Modeling the Greenhouse gases of cropland/grassland
At European scale
N. Viovy, S. Gervois, N. Vuichard, N. de Noblet-Ducoudré, B. Seguin, N. Brisson,
J.F. Soussana , P. Ciais
Aim of modeling: Simulate the GHG exchanges in response to
Environmental conditions (climate and management) based on
parameterization of biological processes of plant functioning
Advantage:
• can be spatially explicit
• can be used to extrapolate to the future
• can be used to test several scenarios of climate evolution,
mitigation option etc….
State of art of modeling of greenhouse gases in ecosystems
Large scale process models : (eg. LPJ, ORCHIDEE…)
Can be run at european scale but crude description of processes
Especially for agriculture (Mainly designed for natural vegetation, forest)
Local process models (eg. Crops: STICS, grassland PASIM)
Good description of processes and take into account for management
But only at field level.
Integrated model: (eg. Fasset)
Integrate antropogenic dimention at fram level with simplified
Ecosystems processes
How to combine these approaches to assess european scale GHG budget
On agricultural lands
Two possible approaches:
Coupling Large scale models with local scale models
Improve existing processes in large scale models for better
Representation of crops and taking into account for management
Coupling ORCHIDEE with STICS and PASIM
ORCHIDEE:
Global scale model representing 12 « plant functionnal types »
Simulate both biophysical and biogeochemical processes for net
Exchange with the atmosphere
Part of the IPSL climate model.
STICS:
Generic crop model designed for main crops type. Prediction of
Crop yield. Take into account for fertilization, irrigation,
PASIM:
Designed to represent pasture. Include both cutting and grazing by
Ruminants and there effects on the GHC balance
(including N2O and CH4)
Stategy of coupling
PASIM
/STICS
ORCHIDEE
Coupling
In situ forcing
Comparison with in-situ data
Climate forcing (ATEAM)
Vegetation map (CORINE)
« optimum management »
European statistics
e.g –fertilizers input,cutting/
grazing systems stocking rate,
irrigation
European scale
hybrid model
CO2,CH4,N2O budget
on grasslands and crops
Mitigation options
Data available at european Level
Climate data: Climate data from ATEAM european project (EVK2-2000-00075)
Combination of 10’x10’ climatology with 0.5°x0.5° CRU climate
Data to construct a « pseudo 10’x10’ » data set for all the 20th century
Land cover: CORINE land cover map
Very high resolution and quality data set (but no information on crops
types)
Soil: European soil map (problem of access to the data)
The main problem is to obtain regional statistics on management
Practices !
Cropland: Coupling STICS and ORCHIDEE
e.g : LAI is calculated by STICS, photosynthesis by ORCHIDEE
Improvement of the hybrid model:
Wheat
Corn
Aerial biomass (gC / m2)
Aerial biomass (gC / m2)
1500
1500
1000
1000
500
500
0
50
100 150 200 250 300 350
days
ORCHIDEE-STICS
STICS (an agronomy model)
0
50
100 150 200 250 300 350
days
Measurements
‘validation’ site: Corn at Bondville (Illinois, US)
net carbon flux (gC/m2/day)
5
evapotranspiration (mm/day)
8
7
0
6
5
-5
4
3
-10
2
1
-15
50
100 150 200 250 300 350
days
sowing
rain
deficit
0
50
harvest
100 150 200 250 300 350
days
sowing
rain
harvest
deficit
‘validation’ site: wheat at Ponca (Oklahoma, US)
net carbon flux (gC/m2/day)
-5
-10
50
7
6
5
4
3
2
1
100 150 200 250 300 350
Days
Rain deficit
harvest
Measurements problem
0
-15
evapotranspiration (mm/day)
8
Measurements problem
5
sowing
rising
0
50
100 150 200 250 300 350
Days
Rain deficit
harvest
sowing
rising
Comparison of LAI between ORCHIDEE, ORCHIDEE – STICS and MODIS
January ORCHIDEE – STICS
January ORCHIDEE
January MODIS (Myneni et al.)
July ORCHIDEE - STICS
July ORCHIDEE
July MODIS (Myneni et al.)
Time evolution of simulated GPP and NEP (averaged over Europe)
9
GPP
(gC/m2/day)
ORCHIDEE
ORCHIDEE-STICS
4
 Very stong increase in seasonal
cycle
-5
NEP
(gC/m2/day)
Simulation for the 20th century:
impact of CO2, climate and management
Atmospheric CO2 (ppm)
400
367.9
350
Atmospheric CO2
300
297
250
1900
1920
1940
1960
1980
2000
Mean annual temperature (°C)
Annual rainfall (mm)
Climate
Species change
Management
Organic fertilizer
1900
1920
1940
1960
1980
2000
Difference of production 2000-1900
CO2
CO2 + climate + management
CO2 + climate
Evolution of production (tC/ha/y)
Wheat annual NPP
Wheat yield (from FAO)
12
8
NPP ( tC / ha/y)
8.02
6
4
2
1.28
0
1900
1920
1940
1960
1980
11.01
11
10.03
10
9
8
7.46
7
6
1920
1940
1960
1980
CO2
CO2 + climate
CO2 + climate + management
Grassland: coupling PASIM and ORCHIDEE
Same forcing as for cropland (climatologic run)
Two scenarios:
• cutting
• grazing: automatic determination of stocking rate
Cutting scenario
Yield (tC/(ha year))
NPP (tC/ha/y)
N2O (Kg N/ha/y)
Total GH effect (tC/ha/y)
Grazing scenario
Stocking rate (LU/ha/y)
NPP (tC/ha/y)
N2O (Kg N/ha/y)
CH4 (t/ha/y)
Total GH effect (tC/ha/y)
Conclusions and perspectives
The development of the hybrid