Impact of varied precipitation and N deposition on grassland soil microbial communities and GHG flux

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Impact of varied precipitation and N deposition
on grassland soil microbial communities and GHG
flux

• Emma L. Aronson
• Allison lab
• UC Irvine
• May 17, 2012

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Precipitation hypotheses
Control
Increased Rainfall
Decreased Rainfall
Indicates rate of CO2 and N2O release, CH4
consumption
Indicates level of soil bacterial biodiversity
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N amendment hypotheses
Control
N Added
N
N
N
N
N
N
Indicates rate of CO2 and N2O release, CH4
consumption
Indicates level of soil bacterial biodiversity
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In March, N and H2O- increased CH4 uptake
production
uptake
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H2O- increased CH4 uptake
production
uptake
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N increased CH4 uptake
production
uptake
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Rain decreased, then increased uptake
production
uptake
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CH4 flux correlates with initial CH4
80 60 40 20 0 -20 -40 -60 -80
production
CH4 Flux (ppb min-1)
500 1000 1500 2000 2500 3000
3500
uptake
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H2O- decreased respiration
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Time interacts with precipitation
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Time interacts with precipitation
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Rainfall increases respiration
CO2 Flux
Precipitation
CO2 Flux (mg m-2 h-1)
Precipitation (in d-1)
Day of Study
Courtesy of Greg Winston
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N increases N2O release
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Time interacts with N treatment
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Time interacts with N treatment
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Rain Effect?
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Drought changed bacterial community
Significantly Different Phyla
Ambient Rainfall
Reduced Rainfall
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Reduced rainfall decreases variability in
microbial richness at OTU level
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Drought decreased respiration and variability in
bacterial diversity, increased CH4 uptake
Control
Increased Rainfall
Decreased Rainfall
Indicates rate of CO2 release, CH4 consumption
microbial community variability
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N amendment increased N2O release, CH4 uptake
N Added
Control
N
N
N
N
N
N
Indicates rate of N2O release, CH4 consumption
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Research in progress

• Further 16S 454 sequencing
• for all dates of gas analysis
• Shotgun metagenomic DNA sequencing
• GeoChip functional microarrays or qPCR
• Gene expression of soil N and C cycling functions

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Questions?