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Warmer winters increase the rhizosphere carbon flow to mycorrhizal fungi more than to other microorganisms in a temperate grassland

Birgander, Johanna LU ; Rousk, Johannes LU and Olsson, Pål Axel LU (2017) In Global Change Biology 23(12). p.5372-5382
Abstract

A decisive set of steps in the terrestrial carbon (C) cycle is the fixation of atmospheric C by plants and the subsequent C-transfer to rhizosphere microorganisms. With climate change winters are expected to become milder in temperate ecosystems. Although the rate and pathways of rhizosphere C input to soil could be impacted by milder winters, the responses remain unknown. To address this knowledge-gap, a winter-warming experiment was established in a seminatural temperate grassland to follow the C flow from atmosphere, via the plants, to different groups of soil microorganisms. In situ 13CO2 pulse labelling was used to track C into signature fatty acids of microorganisms. The winter warming did not result in any... (More)

A decisive set of steps in the terrestrial carbon (C) cycle is the fixation of atmospheric C by plants and the subsequent C-transfer to rhizosphere microorganisms. With climate change winters are expected to become milder in temperate ecosystems. Although the rate and pathways of rhizosphere C input to soil could be impacted by milder winters, the responses remain unknown. To address this knowledge-gap, a winter-warming experiment was established in a seminatural temperate grassland to follow the C flow from atmosphere, via the plants, to different groups of soil microorganisms. In situ 13CO2 pulse labelling was used to track C into signature fatty acids of microorganisms. The winter warming did not result in any changes in biomass of any of the groups of microorganisms. However, the C flow from plants to arbuscular mycorrhizal (AM) fungi, increased substantially by winter warming. Saprotrophic fungi also received large amounts of plant-derived C—indicating a higher importance for the turnover of rhizosphere C than biomass estimates would suggest—still, this C flow was unaffected by winter warming. AM fungi was the only microbial group positively affected by winter warming—the group with the closest connection to plants. Winter warming resulted in higher plant productivity earlier in the season, and this aboveground change likely induced plant nutrient limitation in warmed plots, thus stimulating the plant dependence on, and C allocation to, belowground nutrient acquisition. The preferential C allocation to AM fungi was at the expense of C flow to other microbial groups, which were unaffected by warming. Our findings imply that warmer winters may shift rhizosphere C-fluxes to become more AM fungal-dominated. Surprisingly, the stimulated rhizosphere C flow was matched by increased microbial turnover, leading to no accumulation of soil microbial biomass.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
aboveground-belowground, arbuscular mycorrhizal fungi (AMF), climate change, NLFA, plant–soil interaction, PLFA, stable isotope, temperature
in
Global Change Biology
volume
23
issue
12
pages
11 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85034113516
  • wos:000414969000035
ISSN
1354-1013
DOI
10.1111/gcb.13803
language
English
LU publication?
yes
id
491fd675-08a6-4f4a-8b66-9c70581f7032
date added to LUP
2017-12-07 13:25:45
date last changed
2018-01-16 13:27:01
@article{491fd675-08a6-4f4a-8b66-9c70581f7032,
  abstract     = {<p>A decisive set of steps in the terrestrial carbon (C) cycle is the fixation of atmospheric C by plants and the subsequent C-transfer to rhizosphere microorganisms. With climate change winters are expected to become milder in temperate ecosystems. Although the rate and pathways of rhizosphere C input to soil could be impacted by milder winters, the responses remain unknown. To address this knowledge-gap, a winter-warming experiment was established in a seminatural temperate grassland to follow the C flow from atmosphere, via the plants, to different groups of soil microorganisms. In situ <sup>13</sup>CO<sub>2</sub> pulse labelling was used to track C into signature fatty acids of microorganisms. The winter warming did not result in any changes in biomass of any of the groups of microorganisms. However, the C flow from plants to arbuscular mycorrhizal (AM) fungi, increased substantially by winter warming. Saprotrophic fungi also received large amounts of plant-derived C—indicating a higher importance for the turnover of rhizosphere C than biomass estimates would suggest—still, this C flow was unaffected by winter warming. AM fungi was the only microbial group positively affected by winter warming—the group with the closest connection to plants. Winter warming resulted in higher plant productivity earlier in the season, and this aboveground change likely induced plant nutrient limitation in warmed plots, thus stimulating the plant dependence on, and C allocation to, belowground nutrient acquisition. The preferential C allocation to AM fungi was at the expense of C flow to other microbial groups, which were unaffected by warming. Our findings imply that warmer winters may shift rhizosphere C-fluxes to become more AM fungal-dominated. Surprisingly, the stimulated rhizosphere C flow was matched by increased microbial turnover, leading to no accumulation of soil microbial biomass.</p>},
  author       = {Birgander, Johanna and Rousk, Johannes and Olsson, Pål Axel},
  issn         = {1354-1013},
  keyword      = {aboveground-belowground,arbuscular mycorrhizal fungi (AMF),climate change,NLFA,plant–soil interaction,PLFA,stable isotope,temperature},
  language     = {eng},
  month        = {12},
  number       = {12},
  pages        = {5372--5382},
  publisher    = {Wiley-Blackwell},
  series       = {Global Change Biology},
  title        = {Warmer winters increase the rhizosphere carbon flow to mycorrhizal fungi more than to other microorganisms in a temperate grassland},
  url          = {http://dx.doi.org/10.1111/gcb.13803},
  volume       = {23},
  year         = {2017},
}