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Exploring Complementarity Problems: Applications and Specialized Algorithms
No full textInternational audienceComplementarity problems constitute a well-established class of mathematical formulations with broad applicability across various disciplines. Their intrinsic ability to model equilibrium conditions and nonlinear constraints makes them particularly effective for representing complex systems. In this chapter, we explore fundamental concepts associated with complementarity problems, with a focused examination of their application to the analysis and modeling of some classes of dynamical systems
Exploring the moderating role of climate services on flood resilience: Insights from Chinese SMEs
No full textInternational audienceSmall and medium enterprises (SMEs) play a vital role in world economic growth and employment creation, but climate hazards especially floods have become a core risk compromising their production systems, and derailing supply chains. Flood resilience is essential to cater negative effects on SMEs as it protects business assets, minimizes operational disruptions, and ensure quicker recovery. Climate services can assist SMEs in their effort to become flood resilient, as long as services are planned and are according to SME needs. Therefore, this study investigated the moderating effect of climate services on the relationships between six key determinants financial capacity, awareness and risk perception, government support and policy environment, technological capability and innovation, location and exposure, social networks and partnerships, and the flood-resilience of SMEs. The data were collected from 250 SMEs using multistage stratified random sampling technique from three Chinese provinces through face-to-face surveys. The collected data were analyzed using partial least squares structural equation model. The findings showed that more financial capacity, greater awareness and perceived risk associated with floods, innovative and technological capability, and strong social networks and partnerships may facilitate flood resilience of SMEs. The findings revealed that climate services significantly moderate the relationship between awareness and risk perception, government support and policy environment, technological capability and innovation, location and exposure, social networks and partnerships and flood resilience outcomes of SMEs. These findings underscore the critical role of climate services in strengthening SMEs flood resilience and provide a robust framework for integrating climate information into SME disaster-risk management
Participatory modelling for agroecological transitions: engaging stakeholders in transformative pathways
No full textInternational audienceCONTEXT. The worldwide use of synthetic pesticides has been rising for decades. Agroecology offers a promising alternative, but its adoption requires support from public policy and multi-scale institutional and social levers. Recent policy approaches integrate levers promoting collective and territorial collaboration, recognizing the local scale as crucial for agroecological transitions. These levers involve mobilizing territorial stakeholders and implementing context-specific levers.OBJECTIVE. Our objective is to better understand territorial levers that support agroecological transformation and associated practice change dynamics. We engaged with stakeholders using a generic territorial socio-ecological model to identify local levers and potential agroecological transition pathways.METHODS. In the Barrois region (Eastern France), a participatory modelling initiative involved stakeholders from a farming territory aiming to reduce pesticide use. Three participatory workshops were organized to: (1) identify context-relevant levers; (2) calibrate the model based on the territory's current state; and (3) explore agricultural trajectories and supporting levers.RESULTS AND CONCLUSIONS. The use of the model highlights the dynamic and multi-factor nature of transitions. The workshops fostered rich dialogue and proposals, playing a central role in co-construction. Participants collectively identified levers such as awareness-raising, training initiatives, new stakeholder networks, and evolving advisory services. However, these levers vary depending on farmers' sensitivities and production types. Discussions emphasized the importance of involving not only farmers but also consumers and supply chains to drive change.SIGNIFICANCE. This participatory approach produced a more realistic model and created learning opportunities for all participants (researchers and agricultural stakeholders), despite challenges like communicating complex theoretical concepts and vocabulary
Combiner instruments de politique et mesures locales pour promouvoir l'agrobiodiversité
No full textInternational audienceDie Agrobiodiversität ist generell rückläufig. In der Literatur wird zwar die Rolle der öffentlichen Politik in diesem Prozess hervorgehoben, jedoch besteht nach wie vor eine Forschungslücke hinsichtlich der Frage, wie politische Maßnahmen dazu beitragen können, diesen Trend umzukehren. Ein Ansatz besteht darin, landwirtschaftlichen Betrieben, die Wert auf Pflanzen‐ und Sortenvielfalt legen, wirtschaftliche Unterstützung zu gewähren. Dieser Artikel gibt auf der Grundlage einer Literaturrecherche und von Experteninterviews zunächst einen Überblick über europäische und nationale politische Instrumente, die zur wirtschaftlichen Förderung der Agrobiodiversität in landwirtschaftlichen Betrieben eingesetzt werden können. Der Schwerpunkt liegt dabei auf sieben europäischen Ländern. Anschließend wird auf der Basis von Fallstudien eine Typologie lokaler Initiativen vorgestellt, die diese Instrumente mit Maßnahmen kombinieren. So können landwirtschaftliche Betriebe, die Nebenkulturen und traditionelle Sorten anbauen, wirtschaftlich gefördert werden. Diese Förderung ist in erster Linie indirekter Natur und reicht von der Bereitstellung von Saatgut bis zur Marktentwicklung, wobei die meisten Initiativen nicht die gesamte Wertschöpfungskette abdecken. Die Ergebnisse unterstreichen die entscheidende Rolle der lokalen Behörden und bestätigen den Wert öffentlich‐privater Partnerschaften bei der Förderung der Pflanzen‐ und Sortenvielfalt. Sie betonen auch die Notwendigkeit einer stärkeren Koordinierung zwischen politischen Maßnahmen und Governance‐Ebenen, um die Wertschöpfungsketten zu stärken, die Agrobiodiversität unterstützen. Zudem werden weitere Untersuchungen gefordert, um zu bewerten, welchen Beitrag die kombinierte Unterstützung durch politische Instrumente und lokale Maßnahmen zu neuen Geschäftsmodellen auf Ebene der landwirtschaftlichen Betriebe leistet.Agrobiodiversity is in decline. While the literature highlights the role of public policy in this process, a research gap remains concerning how policies can help reverse this trend by providing economic support to farms that value crop and varietal diversity. Based on desk research and expert interviews, this article first provides an overview of European and national policy instruments that can be used to economically support the promotion of agrobiodiversity on farms, focusing on seven European countries. Drawing on case study findings, it then presents a typology of local initiatives that combine these instruments with local measures to provide economic support to farms cultivating minor crops and traditional varieties. This support is primarily indirect, ranging from seed provision to market development, although most initiatives do not cover the entire value chain. The results underline the critical role of local authorities and confirm the value of public‐private partnerships in promoting crop and varietal diversity. They also emphasise the need for stronger coordination between policy measures and governance levels to support value chains that foster agrobiodiversity, and call for further research to assess how the combined support of policy instruments and local measures contributes to new business models at farm level.L’agrobiodiversité est en déclin . Si la littérature souligne le rôle des politiques publiques dans ce processus, des lacunes subsistent quant à la manière dont ces politiques peuvent contribuer à inverser cette tendance en apportant une aide économique aux exploitations agricoles qui valorisent la diversité des espèces et des variétés végétales. S’appuyant sur une recherche documentaire et des entretiens avec des experts, cet article présente d’abord un aperçu des instruments de politique européens et nationaux qui peuvent soutenir économiquement l’utilisation de l’agrobiodiversité dans les exploitations agricoles, en se concentrant sur sept pays européens. Avec l’appui d’études de cas, il propose ensuite une typologie d’initiatives locales combinant ces instruments à des mesures locales pour apporter une aide économique aux exploitations cultivant des cultures mineures et des variétés traditionnelles. Ces aides sont principalement indirectes, allant de la fourniture de semences au développement des marchés, mais la plupart des initiatives ne couvrent pas l’intégralité de la chaîne de valeur. Les résultats soulignent le rôle crucial des collectivités territoriales et confirment l’intérêt des partenariats public‐privé pour la promotion de la diversité des cultures et des variétés. Ils mettent également en évidence la nécessité d’une coordination renforcée entre les mesures gouvernementales et les différents niveaux de gouvernance afin de soutenir les chaînes de valeur favorisant l’agrobiodiversité. Enfin, ces résultats appellent à des recherches complémentaires pour évaluer comment le soutien combiné des instruments de politique et des mesures locales contribue à l’émergence de nouveaux modèles économiques au niveau des exploitations
The evolving landscape of farmland ownership in Europe: implications for food system sustainability
No full textInternational audienceThis study examines the evolving dynamics of farmland ownership in Europe, focusing on the implications of ownership changes, foreign direct investments (FDI), and land concentration on the sustainability and resilience of European food systems. A scoping review of academic literature, available data sources, and policy documents revealed a knowledge gap regarding the evolution of European farmland ownership and its sustainability impacts. To address this, a pan-European geospatial statistical analysis was conducted, identifying ownership patterns, temporal changes and related economic performance. Subsequently, the statistical analysis provides a foundation to assess how ownership transformations affect food system sustainability and resilience. Findings show that in 2020, family farms were the dominant landowners across Europe. However, between 2016 and 2020, a shift toward company-owned farms occurred, particularly in Central and Eastern Europe. Drawing on global research on land acquisitions and sustainable agriculture, the study underscores that while companyowned farms may offer economic efficiencies, family farm ownership is vital for food security and local control over land and production. The study calls for continued monitoring of ownership trends and deeper investigation into their benefits, risks, and consequences. It recommends policy measures that balance investment incentives in the European food system with protections for local communities, that promote transparency in land transactions, and safeguard the long-term sustainability of European agriculture by upholding labor and environmental standards
TimeSenCLIP: A time series vision–language model for remote sensing
No full textInternational audienceVision-language models (VLMs) have shown significant promise in remote sensing applications, particularly for land-use and land-cover (LULC) mapping via zero-shot classification and retrieval. However, current approaches face several key challenges, such as the dependence on caption-based supervision, which is often not available or very limited in terms of the covered semantics, and the fact of being adapted from generic VLM architectures that are suitable for very high resolution images. Consequently, these models tend to prioritize spatial context over spectral and temporal information, limiting their effectiveness for medium-resolution remote sensing imagery. In this work, we present TimeSenCLIP, a lightweight VLM for remote sensing time series, using a cross-view temporal contrastive framework to align multispectral Sentinel-2 time series with geo-tagged ground-level imagery, without requiring textual annotations. Unlike prior VLMs, TimeSenCLIP emphasizes temporal and spectral signals over spatial context, investigating whether single-pixel time series contain sufficient information for solving a variety of tasks. Our approach is trained on the LUCAS and Sen4Map datasets and evaluated across four main mapping tasks: land cover, land use, habitat mapping and crop type classification. The CLIP text encoder can be used to probe the learned representations using semantically meaningful categories, enabling effective zero-shot generalization without task-specific text supervision. We further extend our evaluation to bioregions mapping and country-level image retrieval. Although coarse, these tasks are valuable for probing whether the model captures geographically meaningful representations, such as regional climate regimes, vegetation patterns, and land-use structures. TimeSenCLIP achieves consistently better performance than existing CLIP-based remote sensing models in both zero-shot classification and cross-modal retrieval. Notably, single-pixel multispectral time series variants remain highly competitive, particularly with extended temporal coverage, demonstrating that temporal-spectral dynamics can compensate to a substantial degree for the reduced spatial footprint. While larger spatial patches still offer advantages for tasks where spatial patterns are inherently informative, such as ecosystem type classification, the results suggest that single-pixel multispectral time series can provide effective remote sensing vision-language pipelines, supporting scalable and efficient modelling in scenarios where large spatial tiles or extensive textual annotations are impractical
Evaluation of sanitary and environmental impact of plant protection practices in vineyards of Southwestern France: organic and conventional/integrated agriculture
No full textInternational audienceThe French wine industry is spread across the country and represents 789,000 ha (2023). Over 20% of the plant protection products (PPPs) sold in France are used in viticulture on less than 4% of the French UAA (Utilized Agricultural Area). The share of wine estates with organic farming certification has risen sharply, reaching 9% of French vineyards in 2016. The position occupied by the wine sector on both the national and international scale confirms the need to examine the impacts of different management practices in viticulture on human health and the environment. This study presents an approach to the assessment of plant protection practices in vineyards based on indicators of plant protection pressure and risk. It was carried out on wine-growing farms in the southwest of France, surveyed according to the two farming systems: conventional/integrated and organic. The main objective of this study was to compare the health and environmental impact of the PPPs used in these two farming systems. The impact assessment result of wine-growing plant protection practices shows that some pesticides and molecules used in organic farming, especially those based on copper and sulfur, are more harmful than products used in conventional/integrated farming, in particular to the environment. For this reason, all stakeholders involved in pesticide management should recognize the health and environmental impact of PPPs in order to reduce and to control their toxicity risks to public health and the natural environment
Multidimensional and multiscale evaluation framework considering Water–Energy–Food–Ecosystem Nexus
No full textInternational audienceThe agricultural sector in the Mediterranean Basin is the largest consumer of water, using 70% of freshwater resources for crop irrigation, which accounts for 85% of the region's agricultural output. With climate change and population growth expected to reduce water availability, energy management also poses a significant challenge, as 7% of commercial energy is used for freshwater supply. The DIONYSUS project aims to develop practical adaptation solutions for efficient resource use through innovative business models, focusing on four demonstration sites in Egypt, Greece, Morocco, and Italy. It seeks to promote a transition to a Green Economy by engaging stakeholders and utilizing a Cross-Sectoral Nexus adaptation tool
Enforcing contracts: the role of state subsidies as a hybrid enforcement mechanism in contracts between tomato processors and farmers in Algeria
No full textInternational audienceMotivation: Contract farming plays a significant role in the growth of agriculture in many countries. Contracting poses substantial challenges when courts and companies are insufficiently developed, constraining the fulfilment of contracts. Exploring innovative contract enforcement mechanisms could yield valuable insights.Purpose: We evaluate the effectiveness of state subsidies as a hybrid enforcement mechanism of the marketing contract developed by the Algerian government for tomato processors and their farmer suppliers.Approach and methods: We examine the delivery decisions of Algerian tomato farmers to honour contracts or to deliver to the spot market. From the findings we evaluated the direct and indirect effects of subsidies on expanding the self-enforcing range of contracts and on encouraging firms to establish private contract enforcement mechanisms. Propensity scoring was used to match farmers. The data come from a comprehensive database of contracted tomato producers and surveys of all tomato canneries in 2021.Findings: Subsidies, by reducing processor costs and raising famer prices, help to make contracts self-enforcing. Subsidies, moreover, encouraged half of the processors to adopt private contract enforcement mechanisms, above all loans to their supplier farmers. These mechanisms have had a positive, albeit moderate, effect on farmer deliveries. Farmers still deliver only half of their contracts owing to weakening self-enforcement as the subsidy can be accessed in the spot market.Policy implications: Public subsidies can help enforce contracts in agricultural value chains, especially where legal systems are fragile. Strict control of access to subsidies and incentives is crucial to ensure that the contract price provides sufficient incentive to farmers and to encourage processors to provide additional incentives
Economic valuation of groundwater over-exploitation in the Maghreb
No full textInternational audienceThe agricultural sector is recognized as particularly vulnerable to the effects of climate change. In semi-arid areas, the performance and durability of irrigated systems are often difficult to manage. Understanding agriculture's response to water scarcity, institutional change and policy interventions is important in order to better define the different agricultural development pathways. The purpose of this paper is to carry out an economic assessment of the costs of groundwater over-exploitation in the Maghreb. This was achieved by using bioeconomic modeling in three case studies: the Saïss plain (Morocco), El Haouaria plain (Tunisia) and Sétif plain (Algeria). A set of indicators (land use, farm gross margin, the dual value of water and labor requirements) was calculated for each case study in two scenarios (a business-as-usual (S_BAU) scenario and a return-toequilibrium (S_RtE) scenario) over a period of 15 years, from 2021 to 2035. Our results show that (i) the state of the aquifer and its over-exploitation level determine the extent of future changes; (ii) in the case of significant groundwater over-exploitation, restoration costs are higher than over-exploitation costs (Saïss plain); on the other hand, in the case where the over-exploitation rate is lower (El Haouaria and Sétif plains), the overexploitation and restoration costs are close; (iii) both scenarios show significant structural and social changes, and without the effective implementation of environmental and social policies, they lead to high economic losses