Downscaled impacts of climate change on the harmfulness of weeds in field crops in mainland France

Started in september 2023

Supervisors: Thierry Castel (MC HDR directeur, BGS – CRC) ; Nathalie Colbach (DR HDR co-directrice, INRAE – UMR Agroécologie, pole gestion des adventices) ; Delphine Moreau (DR HDR co-encadrante, INRAE – UMR Agroécologie, pole gestion des adventices)

Funding: FCPR grant (‘formation complémentaire par la recherche’) of the French ministry of agriculture and food

Abstract

By altering environmental conditions, climate change questions the sustainability of cropping systems and strategies for the agroecological transition. Because of rising temperatures, shifts in the water cycle and reduced use of herbicides, cropping systems need to be assessed and prepared to adapt to these major changes. This means providing the best possible support for the development of public agricultural policies and their deployment in the regions. The aim of this thesis is to investigate, in field crops, (I) how climate change (observed and projected) affects competition for resources between weeds and crops; (II) what are the consequences on yields and ecosystem services provided by weeds in different systems (conventional, low-input, organic) and (III) what possible adaptations of systems could be considered in the areas most affected by climate change, towards a no-regrets agro-ecological and climatic transition.

To do this, we will use (1) the latest CMIP6 climate projections for mainland France, produced using an innovative dynamic disaggregation protocol (‘regionalisation’) by the mixed research unit Biogéosciences, which will be verified and validated at the start of the thesis. These data will provide a realistic picture of the climate (trends, variability) on a local scale and will be used as input for a model of weed dynamics in the field: FLORSYS. Developed by the mixed research unit “Agroecology” (INRAE), this model serves as a virtual plot for testing existing and prospective cropping systems. It simulates multiannual changes in weed flora and their consequences (crop yield losses, ecosystem services), based on pedoclimate, crop rotations and cropping techniques.
(2) Inserting high-resolution climate projections into FLORSYS will make it possible to simulate the trajectories of weed flora and their consequences on thousands of cropping systems currently implemented in various arable crop regions, for the near future (2035-2065) and the distant future (2070-2100). It will then be possible to determine the characteristics of the systems that are most robust to climate change (few losses, benefits provided by weeds), and to identify some areas where weed management could be strongly affected by climate change.
(3) Participatory workshops will be held in these areas to co-design resilient systems for the future, in partnership with farmers, technical institutes, researchers and local administrative services. These workshops will aim to rethink current cropping systems in the context of climate change, so as to include weed management strategies identified as being the most sustainable possible. In particular, the aim is to reduce or even eliminate the use of herbicides in favour of combinations of a variety of levers, aimed in particular at maximising the biological regulation of weeds, without compromising the economic profitability of farms and, on a larger scale, food security. The performance of innovative cropping systems will be assessed using FLORSYS simulations.

Keywords

agroecology ; climate change ; weeds ; sustainable crop production

Advisory panel

thesis team + Marie Launay (INRAE Avignon) + Julien Boé (CNRS / CNRM Toulouse)

extrait:

lien_externe:

titre:

Impacts régionalisés du changement climatique sur la nuisibilité des adventices en champs cultivés en France métropolitaine

date_de_debut_these:

septembre 2023

nom:

Cournault

date_de_debut_these_numerique:

20230904

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kc_raw_content:

Downscaled impacts of climate change on the harmfulness of weeds in field crops in mainland France

Started in september 2023

Supervisors: Thierry Castel (MC HDR directeur, BGS - CRC) ; Nathalie Colbach (DR HDR co-directrice, INRAE - UMR Agroécologie, pole gestion des adventices) ; Delphine Moreau (DR HDR co-encadrante, INRAE - UMR Agroécologie, pole gestion des adventices)

Funding: FCPR grant ('formation complémentaire par la recherche') of the French ministry of agriculture and food

 

Abstract

By altering environmental conditions, climate change questions the sustainability of cropping systems and strategies for the agroecological transition. Because of rising temperatures, shifts in the water cycle and reduced use of herbicides, cropping systems need to be assessed and prepared to adapt to these major changes. This means providing the best possible support for the development of public agricultural policies and their deployment in the regions. The aim of this thesis is to investigate, in field crops, (I) how climate change (observed and projected) affects competition for resources between weeds and crops; (II) what are the consequences on yields and ecosystem services provided by weeds in different systems (conventional, low-input, organic) and (III) what possible adaptations of systems could be considered in the areas most affected by climate change, towards a no-regrets agro-ecological and climatic transition.

To do this, we will use (1) the latest CMIP6 climate projections for mainland France, produced using an innovative dynamic disaggregation protocol ('regionalisation') by the mixed research unit Biogéosciences, which will be verified and validated at the start of the thesis. These data will provide a realistic picture of the climate (trends, variability) on a local scale and will be used as input for a model of weed dynamics in the field: FLORSYS. Developed by the mixed research unit “Agroecology” (INRAE), this model serves as a virtual plot for testing existing and prospective cropping systems. It simulates multiannual changes in weed flora and their consequences (crop yield losses, ecosystem services), based on pedoclimate, crop rotations and cropping techniques.
(2) Inserting high-resolution climate projections into FLORSYS will make it possible to simulate the trajectories of weed flora and their consequences on thousands of cropping systems currently implemented in various arable crop regions, for the near future (2035-2065) and the distant future (2070-2100). It will then be possible to determine the characteristics of the systems that are most robust to climate change (few losses, benefits provided by weeds), and to identify some areas where weed management could be strongly affected by climate change.
(3) Participatory workshops will be held in these areas to co-design resilient systems for the future, in partnership with farmers, technical institutes, researchers and local administrative services. These workshops will aim to rethink current cropping systems in the context of climate change, so as to include weed management strategies identified as being the most sustainable possible. In particular, the aim is to reduce or even eliminate the use of herbicides in favour of combinations of a variety of levers, aimed in particular at maximising the biological regulation of weeds, without compromising the economic profitability of farms and, on a larger scale, food security. The performance of innovative cropping systems will be assessed using FLORSYS simulations.

 

Keywords

agroecology ; climate change ; weeds ; sustainable crop production

 

Advisory panel

thesis team + Marie Launay (INRAE Avignon) + Julien Boé (CNRS / CNRM Toulouse)