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Multiple invasions in urbanized landscapes: interactions between the invasive garden ant Lasius neglectus and Japanese knotweeds (Fallopia spp.)
No full textInternational audienceUrbanized landscapes are the theater of multiple simultaneous biological invasions likely to affect spread dynamics when co-occurring introduced species interact with each other. Interactions between widespread invaders call for particular atten- tion because they are likely to be common and because non-additive outcomes of such associations might induce negative consequences (e.g., enhanced population growth increasing impacts or resistance to control). We explored the invasions of two widespread invasive taxa: the Japanese knotweed species complex Fallopia spp. and the invasive garden ant Lasius neglectus, in the urban area of Lyon (France). First, we investigated landscape habitat preferences as well as co-occurrence rates of the two species. We showed that Fallopia spp. and L. neglectus had broadly overlapping environmental preferences (measured by seven landscape variables), but their landscape co-occurrence pattern was random, indicating independent spread and non-obligatory association. Second, as Fallopia spp. produce extra-floral nectar, we estimated the amount of nectar L. neglectus used under field conditions without ant competitors. We estimated that L. neglectus collected 150–321 kg of nectar in the month of April (when nectar production is peaking) in a 1162 m2 knotweed patch, an amount likely to boost ant population growth. Finally, at six patches of Fallopia spp. surveyed, herbivory levels were low (1–6% loss of leaf surface area) but no relationship between ant abundance (native and invasive) and loss of leaf surface was found. Co-occurrences of Fallopia spp. and L. neglectus are likely to become more common as both taxa colonize landscapes, which could favor the spread and invasion success of the invasive ant
Derrière l'utopie du jardin collectif, la complexité d'un projet social, technique et politique
No full textInternational audienceAbstract: While community and allotment gardens can be handled as low cost settlements, as a spontaneous movement of citizens who re-appropriate urban spaces, or as a naïve political object, this paper shows that projects of collective gardens actually refer to a complex process crystallizing various political, technical and social issues. Through the analysis of interactions among stakeholders involved in creation of collective gardens, we show successive redefinitions of the project, based on compromises on materiality, functions and uses of the place between public and community actors, inhabitants, and landlords. Collective garden thus appear as complex urban objects which require an increasing role of professional and experts in social mediation and landscape design, and as highly politicized objects for public and community actors involved. Highlighting this politicization and professionalization, we point out risks of standardization of collective gardens models, which could go against social aspirations.Alors que le jardin collectif, partagé ou familial, peut être perçu comme un aménagement à moindre coût, comme une démarche spontanée de réappropriation de l'espace par des citoyens ou encore comme un objet politique naïf, cet article montre qu'il s'agit d'un projet, processus social et technique plus complexe qui cristallise divers enjeux politiques, techniques et sociaux. L'analyse des dynamiques d'acteurs impliqués dans la création de jardins collectifs révèle des requalifications successives du projet, dans le compromis sur la matérialité, les fonctions du jardin et les usages de l'espace entre collectivités, partenaires locaux associatifs, habitants-futurs jardiniers, bailleurs et aménageurs. Le jardin collectif se présente ainsi comme un objet urbain complexe qui mobilise le recours à une expertise de la médiation sociale et paysagère, et comme un objet politique fort pour les acteurs publics et associatifs impliqués. À la lumière de cette mise en politique et de cette professionnalisation des acteurs médiateurs, nous pointons les risques d'une normalisation des modèles de jardins collectifs pouvant aller à l'encontre des aspirations sociales des habitants
Effect of organic amendments on soil enzymatic activities. Results of the French “Bioindicator program”.
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One-structure-fits-all or how the specific identity of the Permaculture movement fits into the general structure of the networks
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New challenges for education in agroecology
No full textInternational audienceBased on discussions in a workshop associated with the conference The Agroecological Imagination: A Franco-American Exchange, we synthesize the state of agroecological education. We focus on three central questions: the what, how, and who of agroecological education. What are the key competencies, skills, and attitudes for future agroecologists? How do we best teach and learn agroecology? Who the learners and teachers are and should be? With regard to the what, we offer the notion of the expert-generalist who has an expertise but is also trained in integrative and transdisciplinary thinking. With regard to the how, we emphasize the importance of experiential learning and action learning, or active experience, and process for content in context. With regard to the who, we discuss the centrality of recognizing the broad community of agroecology, and the importance of agroecological education reflecting that breadth
Légitimité et positionnement des marchés de gros dans les dynamiques de relocalisation de l’alimentation : les cas du marché de Lyon Corbas et du MIN de Grenoble
No full textInternational audienceLes marchés de gros, lieux de rencontre entre acheteurs et vendeurs professionnels (producteurs, grossistes, détaillants, restaurateurs) pour l’achat et la vente en gros de produits alimentaires, sont conçus pour l’approvisionnement des zones de consommation. Ils sont, depuis plusieurs décennies,confrontés à une concurrence croissantepar les plateformes de la grande distributionetdoivent faire face à une baisse de légitimité de leur fonction liée à la remise en cause des intermédiaires dans les dynamiques de relocalisation de l’alimentation.L’objectif de cet article est d’étudier lesstratégies de relocalisation que lesmarchés de gros développent aujourd’hui,leurpositionnement actuel entre circuits courts et circuits longs, les liens qu’ils essaient de créer à la fois avec leurs territoires etavecles autres acteurs des systèmes alimentaires locaux(producteurs, distributeurs voire consommateurs). A travers l’analyse des stratégies de deux marchés de gros en région Auvergne-Rhône-Alpes, Lyon-Corbas et le MIN de Grenoble, il s’agit de mieux comprendre comment ce positionnement, qui les situe dans un espace hybride, est susceptible de leur redonner,à l’échelle des territoires et des filières,une plus forte légitimitéen tant qu’acteurs des systèmes alimentaires locaux
Effect or organic amendments on soil enzymatic activities. Results of the “Bioindicators” French program
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Utilisation d'un substitut synthétique aux produits d'origine animale pour la cryopréservation d'embryons de lapin et de brebis
No full textEmbryo cryopreservation media usually contain animal-derived products, such as bovine serum albumin (BSA). These products present two major disadvantages: an undefined variable composition and a risk of pathogen transmission. The substitution of animal products of embryo cryopreservation media by synthetical products may improve procedure standardization (by avoiding variability in media composition) and avoid sanitary concerns inherent to animal-derived products.We aimed to evaluate the effect of replacing BSA in rabbit and ovine embryo slow freezing and vitrification media with a synthetic animal products free medium composed of synthetic hyaluronic acid: STEM ALPHA.Cryo3 (« CRYO3 »).During the first part, we evaluated the substitution candidates through a thermodynamic approach, using differential scanning calorimetry. In paralel, we adapted a mitochondrial activity evaluation protocol (JC-1) to rabbit embryo, which allowed us to complement morphological in vitro evaluation, and evaluated ewe superovulation protocols.During the second part, we used a biological approach to evaluate the replacement of BSA with synthetical products (containing CRYO3) in rabbit and ovine embryo slow freezing and vitrification media, using in vitro (slow freezing and vitrification) and in vivo (vitrification) evaluation methods.Our results seem to demonstrate that the chemically defined substitute CRYO3 can successfully replace BSA during rabbit embryo and ovine embryo cryopreservation (slow-freezing and vitrification)Les milieux de cryopréservation d'embryons contiennent généralement des produits d'origine animale, qui présentent des inconvénients majeurs : une composition variable et insuffisamment définie, et un risque de transmission d'agents pathogènes. La substitution de ces produits par des composés synthétiques chimiquement définis pourrait contribuer à l’amélioration des procédures de cryopréservation d’embryons, en réduisant la variabilité de composition des milieux, et le risque de contamination des ressources conservées.L’objectif de ce travail était d’évaluer l’effet du remplacement de l’albumine sérique bovine utilisée dans les milieux de congélation lente ou de vitrification d’embryons cunicoles et ovins par un milieu synthétique formulé à base d’acide hyaluronique (STEM ALPHA.Cryo3 – « CRYO3 »). Dans un premier temps, les propriétés thermodynamiques des substituts potentiels ont été évaluées à l’aide de la calorimétrie différentielle à balayage. Parallèlement, nous avons optimisé les différents outils expérimentaux dont nous avions besoin pour cette étude. Nous avons adapté un protocole d’évaluation de l'activité mitochondriale (JC-1) pour complémenter l'évaluation morphologique in vitro des embryons de lapin, et nous avons évalué l’efficacité de différents protocoles de superovulation sur la production d’embryons chez la brebis. Dans un second temps, nous avons procédé à la substitution de l’albumine sérique bovine (BSA) utilisée dans des milieux de congélation lente et de vitrification d’embryons cunicoles et ovins par du CRYO3. Une approche in vitro a été utilisée pour les protocoles de congélation et de vitrification, puis complétée par une approche in vivo pour les protocoles de vitrification.Nos résultats confirment que la BSA peut être efficacement remplacée par le CRYO3 dans des protocoles de cryoconservation d‘embryons de lapin et d’embryons ovins, qu’il s’agisse de congélation lente ou de vitrificatio
Farmers' involvement in collective experimental designs in a French region, Rhône-Alpes. How do they contribute to farmers' learning and facilitate the agroecological transition?
No full textInternational audienceAgroecology is a promising concept for designing and managing more sustainable agrosystems, but it deeply questions how farmers learn to implement agroecological practices. The building of generic knowledge by scientists is quite insufficient and has to be completed with learning and innovation dynamics on farms. We assume that experimenting agroecological practices on farms is a way for farmers to simultaneously implement and assess new cropping and livestock farming systems, and that the involvement of peers or supporting actors, either scientists or extensionists, could help the experimenting process and favor agroecological transitions. Based on a French participatory research project, we present a cross-case analysis of seven farmers' networks carrying out experiments on crop production and livestock farming. Some experiments were implemented by the farmers themselves on their farms or within a farm network; others were led by technical advisors, veterinarians or scientists. They varied from very formal to much more informal designs and protocols, from individual to more collective experiments. By experimenting, farmers not only assessed the performances of the experimented practices, they also learned how to manage a complex system and observe animals or plants differently, they gained confidence to move to a trajectory of technical change, and in some cases, the experiments stabilized the network for a period by supporting the exchanges between peers. The synergy between individual and collective dynamics was analyzed. Peer-to-peer exchanges provided new ideas and a greater reflexivity on the experiments realized at the individual level. Complementary, the individual experiments were a way to acquire situated knowledge directly usable by each farmer