V encuentro servicios ecosistemas lemaire

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V encuentro servicios ecosistemas lemaire

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  • 1. Grasslands and ecosystem serviceswithin agro-ecosystemsNecessity for a multidisciplinary and multiscale approach Gilles LEMAIRE INRA, Lusignan France

2. New paradigms for grassland sciences- Ecosystem services, the benefits human societies andindividual peoples can obtain from ecosystemfunctioning: provisioning, regulating, cultural andsupporting-Trade-offs between grassland productivity forhuman food and fiber production and other services- Grasslands have to be analysed not only as a sourcefor feeding domestic herbivores, but also as a way forproduction ecosystem services. 3. Role and environmental impactsof grassland areasDirect effects: Soil protection (erosion, SOM, biology, structure...) Water quality (nitrate, phosphate, pesticides...) Air quality (CO2 sequestration, N2O ?, NH3 ?) Biodiversity (vegetation, soil fauna and flora, insects...)Interactions with management systems 4. Scientific Objectives Climate changesManagement practices HerbivoresGreenhouse gases Vegetation CO2 N2O Soil Organic Matter NOxC, N, P cyclesC sequestrationSoil biologySOM Biochemistry Water Quality NO3-Biodiversity DOC Pesticides... Vegetation Microorganisms Micro-Meso-fauna 5. Fonctions of SOMAgronomical impacts: Environnemental impacts: Soil properties Greenhouse gases : N2O, CO2 Soil Organic MatterCO2Soil fertility(SOM) sequestration Regulation of C, N, Pcycles Nitrate leaching 6. Inputs of fresh organic matterwithin grassland ecosystem Green litter Brown litter CO2DungInputSoil organic matter Chemical protection Labile SOM pool Physical protection Intermediate SOM pool Rhizodeposition Physicochemical protectionStable SOM pool DOC 7. Coupling C and N CyclesSoil organic matter represents 2/3rd of the total terrestrial carbon 8. 8060Net immobilisationC:Nratio 40 Net mineralisation20 0TimeDuring the decomposition of OM of residues there is adecline in C:N ratio through CO2 lossesand then a phaseof net immobilisation followed by a phase of netmineralisation of N depending on the C:N ratio ofresidues at origin. 9. Comparison of N fluxes between croping system and grasslandGross Min.Gross Imm.Net Min.4N (kg/ha/j)3210Annual crops GrasslandsAita (1996) Loiseau et Thiry (1992) 10. Leaf litters RootPlants C/N 30litters C/N 40-50 N mineral MOS Biomass- Under grassland, there is a constant supply of litters with high C:N- Then there is a high gross N immobilisation flux- In the same time plants have a more or less continuous Nabsorption rate all along the seasons- In consequence, NO3- cannot accumulate in soil > 3-5KgN.ha-1,except after high level application of N fertilizer, and under urinepatches- Then losses of N by nitrate leaching is very low even inwinterwhen stocking density remains not too high. 11. N leaching under grasslandsGrazing vs Cutting 300 Pture Grazing: Fauche 250High increase in Nleaching when > 200N lixivi (kg N /ha) 200kgN/ha 150 Cutting: 100 Low N leaching50 when < 400kgN/ha 0 0 200 Trade-off400 600Production vs Environment fertilisation (kg N efficace/ha) 12. Effect of stocking density on N leaching 160y = 8,77 e0,003x 140r=0.71 120 N lixivi (kg N/ha) 100806040Simon et al, 1997 ;Laurent et al.2000Verts et al, 200220Benoit et al., 1995 0 0 200 400 600800 10001200 chargement (UGB.JPE/ha) 13. CH4 N20 NOx NH3 CO2HerbivoresPhotosynthesis C-N-P Vegetation Soil NN absorption Feces OM UrineMineral N MIT MicrobesC-N coupling NitrateC-N decoupling 14. In grazing system C-N decoupling / C-N coupling depends onstocking densityC-N decoupling C-N couplingAbove a threshold stocking density C-N decoupling excessthe capacity of C-N recoupling of vegetation and soilmicrobes 15. Cutting system with indoor feeding and association withcropping system through use of straw and efficient compost production and recycling system could be highly intensified with reduced environmental impacts Hay-Silage Control of GHG Emission ?StrawRe-coupling C-NCompost 16. 1. Permanent vegetation and soil microbes couple strongly C-N cycles2. Grazing animals decouple C-N cycles and then provoke C and N emissions3. Intensification at grazing reaches a limit beyond which environmental fluxes become too important according to stocking density4. Cutting management is a way for a higher intensification of grasslandbut high cost!!!5. Decoupling C-N by animals indoor need to be acompanied by a re- coupling C-N within a coherent animal manure management6. Comparison between grazing and cutting must be done at whole system level and not only at field or paddock level 17. Role and environmental impacts of grassland areasIndirect effects on cropping systems:Control of weed communities and reduction of herbicide use;Control of pests and diseases and reduction of pesticide use;Recycling of nutrients and reduction of fertilizer use;Improved soil structure and reduction of fuel energy use;Heterogeneity of habitats and diversity of trophic chains; 18. Multi-function and multi-scale approachSpatial integrationLand use system mosacTerritoriesCatchmentLandscape Ecology and biodiversityInteractions between farms LandscapeFarmsProduction systemsConception-Evaluation of innovativesystems IngeneeringForage systemsEnvironnemental balanceSystemsMulti function evaluationCropping systemsBiogeochemical CyclesEnvironnemental Fluxes LocalBiodiversitProcessesExprimentation, MonitoringSoil-vegetationModelisation 19. Spatial interactions between grassland areas and cropping areas Flux of foodsGrasslands OMStocks mineralsLivestock Concentrates system ExportationsGrassland areaCroping area 20. Integration of grasslands withincropping systems Grassland Flux foodsOMPreceding mineralseffectStocks LivestockFollowing systemeffect GrasslandExportations Grains 21. Agro-Ecology IngeneeringFieldAnalyse of local processes and Environment xManagement interaction, What if ?Cropping systemConception and evaluation of cropping andforage systems, What is necessary for...?Forage systemConception and evaluation of livestock systemsfrom socio-economic and environment Livestock system perspectives 22. G. Paillard-INRAC. Maitre-INRA Interactions between cereal farms and livestock farms within a territory- Fluxes of organic matter and nutriments among specialised farmsand possibilities for more conservative biogeochemical fluxes bycoupling more strongly C and N- Diversification of land use and management systems through: - common crop rotation systems - exchanges of field - production and sell of hays 23. Contribution of Grasslands to Landscape EcologyFarmAtmosphereEnvironmentCrops GHG emissionClimateGrasslandsCO2 balance Soil LivestockTopographyBiodiversityLand useHabitat diversityTrophic networksCatchmentWater qualityFlux 24. Effects of grasslands on biodiversity at landscape level 25. The decline of biodiversitywithin European agriculture plains*Cultivated areas with high diversity of crops host the richest diversdity*>250 species of birds whose 173 prioritaries et 118 in danger From BirdLife 2004CNRS Chiz 26. During the last 30 years: decrease of livestock production decrease of grassland areas specialization for cereal production systems increase in field size reduction of the complexity of the landscape mosac 19581990 27. Effect of reintroduction of grasslands on LittleBustard population within a cereal cropping area CNRS Chiz 4,4clutch size 3,9 3,4 2,9 2,4 1,9 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008605040302010 0 95 96 97 989900010203 040506 0719191919 19 2020 20 2020 20 2020 28. Conclusions1- Grasslands through soil-vegetation interactions allow a strong C-N coupling leading to very conservative C and N cycles and reducedfluxes to atmosphere and hydrosphere.2- But grazing herbivores decouple greatly C and N, leading toincreasing emission of GHG and nitrate leaching with stockingdensity.3- Trade-off exists between grassland intensification andenvironment impacts.4- Grassland areas can contribute to mitigate environmental impactsof intensive cropping system at landscape and regional levels5- Mixed farming between arable crops and livestock productionsystems based on grasslands could help to reconcile high foodproduction systems with high level of ecosystem services 29. Necessity of structuring the scientificcommunity on continental ecosystem across EuropeScientific community on continental ecosystem is veryfragmented across a high variety of ecosystem types and a highvariety of scientific disciplines;Most of the environmental problems (water quality, air quality,soils quality, climatic changes, pollutant, biodiversity problems)require interdisciplinary approaches and long term observations,experimentations and data collection to enable simulation andforecasting the impacts of climate change and land use change oncontinental scale-ecology and to answer society questions.Answering environmental questions requires coupling more thansophisticating analysis of individual elementary processes. 30. , continueResearch infrastructures implementation in experimental ecology,is a prerequisite for structuring research on continentalecosystems, enabling understanding of ecosystem responses todisturbance, providing pertinent knowledge for managinganthropogenic ecosystems in a sustainable way.and then opportunities to merge European research projectswith South American ones within a wider international network? 31. Thank you for your attentionand for invitation