HAL-CIRAD
Not a member yet
54841 research outputs found
Sort by
Mieux manger dans la restauration collective: un processus d'essai et d'erreurs. L'exemple du lycée agricole Grandgousier: Rapport du projet Ecolo-Acte
No full textMulti-scale patterns in the structure of fish and fouling communities associated with seaweeds in marinas
No full textInternational audienceRedistribution of biodiversity represents a key challenge for understanding scales of spatial variations in natural marine communities. With increasing coastal urbanization, artificial structures are proliferating with impacts on natural habitats yet there is poor knowledge on the spatial scales of processes operating over their associated species assembly. This is exemplified by novel communities establishing along and around floating infrastructures, such as pontoons in marinas. Here we explored the multi-scale patterns in the diversity and community structure of fouling seaweeds, invertebrates and fish communities associated with pontoons in 18 marinas, distributed along about 1000 km of coastline in NW France. With respect to the marina's distribution across three distinct ecoregions, we predicted that their seaweed communities would follow spatial patterns reported in native communities from rocky shores. This hypothesis was poorly supported, and the variation among ecoregions (8%) was largely explained by the abundance of nonindigenous kelps. However, as anticipated, we observed important variability among and within marinas in all response variables (e.g. richness of sessile invertebrates and fish). These variations were related to contrasting sea surface temperature regimes among marinas, along with a number of explanatory variables (e.g. distance to marina entry) As also hypothesized, fouling and fish communities covaried with kelp biomass, although covariations were strengthened at the scale of the region and at the scale of the marina and pontoon when nonindigenous and native kelp were considered, respectively. Specificities in distributions and influences of foundation species in urban environments could be worth scrutinizing for their management
Changements dans la filière porcine dans le sud Vietnam
No full textThe pig industry in Vietnam has been transformed by complex interactions between local, national and global dynamics. The chapter 1 explains the substantial changes that have affected the agricultural sector in Vietnam as a result of historical events, policy shifts, technological advancements and changes in social practices by using a sociotechnical transition framework and a value chain approach. The findings show that while the collapse of collectivism opened the way for the smallholder regime in the late 1980s, which rapidly empowered these actors and dominated in the 1990s. Our results also highlight the critical role of institutions and policies. The land issue emerges as a linchpin. Recognizing the importance of family farms and the new land reforms dissipated the historical bottlenecks, paving the way for the development of larger farms. Foreign direct investment emerged as a transformative force, serving not only as an economic stimulus, but as a conduit for spillover effects, introducing new technologies and fostering a competitive environment. The interplay of sociotechnical regimes, institutional dynamics, global events and foreign investment shaped a narrative of resilience, adaptation and restructuring in Vietnam's pig industry.Chapter 2 investigates corporate strategies and their impact on the levels of integration within the pig value chain. It challenges the conventional view that changes primarily emerge downstream in value chains. By focusing on the restructuring upstream, the chapter explores the development of the contract farming model and the subsequent wave of investment in the livestock industry. The chapter then describes the significant impact of African Swine Fever (ASF) in 2019. Chapter 2 highlights the strategic shifts triggered by external shocks and the resulting financial challenges by testing the hypothesis that African swine fever causes a high level of uncertainty and creates a need to invest in specific assets that favor vertical integration in the pig chain, which may be at the expense of small farmers. Our results show that small farmers are elbowed out and replaced to a large extent by modern actors. More concerned about higher investments in biosecurity, modern farming (both contract farming and mega farm models) take its advance to be predominant. Foreign Direct Investment (FDI) in animal-feeding companies and domestic investors favor the mega farm model. By transferring ownership of physical assets, FDI-feeding companies move from contract integration to ownership integration, thereby achieving their strategy of centralizing power.The study goes beyond conventional value chain analyses, by introducing a key actor, the “Dau”, which operates in the "hidden middle" of the pig value chain. The result shows that Dau actor is distinct from conventional agents, as documented in the literature. Dau has a multifaceted role. Therein, Dau provides financial support for wholesale sellers (WS), by acting as a financial middleman and offering credit services. This unique feature distinguishes the Dau from other actors in the value chain. Using an institutional approach and by drawing on a historical analysis, the study provides insights into how the Dau's role contributes to the stability of the pig value chain. The Dau's credit services are identified as a crucial stabilizing force both upstream and downstream in the pig sector. The Dau facilitates the continuous circulation of money for collectors/traders upstream, which ensures the steady flow of goods downstream. The financial support provided by the Dau has two essential functions. First, it provides facilities to postpone the payment for pork cut wholesalers and retailers, which means there is a seamless flow of goods. Second, the Dau's financial guarantee is of high importance for collectors/traders, who link the upstream (production areas) and the middle segment (wholesale markets), thus maintaining stability upstream.La filière porcine au Vietnam a été transformée par des interactions complexes entre des dynamiques locales, nationales et globales. Le chapitre 1 explique les changements majeurs qui ont impacté le secteur agricole au Vietnam à la suite d’évènements historiques, de changements de politiques, d’avancées technologiques et de l’évolution dans les pratiques sociales par utiliser un cadre de transition sociotechnique et une approche centrée sur la chaîne de valeur. Les résultats montrent que, même si l’effondrement du collectivisme a ouvert la voie au régime des petits exploitants à la fin des années 1980, celui-ci a rapidement donné du pouvoir à ces acteurs et a dominé dans les années 1990. Nos résultats soulignent le rôle essentiel des institutions et des politiques. L’enjeu foncier apparaît comme un élément central. La reconnaissance de l’importance des exploitations familiales et les nouvelles réformes agraires ont dissipé les blocages historiques, ouvrant la voie au développement d’exploitations plus grandes. L’investissement direct étranger est apparu comme une force de transformation, agissant non seulement comme une relance économique, mais aussi comme un canal d’effets indirects introduisant de nouvelles technologies et favorisant un environnement compétitif. L’interaction des régimes sociotechniques, des dynamiques institutionnelles, des évènements mondiaux et des investissements étrangers a modelé un récit de résilience, d’adaptation et de restructuration dans la filière porcine au Vietnam.Le chapitre 2 explore les stratégies des grands groupes et leur impact sur les niveaux d’intégration au sein de la chaîne de valeur porcine. Il remet en cause la vision traditionnelle selon laquelle les changements surgissent d’abord en aval des chaînes de valeur. En examinant la restructuration en amont de la chaîne de valeur, le chapitre étudie le développement du modèle d’exploitation sous contrat et la vague d’investissements dans le secteur de l’élevage qui a suivi. Le chapitre 2 met en évidence les changements stratégiques déclenchés par les chocs externes et les défis financiers qui en résultent en testant l'hypothèse selon laquelle la peste porcine africaine entraîne un niveau élevé d'incertitude et crée un besoin d'investir dans des actifs spécifiques qui favorisent l'intégration verticale dans la chaîne porcine, ce qui peut se faire au détriment des petits exploitants. Nos résultats montrent que les petits exploitants sont évincés et remplacés dans une large mesure par des acteurs modernes. Plus préoccupée par des investissements plus importants en matière de biosécurité, l'agriculture moderne (à la fois l'agriculture contractuelle et les modèles de méga-fermes) prend de l'avance pour devenir prédominante. Les investissements étrangers directs (IED) dans les entreprises d'alimentation animale et les investisseurs nationaux favorisent le modèle de la méga-ferme. En transférant la propriété des actifs physiques, les entreprises d'alimentation animale financées par l'IDE passent de l'intégration contractuelle à l'intégration de la propriété, réalisant ainsi leur stratégie de centralisation du pouvoir.L’étude va plus loin que les analyses des chaînes de valeur classiques, en introduisant le « Dau », acteur clé opérant au « centre caché » de la chaîne de valeur porcine. Le Dau se distingue des agents traditionnels documentés dans la littérature. Son rôle est multiple, dépassant celui de facilitateur de transactions. Le Dau offre un soutien financier aux grossistes, en agissant comme intermédiaire financier et proposant des services de crédit. Cette caractéristique unique différencie le Dau des autres acteurs dans la chaîne de valeur. En adoptant une approche institutionnelle et en s’appuyant sur une analyse historique, l’étude montre comment le rôle du Dau contribue à la stabilité de la chaîne de valeur porcine. Les services de crédit du Dau sont identifiés comme une force stabilisatrice cruciale, tant en amont qu’en aval de la filière porcine
A single changing hypernetwork to represent (social-)ecological dynamics
No full textInternational audienceTo understand and manage (social-)ecological systems, we need an intuitive and rigorous way to represent them. Recent ecological studies propose to represent interaction networks into modular graphs, multiplexes and higher-order interactions. Along these lines, we argue here that non-dyadic (non-pairwise) interactions are common in ecology and environmental sciences, necessitating fresh concepts and tools for handling them. In addition, such interaction networks often change sharply, due to appearing and disappearing species and components. We illustrate in a simple example that any ecosystem can be represented by a single hypergraph, here called the ecosystem hypernetwork. Moreover, we highlight that any ecosystem hypernetwork exhibits a changing topology summarizing its long term dynamics (e.g., species extinction/invasion, pollutant or human arrival/migration). Qualitative and discrete-event models developed in computer science appear suitable for modeling hypergraph (topological) dynamics. Hypernetworks thus also provide a conceptual foundation for theoretical as well as more applied studies in ecology (at large), as they form the qualitative backbone of ever-changing ecosystems
SelNeTime: a python package inferring effective population size and selection intensity from genomic time series data
No full textSummary Genomic samples collected from a single population over several generations provide direct access to the genetic diversity changes occurring within a specific time period. This provides information about both demographic and adaptive processes acting on the population during that period. A common approach to analyze such data is to model observed allele counts in finite samples using a Hidden Markov model (HMM) where hidden states are true allele frequencies over time (i.e. a trajectory). The HMM framework allows to compute the full likelihood of the data, while accounting both for the stochastic evolution of population allele frequencies along time and for the noise arising from sampling a limited number of individuals at possibly spread out generations. Several such HMM methods have been proposed so far, differing mainly in the way they model the transition probabilities of the Markov chain. Following Paris et al. (2019a), we consider here the Beta with Spikes approximation, which avoids the computational issues associated to the Wright-Fisher model while still including fixation probabilities, in contrast to other standard approximations of this model like the Gaussian or Beta distributions. To facilitate the analysis and exploitation of genomic time series data, we present an improved version of Paris et al. (2019a) ‘s approach, denoted SelNeTime, whose computation time is drastically reduced and which accurately estimates effective population size in addition to the selection intensity at each locus. This method is implemented in a user friendly python package, which also allows to easily simulate genomic time series data under a user-defined evolutionary model and sampling design
Agroecology as a new frame of reference for French agricultural policy? Insights from a lexicometric analysis of policy documents
No full textInternational audienceReferences to agroecology have gradually started appearing in national and international public policies. We examine the extent to which agroecology is becoming a frame of reference for public action in the French national and regional context. Using textual statistics, we analyzed institutional documents concerning agroecology put out by public policy actors between 2008 and the summer of 2021, and conducted interviews with key actors of the Agroecological Project for France (PAEF, Projet Agroécologique pour la France). Our analysis shows that agroecology invoked in framing texts is reclassified in the vocabulary of triple performance, dominated by the notion of economic performance. A comparative analysis of the national and regional texts reveals mismatches, especially in terms of the level of autonomy of the actors concerned, and in the processes of knowledge transfer and support for changes in agricultural practices
Monitoreo longitudinal de la dinámica de movilización-reconstitución de reservas corporales en rebaños bovinos comerciales de Camagüey, Cuba
No full textInternational audienceEn el marco del proyecto ProLAIF Agro Verde financiado por la Unión Europea, se implementa un primer estudio para las condiciones de Cuba con vistas a caracterizar la capacidad adaptativa del ganado vacuno en las condiciones actuales de cambio climático. Con una muestra de ocho fincas comerciales distribuidas en cuatro municipios de la provincia de Camagüey, se seleccionó alrededor del 10 al 15% de las vacas pie de crías en cada rebaño (total, n= 109), con el objetivo de realizar un monitoreo longitudinal (dos años; 2024-2026) de variables morfológicas relacionadas con el estado corporal (peso vivo, PV; y condición corporal, CC) y el metabolismo energético de los individuos (mediante extracción de plasma sanguíneo; metabolitos. En paralelo, se ejecutaron entrevistas semiestructuradas a los productores para realizar un diagnóstico detallado de las prácticas de manejo que caracterizan los sistemas de alimentación-nutrición de cada una de las fincas a lo largo de un año típico y en función de los estados fisiológicos de las vacas del rebaño; y, por otra parte, se monitorean diariamente (desde 2019) las variables medioambientales de los enclaves específicos en los que desarrollan los trabajos. La caracterización fina y longitudinal de la dinámica de reservas corporales (DRC) permitirá 1) llevar a cabo interpretaciones multifactoriales de los principales factores que determinan la incidencia de episodios con balance energético negativo en el conjunto de fincas que participan en el proyecto; 2) la identificación de periodos claves de subalimentación y subnutrición a veces subestimados en el manejo de los rebaños; 3) la determinación de la variabilidad interindividual en la eficiencia de utilización de las RC, con declinación a la contribución relativa de los componentes del manejo, fisiológicos, genéticos, genómicos o de interacción genotipo-ambiente más relevantes. El estudio contribuirá al avance del conocimiento y del estado del arte en esta temática relativamente nueva (primicia para Cuba) y a la posibilidad de hacer propuestas concretas para mejorar los sistemas de alimentación-nutrición, de selección y mejora de la capacidad adaptativa de los bovinos en Cuba
