Bowen Ratio Energy Balance Measurement of Carbon Dioxide ...
CARBON BALANCE - uliege.be€¦ · 3 year carbon balance of the pasture including vertical (Eddy...
1
• F CO2 : Eddy covariance • F CH4-C : Based on dry matter intake • F manure : • F import : CARBON BALANCE OF A GRAZED PASTURE AND ITS RESPONSE TO GRAZING MANAGEMENT Elisabeth Jérôme (1) , Louis Gourlez de la Motte (1) , Yves Beckers (2) , Bernard Bodson (3) , Christine Moureaux (3) , Marc Aubinet (1) University of Liege, Gembloux Agro-Bio Tech, Belgium (1) Dept. of Biosystem Engineering, Ecosystems – Atmosphere Exchanges. (2) Dept AgroBioChem, Unit of crop science, Belgium (3) , Dept AgroBioChem, Unit of animal science. 0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30 0 5 10 15 20 Time of the day (hours) F CO2,night (μmol m -2 s -1 ) Confinement experiment II confinement (26.7 LU ha -1 ) after confinement 0 200 400 600 800 1000 1200 -30 -20 -10 0 10 20 PPFD (μmol m -2 s -1 ) F CO2,day (μmol m -2 s -1 ) Confinement experiment II confinement day (26.7 LU ha -1 ) before confinement 0 200 400 600 800 1000 1200 -30 -20 -10 0 10 20 PPFD (μmol m -2 s -1 ) F CO2,day (μmol m -2 s -1 ) Confinement experiment II confinement day (26.7 LU ha -1 ) after confinement Carbon budget of the pasture Jérôme et al. submitted to AFM • F harvest : C content .(m beforeharvest -m afterharvest ) • F leach : 7 ± 7gCm -2 y -1 (Schultze et al., 2009) • F product : C intake +F import +F CH4-C +C resp +C excretions Results Research Highlights Theory and methods NBP = F CO2 + F CH4-C + F manure + F import + F harvest + F product + F leach m× C content Direct and indirect grazing impact on C O2 fluxes Published : Jérôme et al. (AEE 194, 7-16, 2014) Study of direct impact by cattle confinement experiments Night F CO2 , larger during confinement than before or after. Day F CO2 , more positive (less negative) during confinement than before or after. On this basis, cattle respiration estimated to 2.59 ± 0.58 kg C LU −1 d −1 (8% of TER in at DTO) This pasture is about C neutral (behaves as a source on the two first years and as a sink on the third year). Management practices, sometimes dictated by climatic conditions, are the main factors influencing the pasture C balance. GPP max was significantly reduced with grazing intensity because of aboveground biomass reduction due to defoliation. R d10 was not significantly modified by grazing, probably because of conflicting processes. Confinement experiments allows cattle respiration estimation : it amounts to 2.59 ± 0.58 kg C LU −1 d −1 which represents 8% of TER. This research was funded by The « Direction Generale opérationnelle de l’Agriculture, des Ressources naturelles et de l’Environnement - Région Wallonne » Project n° D31-1278, January 2010 - December 2015 Contact Person: Gourlez de la Motte Louis - University of Liege – Gembloux Agro-Bio Tech (GxABT) – Department BIOSE – 2 Passage des Déportés – 5030 Gembloux – Belgium Tel : +32 (0)81 62 24 90 - Fax : +32 (0)81 62 24 39 e-mail : [email protected] C balance of a grassland grazed by cattle Nighttime CO 2 flux evolution during and after confinement A three year budget was implemented for a 4.2 ha pasture located in Wallonia (Dorinne Terrestrial Observatory, DTO) Mean NEE= +43±24 gCm -2 yr -1 Mean NBP=+7±26 gCm-2yr-1 The DTO site is C neutral Main driving variables : organic fertilization feed supplement climate (direct and indirect, through management) At daily and seasonal scale, grazing impact on CO 2 fluxes blurred by climate response Necessity to better highlight them 3 year carbon balance of the pasture including vertical (Eddy covariance) and horizontal (alternative techniques) fluxes. Data set covers 3 years from may 2010 to may 2013. • Cattle confinement (26 LU ha -1 ) during one day. • No cattle before and after confinement. • F CO2 comparison before, during and after confinement. • Investigation of the flux difference cattle respiration. Confinement zone is located in the main wind direction • Flux – PPFD regressions fit on 5-day periods. • GPP max and R d,10 decuced from regression. • Parameter difference (DGPP max , DR d,10 ) calculated between periods before and after a grazing period. • Analysis of relationship between DGPP max , DR d,10 and animal stocking rate during the grazing period. Flux – PPFD relation and related R d10 and GPP max parameters 0 50 100 150 200 250 -30 -20 -10 0 10 20 Average stocking rate (LU ha -1 day) D GPP max (μmol m -2 s -1 ) y = -0.08 x + 3.63 R² = 0.40 p-value = 0.004 0 50 100 150 200 250 -5 0 5 Average stocking rate (LU ha -1 day) D R d,10 (μmol m -2 s -1 ) y = -0.01 x + 0.10 R² = 0.07 p-value = 0.289 ΔGPP max is negatively correlated to stocking rate : defoliation by grazing affects pasture photosynthetic capacity. No significant correlation between DR d,10 and stocking rate : probably due to a combination of conflicting processes (autotrophic respiration decrease, heterotrophic respiration increase due to feaces, ….). Response of DGPP max and DR d10 to average stocking rate. One point corresponds to one grazing period (typically 10 – 30 days). Data set covers two years of measurements at DTO. Daytime F CO2 response to PPFD during and after (left) or before (right) confinement. Study of indirect impact by light curve response analysis Results Results
Transcript of CARBON BALANCE - uliege.be€¦ · 3 year carbon balance of the pasture including vertical (Eddy...
• FCO2: Eddy covariance • FCH4-C: Based on dry matter intake
• Fmanure: • Fimport:
CARBON BALANCE OF A GRAZED PASTURE AND ITS RESPONSE TO GRAZING MANAGEMENT
Elisabeth Jérôme(1), Louis Gourlez de la Motte(1), Yves Beckers(2), Bernard Bodson(3), Christine Moureaux(3), Marc Aubinet(1)
University of Liege, Gembloux Agro-Bio Tech, Belgium
(1) Dept. of Biosystem Engineering, Ecosystems – Atmosphere Exchanges. (2) Dept AgroBioChem, Unit of crop science, Belgium (3), Dept AgroBioChem, Unit of animal science.
0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:300
5
10
15
20
Time of the day (hours)
FC
O2,n
igh
t (µ
mo
l m
-2 s
-1)
Confinement experiment II
confinement (26.7 LU ha-1
)
after confinement
0 200 400 600 800 1000 1200-30
-20
-10
0
10
20
PPFD (µmol m-2
s-1
)
FC
O2,d
ay (
µm
ol
m-2
s-1
)
Confinement experiment II
confinement day (26.7 LU ha-1
)
before confinement
0 200 400 600 800 1000 1200-30
-20
-10
0
10
20
PPFD (µmol m-2
s-1
)
FC
O2,d
ay (
µm
ol
m-2
s-1
)
Confinement experiment II
confinement day (26.7 LU ha-1
)
after confinement
Carbon budget of the pasture Jérôme et al. submitted to AFM
• Fharvest: Ccontent.(mbeforeharvest-mafterharvest)
• Fleach: 7 ± 7gCm-2y-1 (Schultze et al., 2009) • Fproduct : Cintake+Fimport+FCH4-C+Cresp+Cexcretions
Results
Research Highlights
Theory and methods
NBP = FCO2 + FCH4-C + Fmanure + Fimport + Fharvest + Fproduct + Fleach
m× Ccontent
Direct and indirect grazing impact on CO2 fluxes Published : Jérôme et al. (AEE 194, 7-16, 2014)
Study of direct impact by cattle confinement experiments
Night FCO2, larger during confinement than before or after.
Day FCO2, more positive (less negative) during confinement than before or after.
On this basis, cattle respiration estimated to 2.59 ± 0.58 kg C LU−1d−1 (8% of TER in at DTO)
This pasture is about C neutral (behaves as a source on the two first years and as a sink on the third year).
Management practices, sometimes dictated by climatic conditions, are the main factors influencing the pasture C balance.
GPPmax was significantly reduced with grazing intensity because of aboveground biomass reduction due to defoliation.
Rd10 was not significantly modified by grazing, probably because of conflicting processes.
Confinement experiments allows cattle respiration estimation : it amounts to 2.59 ± 0.58 kg C LU−1d−1 which represents 8% of TER.
This research was funded by The « Direction Generale opérationnelle de l’Agriculture, des Ressources naturelles et de l’Environnement - Région Wallonne » Project n° D31-1278, January 2010 - December 2015
Contact Person: Gourlez de la Motte Louis - University of Liege – Gembloux Agro-Bio Tech (GxABT) – Department BIOSE – 2 Passage des Déportés – 5030 Gembloux – Belgium
Tel : +32 (0)81 62 24 90 - Fax : +32 (0)81 62 24 39 e-mail : [email protected]
C balance of a
grassland grazed
by cattle
Nighttime CO2 flux evolution during and after confinement
A three year budget was implemented for a 4.2 ha pasture located in Wallonia (Dorinne Terrestrial Observatory, DTO)
Mean NEE= +43±24 gCm-2yr-1
Mean NBP=+7±26 gCm-2yr-1
The DTO site is C neutral
Main driving variables :
organic fertilization feed supplement climate (direct and indirect, through management)
At daily and seasonal scale,
grazing impact on CO2 fluxes blurred by climate response
Necessity to better highlight them
3 year carbon balance of the pasture including vertical (Eddy covariance) and horizontal
(alternative techniques) fluxes. Data set covers 3 years from may 2010 to may 2013.
• Cattle confinement (26 LU ha-1) during one day.
• No cattle before and after confinement. • FCO2 comparison before, during and after
confinement. • Investigation of the flux difference cattle respiration.
Confinement zone is located in the main wind direction
• Flux – PPFD regressions fit on 5-day periods.
• GPPmax and Rd,10 decuced from regression.
• Parameter difference (DGPPmax , DRd,10) calculated between periods before and after a grazing period.
• Analysis of relationship between DGPPmax , DRd,10 and animal stocking rate during the grazing period.
Flux – PPFD relation and related Rd10 and GPPmax parameters
0 50 100 150 200 250-30
-20
-10
0
10
20
Average stocking rate (LU ha-1
day)
DG
PP
max (
µm
ol
m-2
s-1
) y = -0.08 x + 3.63
R² = 0.40
p-value = 0.004
0 50 100 150 200 250-5
0
5
Average stocking rate (LU ha-1
day)
DR
d,1
0 (
µm
ol
m-2
s-1
) y = -0.01 x + 0.10
R² = 0.07
p-value = 0.289
ΔGPPmax is negatively correlated to stocking rate : defoliation by grazing affects pasture photosynthetic capacity.
No significant correlation between DRd,10 and stocking rate : probably due to a combination of conflicting processes (autotrophic respiration decrease, heterotrophic respiration increase due to feaces, ….).
Response of DGPPmax and DRd10 to average stocking rate. One point corresponds to one grazing period (typically 10 – 30 days). Data set covers two years of measurements at DTO.
Daytime FCO2 response to PPFD during and after (left) or before (right) confinement.
Study of indirect impact by light curve response analysis
Results
Results
