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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
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• 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.

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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
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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
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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)
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Stategy of coupling
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Data available at european Level
Climate data Climate data from ATEAM european
project (EVK2-2000-00075) Combination of 10x10
climatology with 0.5x0.5 CRU climate Data to
construct a  pseudo 10x10  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 !

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Cropland Coupling STICS and ORCHIDEE
e.g LAI is calculated by STICS, photosynthesis
by ORCHIDEE
Improvement of the hybrid model
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(No Transcript)
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Comparison of LAI between ORCHIDEE, ORCHIDEE
STICS and MODIS
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Time evolution of simulated GPP and NEP (averaged
over Europe)
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NEP (gC/m2/day)
? Very stong increase in seasonal cycle
-5
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Simulation for the 20th century impact of CO2,
climate and management
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Difference of production 2000-1900
CO2 climate management
CO2
CO2 climate
Evolution of production (tC/ha/y)
Wheat annual NPP
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11.01
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10.03
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NPP ( tC / ha/y)
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7.46
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1920
1940
1960
1980
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Grassland coupling PASIM and ORCHIDEE
Same forcing as for cropland (climatologic run)

• Two scenarios
• cutting
• grazing automatic determination of stocking
  rate

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Cutting scenario
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Grazing scenario
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Conclusions and perspectives
The development of the hybrid