- The study investigated how altering wetland hydrology through different flooding treatments (saturated, flashy flood, dry) affected denitrification rates, and whether the microbial source communities influenced rates. - Wetlands that naturally experience long floods had the highest denitrification rates after re-wetting. - Re-wetting and saturated treatments produced similar, higher denitrification rates than the dry treatment. - The hydrological treatment affected denitrification rates more than the origin of the microbial communities.

1. Background
• Climate change is predicted to cause periods of
drought followed by heavy rainfall, which will alter
flood regimes in wetlands.
• Flooding causes anaerobic conditions, which leads
microbial communities to perform denitrification.
NO3
- → N2
• Rewetting of the soil can also stimulate the nitrogen
cycle, and denitrification is stimulated by a floodpulse.
• Restored wetlands sometimes do not exhibit
expected denitrification rates. This could be due to
differences in their microbial communities.
Methods
Figure 1. Soil was collected from
each wetland in June. These
wetland source communities were
used to inoculate mesocosms of
sterile soil. Each mesocosm was
watered according to treatment:
saturated, flashy flood, and dry
(Figure 2).
Denitrification enzyme assays
were used to determine potential
denitrification rates.
Acknowledgements: We would like to thank the Kent Lab for the assistance in the field and lab.
Thanks are also extended to the Illinois Department of Transportation for the sampling sites. Funding was provided by NGRREC.
Objective
• To investigate if altering the hydrology can cause
wetland soil to produce differing denitrification rates in
a controlled setting.
• To see if different source communities produce
different denitrification rates.
Figure 1.
Blue: Flashy Floods
(016, 049, & 050)
GREEN: High Interannual Variability
(021, 029, & 035)
PINK: Long Floods
(017 & 046)
Microbial Community-specific Denitrification Response in Wetland
Following Flooding Event
Julia Antonson1, Dora Cohen2, Angela Kent1,2
, and Julie Zilles3
1Department of Natural Resources and Environmental Science, 2Program in Ecology, Evolution, and Conservation Biology, 3Civil and Environmental Engineering
University of Illinois at Urbana-Champaign
Results
Figure 2.
Flooding treatment.
Color groupings are based on the characteristic of the sites: blue sites have flashy floods, green sites have high interannual variability,
and pink sites have long floods.
• Re-wetting produced a pulse on Day 15 (Fig. 4).
• Wetlands with long floods had the highest rates of
denitrification after re-wetting (Fig 4).
• Overall denitrification rates were greatest in the
Saturated Treatment and lowest in the Dry
Treatment (ANOVA p=0.001501).
• Wetlands that are characterized by having long floods have higher rates of
potential denitrification following a re-wetting event.
• Re-wetting and saturated treatments gave similar potential denitrification
rates.
• The hydrological treatment affected rates of potential denitrification more
than the wetland microbial source communities.
Conclusion
Figure 3. Denitrification rates for Treatment 1: Saturated Mesocosms.
0
10
20
30
40
50
60
70
80
initial Day 1 Day 8 Day 15
Denitrification (ng N2O g-1hr-1)
Figure 4. Denitrification rates for Treatment 2: Re-wetted Mesocosms.
0
10
20
30
40
50
60
70
80
initial Day 1 Day 8 Day 15
Denitrification (ng N2O g-1hr-1)
Figure 5. Denitrification rates for Treatment 3: Dry Mesocosms.
0
10
20
30
40
50
60
70
80
initial Day 1 Day 8 Day 15
Denitrification (ng N2O g-1hr-1)
016
049
050
021
029
035
017
046
Saturated Saturated Drained Rewetted