Global Change Effects on Grasslands and Feedbacks with Regard to Greenhouse Gas Fluxes
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Transcript of Global Change Effects on Grasslands and Feedbacks with Regard to Greenhouse Gas Fluxes
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Global Change Effects on Grasslands and Feedbacks with
Regard to Greenhouse Gas Fluxes
Klaus Butterbach-Bahl1, Xunhua Zheng2, Chunyan Liu2, Benjamin
Wolf1, Wei Wei Chen2, Xinguo Han3 and Nicolas Brüggemann1
1Institute for Meteorology and Climate Research, Garmisch-Partenkirchen, Germany2Institute for Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
3Institute of Botany, Chinese Academy of Sciences . Beijing, China
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Global importance of the biome type „grassland “
Boreal Forest17%
TemperateForest 8%
TemperateGrassland 13%
Savanna10%
TropicalRainforest 13%
Mountains6%
Desert19%
Scrub3%
Tundra11%
10.8%
17.8%
39%
32.4%
Forest
Grassland
Agro-ecosys.
Other
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Location of the target region
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Focus of MAGIM - I
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
IMGERS
MAGIM core sitesHydrologicalmeasuring points
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Climatic constraints
The climatic conditions limits NPP and make the steppe vulnerable to land use changes and grazing intensification
Precipitation [mm]
Mean 343.4
2003 371.3
2004 324.6
2005 166.1
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Grazing pressure and degradation
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Grazing
Soil properties
Plant production
Microbial turnover
Nutrient export
Species composition Biosphere/atmosphere
Site/regional hydrology
Erosion
Feed quantity and quality
„Sustainable“Management• Meat/wool• Biodiversity• Water• Erosion• Atmosphere• …….
Grazing effects
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Degradation process
1.5 sheep/ha9.0 sheep/ha
September 2006
Steppe degradation
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Gross N turnover rates: Significant differences between grazed and ungrazed sites
0.0
2.5
5.0
7.5
10.0
HGWG
UG99UG79
Ammonification Nitrification
Gro
ss N
tu
rno
ver
[µg
N g-1
SD
W d
ay-1
]
2005
June July August Sept. June July August Sept.0.0
2.5
5.0
7.5
Hol
st e
t al
., 2
008
, E
cosy
stem
sc
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Soil N2O-concentr.
N2O-flux
Soil T & moisture
Grazed versus non-grazed steppe systems: N2O
2007 2008
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Extremely highN2O-fluxes during freeze-thaw from ungrazed steppe
>70% of annual fluxes
Grazed versus non-grazed steppe systems: N2O
2007 2008
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Do natural steppe systems emit more N2O than grazed
systems?
0
2
4
6
8
10
12
14
-30
-20
-10
0
10
20
30
N2O
flu
x (N
2O-N
mg
m-2
h-1
) Daily air tem
peratu
re (°C)
1 1.5 2 2.5 30
25
50
75
Stocking rate [sheep ha -1]
N2O
-flu
x [g
N h
a-1
ve
ge
tatio
n p
eri
od
]
Upland steppe Riparian area Urine patches Sheepfold Dung heap
NO – On a regional scale nutrient management
overrides site scale effects
Holst et al., 2007, Plant and Soil
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Grazed versus non-grazed steppe systems: CH4
UG WG
Texture sL sL
pH 6.8±0.3 6.7±0.3
SOC [%] 2.5±0.6 2.6±0.5
Bulk dens.[g cm-3]
1.09±0.1 1.09±0.1
Gas Perm.-30kPa [cm d-1]
99.6±67 55.5±38
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Do natural steppe systems take up more CH4 than grazed
systems?
H1 H2 H3 H4 H5 H6 H7 H8
-60
-50
-40
-30
-20
-10
0
10
CH
4 flu
x (µ
g C
H4-C
m-2 h
-1)
-50--60 µg CH4-C m-2 h-1
≈2 kg C ha-1 growing season
x0.98 = -1.96 kg C ha-1
Sheep CH4 emissions10.8 -14.3 g CH4-C sheep day-1
≈ 2.2 kg C ha-1 growing season
X2 = 2.2 kg C ha-1
1.1 mg CH4-C m-2 h-1
≈ 70 kg C ha-1 growing season
X0.02 = 1.4 kg C ha-1
NO – CH 4 emission fro
m riparian areas and from sheep
are more important as CH 4 uptake by steppe soils
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K. Butterbach-Bahl | ERSEC International Conference| 05/05/09
KIT – die Kooperation vonForschungszentrum Karlsruhe GmbHund Universität Karlsruhe (TH)
Summary
• Grazing management has largely affected the biosphere atmosphere exchange of N2O:
• decreasing winter emissions• increase in N2O emissions from sheep folds
• as well as of CH4:
• Decreasing uptake of CH4
• Increasing emissions from sheep • Understanding of GHG fluxes on a regional scale
requires a detailed system analysis