HAL Portal AgroParisTech
Not a member yet
73916 research outputs found
Sort by
Accords commerciaux et pêche durable
No full textInternational audienceThis study examines the impact of trade agreements and their specific provisions on the sustainability of marine fisheries resources. Using global data on the Mean Trophic Level (MTL) between 1950 and 2018 and a comprehensive dataset of environmental provisions from trade agreements signed between 1947 and 2018, we estimate the impact on the MTL of signing (i) a free trade agreement and (ii) a free trade agreement including fishery-related provisions. To address potential endogeneity problems associated with fisheries-related provisions, we use a difference-in-differences (DID) propensity score matching method. Our results show that while trade agreements tend to negatively impact the MTL, including fisheries-related provisions offsets this negative impact among signatory countries. By examining the potential mechanisms underlying this result, we are able to temper the optimistic findings in the existing literature on the beneficial environmental outcomes of environmental provisions. Our findings suggest that these provisions do not foster the adoption of more effective resource management practices. Instead, they appear to reduce trade opportunities, which is contrary to the objective of trade creation in trade agreements.Cette étude examine l'impact des accords commerciaux et de leurs dispositions spécifiques sur la durabilité des ressources halieutiques marines. À partir de données mondiales sur le niveau trophique moyen (MTL) entre 1950 et 2018 et d'un ensemble complet de données sur les dispositions environnementales des accords commerciaux signés entre 1947 et 2018, nous estimons l'impact sur le MTL de la signature (i) d'un accord de libre-échange et (ii) d'un accord de libre-échange comprenant des dispositions relatives à la pêche. Pour remédier aux problèmes d'endogénéité potentiels liés aux dispositions relatives à la pêche, nous utilisons une méthode d'appariement des scores de propension à la différence dans les différences (DID). Nos résultats montrent que si les accords commerciaux ont tendance à avoir un impact négatif sur le MTL, l'inclusion de dispositions relatives à la pêche compense cet impact négatif parmi les pays signataires. En examinant les mécanismes potentiels qui sous-tendent ce résultat, nous sommes en mesure de tempérer les conclusions optimistes de la littérature existante sur les effets bénéfiques des dispositions environnementales. Nos conclusions suggèrent que ces dispositions ne favorisent pas l'adoption de pratiques de gestion des ressources plus efficaces. Au contraire, elles semblent réduire les opportunités commerciales, ce qui est contraire à l'objectif de création d'échanges commerciaux dans les accords commerciaux
Optimizing the Viability of Interacting Systems with Evolutionary Algorithms
No full textInternational audienceViability theory studies the behavior of dynamical systems, with the aim of keeping them viable, or in other terms, keep their trajectories within desired constraints in the state space. Finding strategies to keep a dynamical system viable is already a challenge for optimization algorithms, but this task becomes even harder for multi-agent systems, where agents’ individual decision can influence the dynamics of the whole system. In this paper, we consider a multi-agent dynamic system and introduce an evolutionary approach for optimizing agents’ interaction behaviour, delimited by some a priori agreements, in the form of a set of commitments, with the objective of keeping the system viable. This approach is tested on the case-study of a collective project grouping several agritouristic activities on a shared place. Experimental results show that it is possible to find a set of agents’ commitments that can maintain system viability, supporting the proposed framework’s effectiveness
Seasonal divergence in the sensitivity of carbon and water fluxes to climate variability in terrestrial ecosystems
No full textInternational audienceUnderstanding vegetation sensitivity to hydroclimate factors, especially how carbon and water cycles respond toclimate change, is crucial for assessing ecosystem vulnerability. However, the seasonal sensitivity of carbon andwater fluxes to temperature, radiation, soil water content, and vapor pressure deficit across diverse biomes andclimates remains unclear. Here, we use 196 eddy covariance observations from sensor networks distributedglobally, along with daily estimates from Earth System Models (ESMs), to quantify the seasonal sensitivity ofdaily gross primary productivity (GPP), ecosystem respiration (RE), net ecosystem productivity (NEP), andevapotranspiration (ET) to various hydroclimate factors. Our ridge regression analysis reveals seasonal variationsin the sensitivity of carbon and water fluxes to hydroclimate factors across globally distributed flux sites. GPPand NEP are most sensitive to air temperature (TA) in spring, but to radiation (RAD) in summer, autumn andwinter. RE consistently exhibits positive sensitivity to TA across all seasons, while ET shows the highest sensi-tivity to RAD throughout the year. Although energy-related factors like TA and RAD dominate the influence oncarbon and water fluxes at sub-seasonal scales, soil water content (SWC) and vapor pressure deficit (VPD)become increasingly important during summer, particularly in drylands. At sites with long-term measurements,we identified a significant upward trend in the sensitivity of summer GPP to SWC with 0.005 ± 0.002 per year,suggesting that terrestrial ecosystems are becoming more constrained by water stress during summer. Comparedto observations, ESMs generally overestimate the sensitivity of GPP to SWC and VPD, while underestimate thesensitivity to RAD and TA during summer. Our findings enhanced the understanding of the seasonal response ofecosystem carbon and water cycles to hydroclimate factors, offering insights into ecosystem function underfuture climate change
Food from synthetic cooking has no relationship with the fiction food that is discussed in the movie Soylent green
No full textInternational audienceThe concept of "synthetic food", produced from ingredients that are pure compounds rather than animal or plant tissues, has sometimes been compared to the dystopian food depicted in the film Soylent Green. This analogy is misleading: synthetic food is not derived from the human bodies. Synthetic cooking, and the associated culinary trend called "note by note cuisine", expand the technical and art possibilities of cooking by enabling precise control over flavor and nutritional content. This article examines the historical roots of resistance to new culinary techniques, to better understand the skepticism surrounding synthetic food. Finally, strategies to improve public acceptance of synthetic cooking -emphasizing transparency, sustainability and education -are proposed.
Generic crop rotation pattern-matching algorithm revealed dominant rotational systems for France
No full textInternational audienceCrop rotations remain poorly documented at large spatial scale, despite their central role in agroecosystem sustainability. We present a generic pattern-matching algorithm to infer crop rotations from annual crop sequence datasets, such as those derived from the European Land Parcel Identification System, with minimal crop aggregation. This method identifies field-level rotations, quantifies their flexibility, and enables spatially-explicit assessment of dominant crop and grasslands rotational systems at various spatial and thematic levels. Applied to mainland France, the approach identified crop rotations on 90% of arable area, with four-year rotations -typically including two to three years of flexible crops-being the most common. Nationally, the top 20 rotations accounted for 30% of arable land, while the top 52 covered 50%. At the agricultural district scale, we distinguished 25 dominant rotational systems grouped into eight categories, including (i) maize grain monocropping, (ii) maize grain -winter wheat rotations, (iii) sunflower -winter wheat rotations, (iv) grass-based systems, (v) maize silage -winter wheat rotations, (vi) winter wheat -barley -rapeseed rotations, (vii) root crop-based rotations, and (viii) specialized production. At national scale, organic rotations were longer and more flexible than conventional ones. Rotations of larger farms were longer and temporally more diverse than smaller ones, but showed lower spatial diversity. This scalable, data-driven approach offers new insights into crop rotation patterns and their spatial variability. It can support the large-scale assessment of agroecosystems with quantitative evidences on dominant rotations, but also help at tracking and characterizing localized rotational innovations
The evolution of drought characteristics in semi-arid Africa over the last four decades
No full textInternational audiencetudy regionSemi-arid Africa, covering six subregions: the Mediterranean (MED), Sahel, North Eastern Africa (NEAF), South Eastern Africa (SEAF), Southern Africa (SAF), and Madagascar (MDG).Study focusWe analyse drought duration, intensity, and severity from 1979 to 2024 across semi-arid Africa. Using Climate Prediction Center (CPC, 0.5°) precipitation and temperature, we compute the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). Trends are detected with the Mann–Kendall test and Theil–Sen slope estimator. Short-term droughts (3–6 months), strongly influenced by temperature variability, are distinguished from 12-month events driven by cumulative hydrological deficits.New hydrological insightsThree drought episodes emerge: the early 1990s, early 2000s, and the recent period beginning in 2022. Long time-scale indices (SPI-12, SPEI-12) capture the most persistent droughts, whereas short time-scale indices (SPEI-3, SPEI-6) reveal intense temperature-driven episodes. In MED, only 7–25 % of grid cells show significant SPI trends in duration, severity, and intensity, but up to 75 % exhibit drought intensification with SPEI, underscoring strong temperature sensitivity. Across NEAF, SEAF, SAF, and MDG, 25–55 % of pixels show significant increases in drought duration (up to +3 months per decade), severity (+3 units per decade), and intensity (+0.5 units per decade). Parts of the western Sahel and southern Madagascar display decreasing trends. Overall, the study delivers a continent-wide assessment of drought evolution and identifies hotspots where intensifying drought threatens water resources and food security
Stepwise recombination suppression around the mating-type locus associated with a diploid-like life cycle in Schizothecium fungi
No full textInternational audienceRecombination suppression often evolves around sex-determining loci and extends stepwise, resulting in adjacent regions with different levels of divergence between sex chromosomes, called evolutionary strata. In Ascomycota fungi, evolutionary strata around the mating-type (MAT) locus have been reported only in pseudo-homothallic species, which have a diploid-like life cycle with mycelia carrying nuclei of both mating types. In contrast, no recombination suppression has been observed in heterothallic fungi, where colonies contain only a single mating type. Here, we investigated the evolution of recombination suppression in a clade of dung fungi encompassing 16 pseudo-homothallic and three heterothallic sibling species from the Schizothecium genus (Ascomycota, Sordariales). The analysis of genetic divergence based on genome sequencing indicated recombination suppression around the MAT locus in all 13 pseudo-homothallic species examined. The nonrecombining region ranged from 600 kb to 1.6 Mb and harbored multiple evolutionary strata, varying in size and number among species. The clustering of alleles according to mating type in gene genealogies, the high linkage disequilibrium, and an inversion in one species supported the lack of recombination in the MAT-proximal region in pseudo-homothallic species. The overall lack of trans-specific polymorphism suggested multiple independent recombination suppression events or occasional recombination/genic conversion. In heterothallic species, progeny analyses showed that recombination occurs in regions at physical distances from the MAT locus similar to those in which it is lacking in the pseudo-homothallic species. We thus revealed here multiple, likely independent evolutionary strata, associated with an extended diploid-like stage in Schizothecium fungi
Method: Modelling resource acquisition and allocation – extension and calibration of a cow model to a sheep
No full textInternational audienceSimulation models are suitable to investigate how complex systems respond to changes. This is of particular interest regarding animal feed efficiency as this trait must be evaluated throughout the entire lifetime and thus is affected by trade-offs between physiological functions. The aim was to extend and calibrate the dynamic, mechanistic simulation model “Acquisition and Allocation” (AQAL) from dairy cows to reproductive ewes. This model was originally developed for investigating the effects of resource acquisition and allocation potentials on feed efficiency but also allows investigation of trade-offs between life functions. The model represents an individual female from birth to death or herd exit and uses four input parameters to describe the resource acquisition ability and allocation potential. The obtained energy is split between life functions such as maintenance, growth, reproduction and lactation. By including reproductive management rules, it allows for shifts between physiological stages, which then feedback and affect the current acquisition ability and resource allocation. To adapt the model to a reproductive ewe, we have included a litter size effect, an acquisition capacity linked to gestation, and a seasonal conception probability. The litter size is influenced by the proportion of fat in empty body weight at conception, and it affects the acquisition linked to gestation, the allocation to gestation and the allocation to lactation. We also incorporated the energetic costs of the gravid uterus depending on litter size. We use three different acquisition-allocation profiles to test the consistency of the litter size effect. We show that the model simulates consistent lifetime trajectories of reproductive ewes and that the effect of litter size adequately reflects the demands of increased litter size within the different acquisition/allocation profiles
The Global Spectra-Trait Initiative: A database of paired leaf spectroscopy and functional traits associated with leaf photosynthetic capacity
No full textInternational audienceAccurate assessment of leaf functional traits is crucial for a diverse range of applications from crop phenotyping to parameterizing global climate models. Leaf reflectance spectroscopy offers a promising avenue to advance ecological and agricultural research by complementing traditional, time-consuming gas exchange measurements. However, the development of robust hyperspectral models for predicting leaf photosynthetic capacity and associated traits from reflectance data has been hindered by limited data availability across species and environments. Here we introduce the Global Spectra-Trait Initiative (GSTI), a collaborative repository of paired leaf hyperspectral and gas exchange measurements from diverse ecosystems. The GSTI repository currently encompasses over 7500 observations from 397 species and 41 sites gathered from 36 published and unpublished studies, thereby offering a key resource for developing and validating hyperspectral models of leaf photosynthetic capacity. The GSTI database is developed on GitHub (https://github.com/plantphys/gsti, last access: 4 January 2026) and published to ESS-DIVE https://doi.org/10.15485/2530733, Lamour et al., 2025). It includes gas exchange data, derived photosynthetic parameters, and key leaf traits often associated with traditional gas exchange measurements such as leaf mass per area and leaf elemental composition. By providing a standardized repository for data sharing and analysis, we present a critical step towards creating hyperspectral models for predicting photosynthetic traits and associated leaf traits for terrestrial plants