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SUMMARY:Responses of soil bacterial and fungal communities to summer desic
 cation and rewetting in Mediterranean grasslands: summer precipitation pat
 tern matters
DTSTART:20140311T161500
DTEND:20140311T171500
DTSTAMP:20260924T233125Z
UID:7609fa4891a748b486dce0df908d8683bf85a29d1f2db91fa38a1c96
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Romain Barnard\, Groupe de recherche Agroecologie\, INRA Di
 jon\, FR\nAbstract:\nThe massive soil CO2 efflux associated with rewetting
  dry soils after the dry summer period significantly contributes to the an
 nual carbon budget of Mediterranean grasslands. Better understanding i) so
 il microbial adaptation strategies to a seasonally contrasted climate and 
 ii) the response of microorganisms to altered summer precipitation is impo
 rtant to predict future changes in carbon cycling in Mediterranean grassla
 nds. These two axes of research were tackled in both present (DNA-based) a
 nd potentially active (rRNA-based) soil bacterial and fungal communities\,
  by sequencing phylogenetic marker genes and quantifying the abundance of 
 these genes and transcripts.\nHow do soil microorganisms respond to extrem
 e desiccation and rewetting? In three California annual grasslands\, soil 
 microbial communities were tracked over a summer season\, and in response 
 to controlled rewetting of intact soil cores. Contrasting desiccation-rela
 ted bacterial life-strategies that were consistent across sites suggest th
 at predicted changes in precipitation patterns may affect soil nutrient an
 d carbon cycling by differentially impacting activity patterns of microbia
 l communities.\nHow do changes in summer precipitation pattern affect soil
  microbial response to fall wet-up? Intact soil cores were subjected to th
 ree different precipitation patterns over four months (full summer dry sea
 son\, extended wet season\, and absent summer dry season)\, then the effec
 ts of a controlled rewetting event on the soil CO2 efflux pulse and on soi
 l microbial communities were investigated. We found a strong\, significant
  positive relation between change in the structure of the potentially acti
 ve bacterial community and the magnitude of the CO2 pulse upon rewetting d
 ry soils. We suggest that the duration of severe dry conditions may be imp
 ortant in conditioning the response of the potentially active bacterial co
 mmunity to wet-up and in controlling the magnitude of the CO2 pulse result
 ing from wet-up events. Thus\, predicted changes in summer precipitation p
 attern may likely affect the metabolic potential of the soil bacterial com
 munity and the related magnitude of the rainfall-induced CO2 pulse upon re
 wetting.Short biography\nAs  a functional ecologist\, Romain Barnard inve
 stigates the response of terrestrial ecosystem functioning to global chang
 e. His research activities are directed towards better understanding the r
 esponses of soil C and N cycles in relation to plant physiology. After a P
 h.D. at Paris-Sud University on the effects of elevated CO2 on soil nitrog
 en cycling\, he worked at ETH Zürich for six years in Nina Buchmann’s l
 ab\, using stable isotopes to study the controls of time-lags between the 
 assimilation of carbon by the plant and its respiration by the soil. More 
 microbiological aspects of the effects of changes in precipitation pattern
 s on ecosystem functioning were later developed during a two-year stay at 
 University of California\, Berkeley in Mary Firestone’s lab. He is now a
  research scientist at the INRA (French National Institute for Agricultura
 l Research) in Dijon\, where he focuses on the effects of precipitation pa
 tterns on plant-soil interactions.
LOCATION:GR A3 32 http://plan.epfl.ch/?room=GR%20A3%2032
STATUS:CONFIRMED
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