-
The Netherlands
Greenhouse gas emissions from wetlands with different vegetation type
Jeroen de Klein1, Frits Gillissen1, Chih-Chung Wu1, Irene Paredes Losada2, Annelies Veraart31Aquatic Ecology and Water quality management group Wageningen University, Wageningen, The Netherlands 2Estación Biológica de Doñana, Sevilla, Spain 3Radboud University, Nijmegen, The Netherlands
-
The Netherlands
Area of free-floating plants on wetlands is increasing effect on fluxes of CO2 and CH4
Eichornia cover BrasilAzolla cover Doñana Spain
Introduction
-
The Netherlands
Introduction
(Contrasting) mechanisms of floating plants on GHG emission
• Oxygen depletion under floating vegetation: Anoxic decomposition; more CH4
• Temperature increase lower oxygen (decomposition more enhanced than production)
• However, with floating plants less exchange with atmosphere entrapment and oxidation of CH4 bubbles in rootzone
Veraart at al. 2010 Biogeochemistry
-
The Netherlands
Air/Water gas exchange rate
• Effect of floating biomass on air/water gas exchange rate• Effect of floating biomass on CH4-ebulition • 3 free-floating species (Azolla, Salvinia, Eichhornia)
-
The Netherlands
Gas exchange rate K Eichhornia
Azolla
Air/Water gas exchange rateFr
actio
n of
Ope
n W
ater
K (
-)
-
The Netherlands
Micro-cosms experiments
• Microcosms (submerged, floating (Azolla, Lemna), controls, n=4)• Temperature range 10-25 °C (measured in light and dark; 12/12h)• Gasfluxes measured with Innova TGA
-
The Netherlands
Results CH4 fluxes cosm-experiments
Accelerated effect of temperature on DOVeraart A.J. and de Klein J.J.M. (2011), PLoS ONE, 6(3), 2-7
Temperature experiment
-0.01
0
0.01
0.02
0.03
0.04
10 15 20 25
Gas
flux
(mm
ol m
-2h-
1 )
Temperature °c
CH4 subm
Dark
Light
CH4 submerged plants
-0.01
0
0.01
0.02
0.03
0.04
10 15 20 25
Gas
flux
(mm
ol m
-2h-
1 )
Temperature °c
CH4 floatCH4 floating vegetation
-
The Netherlands
0
2
4
6
8
10
12
14
16
18
-4
-3
-2
-1
0
1
2
3
4
5
6
Lemna Azolla Elodea No Plants
Diss
olve
d O
xyge
n (m
g/l)
Prod
uctio
n (m
mol
m- ²
hr-1
)
CO2darklightDO DarkDO Light
Results gas fluxes cosm-experiments
continuous experiment (average fluxes 13 weeks, 20-25°C)
-
The Netherlands
Results gas fluxes cosm-experiments
continuous experiment (average fluxes 13 weeks, 20-25°C)
0
2
4
6
8
10
12
14
16
18
0
0.05
0.1
0.15
0.2
0.25
Lemna Azolla Elodea No Plants
Diss
olve
d O
xyge
n (m
g/l)
Prod
uctio
n (m
mol
m- ²
hr-1
)
CH4darklightDO DarkDO Light
-
The Netherlands
• 9 shallow lakes and ponds in marshland (single measurement, 6 experiments per lake)• Different cover of submerged and floating vegetation• Gas fluxes measured with floating chamber (Innova and LGR)
Field measurements Doñana Wetlands
-
The Netherlands
-1.0
-0.5
0.0
0.5
1.0
1.5
low medium abundant
gas f
lux
(mm
ol m
-2h-
1 )
CO2
0.0
0.1
0.2
0.3
low medium abundant
CH4
Average gas fluxes (daytime) related to macrophytes density
Field measurements Doñana Wetlands
-
The Netherlands
To summarize
GHG fluxes from microcosms and shallow vegetated lakes
- Clear temperature effect on CH4 with floating plants (temperature
threshold ?)
- With increasing floater dominance: shift from carbon sink to source
- In field conditions: highest CH4 emissions with median vegetation cover
- DO depletion effect of floaters seem to prevail above gas exchange
limitation
- However, overall effect is variable (species, temperature, local
conditions)
CO2CH4
GHG potential
-
The Netherlands
Greenhouse gas emissions from wetlands with different vegetation typeSlide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13