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 CO2,CH4,N2O budget on grasslands and crops Mitigation options European statistics e.g –fertilizers input,cutting/ grazing systems stocking rate, irrigation ORCHIDEE Climate forcing (ATEAM) Vegetation map (CORINE) PASIM /STICS In situ forcing Coupling European scale hybrid model Comparison with in-situ data « optimum management »

Data available at european Level Climate data: Climate data from ATEAM european project (EVK ) Combination of 10’x10’ climatology with 0.5°x0.5° CRU climate Data to construct a « pseudo 10’x10’ » data set for all the 20 th 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 Improvement of the hybrid model: e.g : LAI is calculated by STICS, photosynthesis by ORCHIDEE

‘validation’ site: Corn at Bondville (Illinois, US) ‘validation’ site: wheat at Ponca (Oklahoma, US)

January ORCHIDEE – STICS January ORCHIDEE January MODIS (Myneni et al.) July ORCHIDEE July MODIS (Myneni et al.) July ORCHIDEE - STICS Comparison of LAI between ORCHIDEE, ORCHIDEE – STICS and MODIS

GPP (gC/m2/day) Time evolution of simulated GPP and NEP (averaged over Europe) ORCHIDEE ORCHIDEE-STICS  Very stong increase in seasonal cycle NEP (gC/m2/day)

Simulation for the 20 th century: impact of CO2, climate and management Atmospheric CO2 (ppm) Atmospheric CO2 Mean annual temperature (°C)Annual rainfall (mm) Climate Organic fertilizer Inorganic fertilizer + irrigation Species change Management

Wheat annual NPP NPP ( tC / ha/y) CO2 CO2 + climate CO2 + climate + management CO2 CO2 + climate CO2 + climate + management Evolution of production (tC/ha/y) Difference of production

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)) Total GH effect (tC/ha/y) NPP (tC/ha/y) N2O (Kg N/ha/y)

Stocking rate (LU/ha/y) NPP (tC/ha/y) N2O (Kg N/ha/y) CH4 (t/ha/y) Total GH effect (tC/ha/y) Grazing scenario

Conclusions and perspectives The development of the hybrid