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Quelles sont les conditions au maintien de l’intégration culture – élevage ? Analyse rétrospective dans le Gers, de 1950 à nos jours
No full textInternational audienc
Ecological dynamic regimes: A key concept for assessing ecological resilience
No full textInternational audienceThe increasing incidence of extreme events combined with long-term pressures due to climate change and anthropogenic activities are seriously threatening ecosystems worldwide. Promoting ecological resilience (i.e., the ability of ecosystems to absorb changes and maintain their processes and functioning) is a pivotal target for biological conservation. Many empirical approaches to assess resilience have relied on the underlying assumption that, in the absence of disturbances, ecosystems would be in a ‘static’ baseline state. In reality, ecological systems are highly dynamic and undergo phases of development and reorganization resulting from natural successional changes and their response to multiple interacting variables. As such, ecosystem states can be better described by ‘dynamic regimes’ rather than stationary states. In this context, there is an urgent need to expand the common ‘equilibrium-based’ approaches used in empirical ecology to evaluate resilience so that they can be applied to non-static ecosystems. Here, we present our perspective on the relevance of approaches based on dynamic regimes to assess ecological resilience empirically. More specifically, we briefly review the concept of resilience and discuss the main challenges for empirical applications. Then, we review an approach based on ecological dynamic regimes and temporal trajectories that can be used to assess the ecological resilience of non-static ecosystems from empirical data. Approaches focused on dynamic regimes help evaluate the management effort necessary to restore a disturbed ecosystem. Besides, they facilitate the identification of the factors that must receive special attention for enhancing ecosystem resilience
Reuse out-of-year data to enhance land cover mapping via feature disentanglement and contrastive learning
No full textTimely up-to-date land use/land cover (LULC) maps play a pivotal role in supporting agricultural territory management, environmental monitoring and facilitating well-informed and sustainable decision-making. Typically, when creating a land cover (LC) map, precise ground truth data is collected through time-consuming and expensive field campaigns. This data is then utilized in conjunction with satellite image time series (SITS) through advanced machine learning algorithms to get the final map. Unfortunately, each time this process is repeated (e.g., annually over a region to estimate agricultural production or potential biodiversity loss), new ground truth data must be collected, leading to the complete disregard of previously gathered reference data despite the substantial financial and time investment they have required. How to make value of historical data, from the same or similar study sites, to enhance the current LULC mapping process constitutes a significant challenge that could enable the financial and human-resource efforts invested in previous data campaigns to be valued again. Aiming to tackle this important challenge, we here propose a deep learning framework based on recent advances in domain adaptation and generalization to combine remote sensing and reference data coming from two different domains (e.g. historical data and fresh ones) to ameliorate the current LC mapping process. Our approach, namely REFeD (data Reuse with Effective Feature Disentanglement for land cover mapping), leverages a disentanglement strategy, based on contrastive learning, where invariant and specific per-domain features are derived to recover the intrinsic information related to the downstream LC mapping task and alleviate possible distribution shifts between domains. Additionally, REFeD is equipped with an effective supervision scheme where feature disentanglement is further enforced via multiple levels of supervision at different granularities. The experimental assessment over two study areas covering extremely diverse and contrasted landscapes, namely Koumbia (located in the West-Africa region, in Burkina Faso) and Centre Val de Loire (located in centre Europe, France), underlines the quality of our framework and the obtained findings demonstrate that out-of-year information coming from the same (or similar) study site, at different periods of time, can constitute a valuable additional source of information to enhance the LC mapping process
Drought responses in Coffea arabica as affected by genotype and phenophase. I – leaf distribution and branching
No full textInternational audienceIn Coffea arabica , there is a small genetic distance between wild and bred genotypes. However, coffee genotypes express differential acclimation to multiple drought cycles, allowing them to successfully deal with water-limiting conditions. We hypothesized that bred coffee cultivars have a plant structure less sensitive to drought than wild genotypes. Plant and leaf architecture were analyzed over the coffee strata of two cultivars (Iapar 59 and Catuaí 99) and two wild Ethiopia accessions (‘E083’ and ‘E027’) grown under rainfed conditions and irrigation. During two consecutive productive years, evaluations were taken at leaf and berry expansion (BE1 and BE2) and harvest (BH1 and BH2) phenophases. The plant canopy was divided into up to four strata of 40 cm of thickness. Topological and geometric coding of coffee trees was performed in three botanical scales – metamers, branches, and plants in multiscale tree graphs (MTGs), following the VPlants modeling platform. Leaf and branch area per plant increased with tree structure development, being always significantly higher in irrigated than in rainfed plants over all phenophases. The individual leaf area was the least sensitive to water regime in Catuaí 99, while the 2 nd order axis elevation – angle in relation to horizontal plane, ranging from 0° to 90° – of bred cultivars was less sensitive to drought than in ‘E083’. This finding partially corroborated our hypothesis that orchestrated reprograming of leaf/branch responses over the vertical plant profile were less sensitive to water availability in cultivars than in wild accessions. Leaves of 2 nd to 4 th -order branching were roughly plagiophile, while the 1 st -order leaves were classified as extremophiles. When the coffee leaves were planophile, irrespective of genotype, this pattern was found at the lowest, 1 st plant stratum, and the newest developed 4 th stratum. Such responses were not obligatorily related to water regime, similar to branch elevation – with exception of ‘E083’, very sensitive to drought. Taken together, our data suggest that the leaf and branch elevations in C. arabica were more influenced by light distribution through the canopy profile – i.e., self-shading – than by water availability
Intraspecific niche models for the invasive ambrosia beetle Xylosandrus crassiusculus suggest contrasted responses to climate change
No full textInternational audienceXylosandrus crassiusculus is an invasive ambrosia beetle comprising two differentiated genetic lineages, named cluster 1 and cluster 2. These lineages invaded different parts of the world at different periods of time. We tested whether they exhibited different climatic niches using Schoener's D and Hellinger's I indices and modeled their current potential geographical ranges using the Maxent algorithm. The resulting models were projected according to future and recent past climate datasets for Europe and the Mediterranean region. The future projections were performed for the periods 2041-2070 and 2071-2100 using 3 SSPs and 5 GCMs. The genetic lineages exhibited different climate niches. Parts of Europe, the Americas, Sub-Saharan Africa, Asia, and Oceania were evaluated as suitable for cluster 1. Parts of Europe, South America, Central and South Africa, Asia, and Oceania were considered as suitable for cluster 2. Models projection under future climate scenarios indicated a decrease in climate suitability in Southern Europe and an increase in North Eastern Europe in 2071-2100. Most of Southern and Western Europe was evaluated as already suitable for both clusters in the early twentieth century. Our results show that large climatically suitable regions still remain uncolonized and that climate change will affect the geographical distribution of climatically suitable areas. Climate conditions in Europe were favorable in the twentieth century, suggesting that the recent colonization of Europe is rather due to an increase in propagule pressure via international trade than to recent environmental changes
Adapting service crop termination strategy in viticulture to increase soil ecosystem functions and limit competition with grapevine
No full textDuring the preparation of this work the author(s) used Chat-GPT in order to translate French text into English, or detect English language errors. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.International audienceSoil management and particularly service crops are a promising solution for addressing current challenges in viticulture as they limit the use of herbicides while increasing potential ecosystem services. Scientific literature barely considers the importance of service crop management to reach trade-offs between ecosystem services and disservices. This study evaluates during a three-year experiment, 6 service crop termination strategies for winter service crops, combining two service crops termination periods (early termination in February vs. termination at grapevine budburst) and three termination methods (mower (M), mower + tillage (T), roller-crimper (R)). Service crop (biomass, C:N ratio, weeds, and mulch following termination), soil ( soil organic matter, microbial biomass, and water and nitrogen stocks), and grapevines (predawn leaf water potential, yield components, δ13C, yeast assimilable nitrogen in juice, and pruning weight) were monitored from 2019 to 2022. Allowing service crops to develop until the budburst of the vine resulted in a two to three-fold increase in biomass compared to early destruction. Termination involving soil tillage was the most effective method, as treatments destroyed early with soil tillage exhibited almost no regrowth. Soil tillage termination led to the lowest biomass of weeds at the grapevine flowering two years out of three, and prevented the regrowth of certain sown plants, especially Poaceae. The roller was less effective in destroying service crop species but was the best method for maintaining plant residues on the soil surface. A higher soil microbial biomass was observed with termination at budburst, combined with no-till termination methods. Termination involving soil tillage was notably more effective in stopping service crop transpiration, increasing soil water stocks and improving grapevine water status. In 2020 and 2022, soil inorganic nitrogen stocks were almost 4 times higher in the T treatments compared to the other two termination methods, achieving a level of approximately 61 kg ha−1 that closely corresponds to the annual nitrogen requirements of grapevines. The yeast-assimilable nitrogen (YAN) content in grape juice mirrored this trend. Pruning weight varied significantly between different termination methods, with T treatments exhibiting a higher pruning weight per vine in comparison to R and M treatments. In general terms, the T treatment had a significantly higher number of bunches, the M treatment had the lowest, and the R treatment exhibited intermediate values. Overall, the average grapevine yield ranged from 7.25 to 13.7 t ha−1, corresponding to 52–98 hL ha−1 (with 4000 vines ha−1, 140 kg hL−1). This level of production may be accepted for Protected Designations of Origin that limit grapevine yield to 40 or 60 hL ha−1, but it could be a limitation for Protected Geographical Indications, which permit 90 hL ha−1, or unlabeled productions without yield limitations. Given the Mediterranean climate context, with rising frequencies of dry winters due to climate change, termination involving soil tillage appears to be the least risky strategy to preserve grapevine vigor and production while improving soil-based ecosystem functions. However, this might be contingent on the targeted yield and wine valuation
How collectively integrated are ecological communities?
No full textInternational audienceBeyond abiotic conditions, do population dynamics mostly depend on a species' direct predators, preys and conspecifics? Or can indirect feedback that ripples across the whole community be equally important? Determining where ecological communities sit on the spectrum between these two characterizations requires a metric able to capture the difference between them. Here we show that the spectral radius of a community's interaction matrix provides such a metric, thus a measure of ecological collectivity, which is accessible from imperfect knowledge of biotic interactions and related to observable signatures. This measure of collectivity integrates existing approaches to complexity, interaction structure and indirect interactions. Our work thus provides an original perspective on the question of to what degree communities are more than loose collections of species or simple interaction motifs and explains when pragmatic reductionist approaches ought to suffice or fail when applied to ecological communities
Fusion of BERT embeddings and elongation-driven features
No full textInternational audienceElongated words such as "Wiiiiiin" or "allloooo" are common in oral communication and are often used to emphasize or exaggerate the hidden message of the root word. While elongated words are rarely found in written languages and dictionaries, they are prevalent in social media networks. Considering elongation in sentiment analysis can provide valuable insights into user sentiments. In this article, we analyze the impact of elongation on sentiment classification, along with an in-depth study of lexical forms of elongation. We propose a method to enhance sentiment classification accuracy by incorporating elongation-based features using BERT (bidirectional encoder representations from transformers) approaches. Experimental results conducted on Twitter data demonstrate that our model achieves an average accuracy of 87% through 10-fold cross-validation experiments
Approche multidisciplinaire vers une valorisation des biomasses locales en bioproduits durables : matériaux et énergie
No full textWood and other ligneous biomass constitute an abundant and worldwide available resource that can play a major role in reaching today's environmental challenges. This renewable resource is essential to the development of a bio-based economy as part of the ecological transition, as it is a substitute for petroleum-based resources. There are many ways in which it can be used, notably in the fields of energy production, construction materials, the formulation of new chemicals or molecules similar to those produced by petrochemicals, and the production of new sustainable materials with low environmental impact.The common thread running through the various research activities presented in this manuscript is the valorization of lignocellulosic biomass for green chemistry applications. The biochemical composition of extractives compounds, their diversity and variability, and their value-adding potential in the field of wood preservation represent the most part of my researches.With a global vision based on a "multidisciplinary approach" to the valorization of ligneous biomasses into sustainable bioproducts, the three main following areas studied are developed:- Thermal and thermochemical modification processes for wood and woody biomasses;- Biochemical characterizations of biomasses for use in sustainable materials and bioproducts;- Evaluation of the impact of the silvicultural practices (such as agroforestry) on the wood chemical composition.All this work is primarily the result of different environments (scientific and geographical), various collaborations, relationships and sharing. It should be pointed out that this work has always been oriented towards applied research, encouraged by national and international projects responding to very specific development needs.Le bois et toute autre biomasse ligneuse constituent une ressource abondante et disponible à l’échelle mondiale qui peut jouer un rôle majeur en réponse aux enjeux environnementaux actuels et de demain. Cette ressource renouvelable est essentielle pour la mise en place d’une économie biosourcée dans le cadre de la transition écologique, du fait qu’elle constitue un produit de substitution au regard des ressources pétrosourcées. Les voies de valorisations sont nombreuses et peuvent se faire notamment dans les domaines de la production d’énergie, des matériaux de construction, de la formulation de molécules chimiques nouvelles ou semblables à celles issues de la pétrochimie et dans la production de nouveaux matériaux durables et à faible impact environnemental.Le point commun des différentes activités de recherches présentées dans ce mémoire d’HDR concerne la valorisation de la biomasse ligno-cellulosique pour des applications dans le domaine de la chimie verte. La composition biochimique des composés extractibles, leur diversité et leur variabilité, ainsi que leur potentiel de valorisation dans le domaine de la préservation des bois représente la grande majorité de mes recherches.Avec une vision globale axée sur une « approche multidisciplinaire » de la valorisation des biomasses ligneuses en bioproduits durables, les trois principaux axes étudiés sont :- Les procédés de modifications thermiques et thermochimiques du bois et des biomasses ligneuses ;- Les caractérisations biochimiques des biomasses en vue de leur valorisation en matériaux durables et bioproduits ;- L’impact du mode sylvicole (cas de l’agroforesterie) sur la composition chimique du bois.L’ensemble de ce travail est avant tout le fruit de différents environnements (scientifiques et géographiques), de diverses collaborations, de rencontres et de partages. Il convient préciser que ces travaux ont toujours été orientés vers une recherche appliquée, encouragée par des projets nationaux et internationaux répondant à des besoins de développement bien spécifiques
A new genus of alphasatellites associated with banana bunchy top virus in Southeast Asia
No full textInternational audienceAutonomously replicating alphasatellites (family Alphasatellitidae) are frequently associated with plant single-stranded (ss)DNA viruses of the families Geminiviridae, Metaxyviridae, and Nanoviridae. Alphasatellites encode a single replication-initiator protein (Rep) similar to Rep proteins of helper viruses and depend on helper viruses for encapsidation, movement, and transmission. Costs versus benefits of alphasatellite-helper virus association are poorly understood. Our surveys in Southeast Asia (SEA) for wild and cultivated banana plants infected with banana bunchy top virus (BBTV, Nanoviridae) and Illumina sequencing reconstruction of their viromes revealed, in addition to a six-component BBTV genome, one to three distinct alphasatellites present in sixteen of twenty-four BBTV-infected plants. Comparative nucleotide and Rep protein sequence analyses classified these alphasatellites into four distinct species: two known species falling into the genus Muscarsatellite (subfamily Petromoalphasatellitinae) previously identified in SEA and two novel species falling into the tentative genus Banaphisatellite (subfamily Nanoalphasatellitinae) so far containing a single species recently identified in Africa. The banaphisatellites were found to be most related to members of the genus Fabenesatellite of subfamily Nanoalphasatellitinae and the genus Gosmusatellite of subfamily Geminialphasatellitinae, both infecting dicots. This suggests a dicot origin of banaphisatellites that got independently associated with distinct strains of monocot-infecting BBTV in Africa and SEA. Analysis of conserved sequence motifs in the common regions driving replication and gene expression of alphasatellites and BBTV strains revealed both differences and similarities, pointing at their ongoing co-evolution. An impact of alphasatellites on BBTV infection and evasion of RNA interference-based antiviral defences was evaluated by measuring relative abundance of BBTV genome components and alphasatellites and by profiling BBTV- and alphasatellite-derived small interfering RNAs. Taken together, our findings shed new light on the provenance of alphasatellites, their co-evolution with helper viruses, and potential mutual benefits of their association