally, the respiration of recently assimilated carbon was significantly higher under eCO<sub>2</sub> than aCO<sub>2</sub> concentration.</p> </list-item> <list-item> <p>Our data suggest that elevated atmospheric CO<sub>2</sub> concentration accelerated and increased the utilization of recently assimilated carbon by the microbial community without changing the microbial community composition drastically.</p> </list-item> <list-item> <p>We conclude that a higher standing soil microbial biomass under eCO<sub>2</sub> concentration was the key cause for the higher carbon flow through the plant–soil system. Carbon utilization by microbial functional groups was only little affected by a decade of CO<sub>2</sub> enrichment.</p> </list-item> </list> </p> </abstract>