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A modelling approach to disentangle DOC release processes from riparian wetlands
No full textInternational audienceRelease of dissolved organic carbon (DOC) from soils into pore waters can occur via three distinct processes: (i) microbial decomposition of soil organic matter, producing soluble organic molecules; (ii) desorption of DOC from soil mineral surfaces, such as oxyhydroxides and clays, driven by increasing pH in pore waters and (iii) reduction of ferric iron in waterlogged soils, leading to the dissolution of amorphous Fe(III) oxyhydroxides that were previously coprecipitated with dissolved organic matter. Once released into pore waters, DOC can either be mineralised or exported to surface waters.Riparian wetlands are important sources of organic matter and sites where all three DOC release mechanisms may occur. DOC release via microbial decomposition (process i) is typically associated with a rapidly cycling DOC pool that fuels microbial mineralisation, whereas desorption and reductive dissolution processes (ii and iii) are often linked to DOC mobilisation and export of a potentially more stable, mineral-associated pool of soil organic matter. Despite their importance, the relative contributions of these processes and their controlling factors remain incompletely understood. Improved understanding of these mechanisms may provide insight into the extent to which these processes are likely to influence the long-term carbon storage capacity of wetland soils.Against this background, we propose and demonstrate a modelling approach to disentangle the processes and drivers of seasonal DOC mobilisation in riparian pore waters of the Kervidy-Naizin Critical Zone Observatory in western France. First, a principal component analysis was applied to weekly to biweekly measurements (period from November 2022 until May 2023 and 17 sites) of pH, nitrate, DOC, soluble reactive phosphorus, ferrous iron, five variables describing dissolved organic matter composition based on fluorescence properties, and hydrological variables. Scores of the first two principal components - interpreted as proxies for DOC desorption and reductive dissolution of coprecipitates - were extracted. Second, these component scores, together with two additional variables assumed to represent lateral DOC leaching and microbial decomposition of soil organic matter, respectively, were used as predictors in a generalized additive model (GAM) of DOC concentrations. Third, the GAM was used to quantify the relative contributions of the four processes to DOC increases.Our analysis suggests that desorption was the dominant process responsible for DOC release during winter and spring in the studied riparian zones of the Kervidy-Naizin catchment. These results demonstrate that disentangling the processes contributing to seasonal DOC mobilisation in riparian soils - such as pH driven desorption and reductive dissolution of coprecipitates - is feasible using a combined multivariate and additive modelling approach. To further improve the quantification of individual process contributions, additional measures of DOC quality, for example derived from FT-ICR MS, are likely to be beneficial
Un partage d’expérience autour de la pratique de l’interdisciplinarité sur les feux : le projet EcoSoFI (2022-2024)
No full textInternational audienceLes collaborations inter/transdisciplinaires autour de la compréhension des feux et de leur gestion sont plébiscitées, mais leur mise en œuvre ne va pas pour autant de soi. A partir du partage d’expériences de plusieurs scientifiques et gestionnaires, le présent article restitue la démarche que nous avons adoptée pour comprendre ces difficultés ; et tire quelques constats et propositions. Onconstate notamment la dominance des sciences biophysiques et le poids de la modélisation dans les interfaces entre recherche et gestion. Au sein des SHS, on observe également des partitions entre disciplines et sous-disciplines, ainsi qu’une « interdisciplinarité inachevée » dans l’analyse des changements de régimes de feux. La spécialisation disciplinaire a conduit à une autonomisation du questionnement et des méthodes, qui ne sont plus explicitées ni interrogées au regard des autres approches et du terrain. Nos propositions consistent à remettre en question les catégories implicites concernant les pratiques et les savoirs liés aux feux et à définir des protocoles de recherche permettant des problématisations communes à partir d’études de cas localisées et « concrètes »
Nutrition and health aspects of milk and milk products
No full textInternational audienceThe present chapter aims to give an overview of the worldwide dairy products and of their nutritional quality. The importance of their food structure on digestion is examined, before reporting their health properties, as indicated by meta-analyses of epidemiological studies. Dairy products, mainly originating from bovine milk, are a good source of high-quality proteins, specific lipids (polar, short chain, conjugated), micronutrients (calcium, iodine, phosphorus, vitamins B2 and B12, etc.), and eventually of probiotics and their deriving metabolites. The dairy product structure affects the protein and lipid digestion fate, with potential metabolic consequences. Dairy products appear to have health effects either beneficial (obesity, type II diabetes, hip fracture) or neutral (cardiovascular diseases), but may be at risk for prostate cancer for high consumers. Overall, dairy products are an important food group, supplying essential nutrients and eventually probiotics, with potential beneficial health effects as long as consumed at the recommended levels (2–3 portions/day)
Compréhension territoriale de la circularité du système agroalimentaire : flux énergétiques et azotés de deux régions d'élevage en Bretagne (France)
No full textInternational audienceContextRegions of intensive farming are often associated with large nutrient surpluses emitted from agri-food systems (AFS). Agricultural transitions require reaching a balance between the roles of livestock systems in producing high-quality protein and organic fertilizers, while mitigating pollutant emissions. However, effects of the relative percentages of ruminants and monogastric animals in regions with high livestock density on their food production and environmental impacts remain unexplored. While most research on nutrient flows in AFS focuses mainly on large scales (e.g. continents, countries), the territorial scale remains underexplored.ObjectiveThis study aimed to develop an integrated, down-scaled (NUTS 3) assessment framework to analyze nitrogen (N) and energy flows in two territories with differing compositions of ruminants and monogastric animals.MethodsUsing material flow analysis based on public data, we examined two neighboring territories in Brittany, France. We assessed their environmental impacts, N flows, and energy functioning.Results and conclusionsThe two territories imported 38% and 62% of N in feed, respectively, producing enough animal products to meet 9–13 times their local need for animal-based food. The results suggest that the area of external agricultural land required for producing feed imports is as large as the used agricultural area in the territory. Energy from biogas production represented 20% of the total energy input of the AFS. The territory with a more balanced share of ruminants and monogastric animals had higher livestock N conversion efficiency (37% vs. 30%) but lower total N self-sufficiency (21% vs. 12%) than the more ruminant-dominant territory.SignificanceThese results provide novel insights into environmental impacts of multiple combinations of ruminant and monogastric animal systems in similar territories. Such results could be useful for local policymakers and AFS stakeholders to help them understand the impacts of different livestock combinations on N and energy flows in their territory. The study also provides a framework for subnational-scale assessments, which are not well represented in public data. This framework is a key first step to facilitate the transition toward more sustainable AFS
Quelles configurations de travail en élevage laitier breton pour la transition et la collaboration agroécologiques ?
No full textInternational audienceForms of inter-farm cooperation that have existed since the post-war period are now being reorganized with the development of agroecological practices, in order to co-produce and co-manage the strategic resources necessary for this transition. Farm machinery cooperatives (Cuma), as well as experience sharing and collective training groups, are particularly active in dairy farming, especially on low-input grassland farms. However, dairy farming remains the agricultural sector with the highest workload per worker, which raises questions about the ability of farmers to find the time to participate in these collaborative activities.In this context, a key question emerges: Are there work configurations that are conducive to both the grassland orientation of dairy farms and involvement in collaborations that facilitate the management of grassland systems? To answer this question, exploratory interdisciplinary research combining animal science and sociology was conducted in 2022 in Brittany, based on interviews with around 30 dairy farmers.After clarifying the approach and survey method, this chapter first analyzes the role of farm scale—understood as the ratio between economic scale and number of unit of work —in grassland management. It then examines other factors influencing involvement in inter-farm collaborations. Finally, it proposes avenues for further research and recommendations for public policy and extension.Des formes de collaboration inter‑exploitations présentes depuis l’après‑guerre se recomposent aujourd’hui sous l’effet du développement de pratiques agroécologiques, afin de coproduire et de cogérer les ressources stratégiques nécessaires à cette transition. Les coopératives d’utilisation de matériel agricole (Cuma), ainsi que les groupes d’échanges et de formation collective entre pairs, sont particulièrement mobilisés en élevage laitier, notamment dans les exploitations herbagères économes en intrants. Toutefois, l’élevage laitier demeure le secteur agricole où la charge de travail par actif est la plus élevée, ce qui interroge la capacité des éleveurs à dégager du temps pour participer à ces activités collaboratives.Dans ce contexte, une question centrale émerge : Existe‑t‑il des configurations de travail favorables à la fois à l’orientation herbagère des élevages bovins laitiers et à l’implication dans les collaborations facilitant la gestion de systèmes herbagers ? Pour y répondre, une recherche exploratoire interdisciplinaire associant zootechnie et sociologie a été menée en 2022 en Bretagne, reposant sur des entretiens avec une trentaine d’éleveurs laitiers.Après avoir précisé l’approche et la méthode d’enquête, ce chapitre analyse d’abord le rôle de l’échelle de l’exploitation — entendue comme le ratio entre dimension économique et nombre d’actifs — dans l’orientation herbagère. Il examine ensuite les autres facteurs conditionnant l’engagement dans les collaborations inter‑exploitations. Enfin, il propose des pistes de recherche complémentaires ainsi que des orientations pour l’action publique et le développement
Estimation of milk yield and lambs’ growth during the suckling period for the Sicilo-Sarde breed in Tunisia
No full textInternational audienceThe aim of this study was to estimate the suckling milk yield (SMY) of the Sicilo-Sarde ewes during different length of suckling periods and to evaluate its impact on the lambs' growth. The SMY was estimated by the method of weighing lambs before and after suckling. Eight controls were carried out on a sample of ten ewes aged 3.90 +/- 0.50 years, suckling single male lambs. The measurement of SMY was conducted weekly until weaning. The daily and total SMY were 1.33 +/- 0.21 kg/d and 79.62 +/- 12.58 kg, respectively for 60 days suckling period. The SMY was estimated at 39.30 +/- 7.20 kg and 61.31 +/- 10.67 kg for 30 and 45 days of suckling, respectively. Lamb weights were 11.31, 14.73 and 18.24 kg respectively at 30, 45 and 60 days of age. The average daily gain (ADG) calculated between the ages of 10 and 30 days (ADG(10-30)), and 30 and 60 days (ADG(30-60)) were 222 +/- 46 and 231 +/- 45 g/d, respectively. Lambs weight at 30 days and ADG(10-30) were the most correlated indicators with all SMY (0.71 <= r <= 0.80; P < 0.05). The SMY levels of ewes and the lambs' growth obtained are satisfactory and indicate an interesting dairy potential of this breed. Weaning lambs at 45 days increases the marketed milk, without negatively affecting the lambs' growth
A pilot study testing a continuous glucose monitoring sensor in lean growing pigs fed contrasting diets, to document nocturnal and diurnal glycemic excursions as well as their relationships
No full textInternational audienceTimely non-invasive monitoring of physiology is an emerging field in farm animal research, providing new insights on how animals adapt to environmental challenges and how we can manage performance, health, and welfare. In this study, continuous glucose monitoring (CGM) sensors were used to document glycemic excursions in lean growing pigs. Crossbred pigs (49 ± 3 kg, n = 8) were fitted with CGM sensors and indwelling venous catheters, and followed in a five-day feeding trial involving a progressive change in diet composition from high starch (HS) to high fat (HF). At days 2 and 5, time-series blood samples were collected after the first morning meal and used for time-matched chemistry analysis. During the postprandial period, the average CGM reading was higher (P = 0.01) on the HS diet than on the HF diet, primarily due to the fact that maximum glucose value at peak was higher (P < 0.05) after consuming the HS test meal than the HF meal. During night when the pigs had no access to feed, the period with glucose concentrations above baseline was twice longer (P < 0.05) with the HS diet than the HF diet. Various CGM metrics at night were or tended to be correlated with postprandial CGM metrics (P < 0.10). Finally, large inter-individual variability was observed in glycemic metrics, larger during day than during the night (P < 0.05). To conclude, this study highlights the importance of considering night-time events to inform about animal physiology and further improve precision feeding in pigs
Gestion de sites protégés : concrétiser le croisement de compétences
No full textInternational audienceCet appel à communications interroge les moyens de « faire face à une montée des thématiques et savoir-faire techniques, scientifiques, écologiques au détriment d’une appréhension plus globale, plus complexe des territoires et de leurs singularités ». Ayant été confrontés à ces difficultés, sur des sites protégés d’un point de vue patrimonial et environnemental lors de partenariats entre recherche et maitrise d’œuvre en paysage, il nous a semblé utile d’en examiner les causes. Nous avons ici analysé les comptes-rendus de réunions de travail entre plusieurs bureaux d’étude - milieux aquatiques, hydraulique, paysage -, à propos d’une mission de diagnostic, puis d’élaboration de scénarios de paysage et de gestion afférente, sur un site majeur à Angers : l’Étang St Nicolas, qui représente trente hectares pour le plan d’eau, et une centaine d’hectares pour les parcs attenants. Ces huit heures d’échange, réparties sur trois réunions de travail en avril 2023, juillet 2023 et mai 2024, représentent un matériau modeste quantitativement, mais riche d’enseignements. Il montre que la collaboration se heurte à des perceptions différentes inhérentes aux cultures professionnelles. Celles-ci s’expriment dans la posture de maitrise d’œuvre en réponse au commanditaire (technique et réglementaire pour l’un, prospective pour l’autre), dans la focale d’analyse (thématique pour l’un, inter-thématiques pour l’autre), dans la relation de l’humain au site (menace pour l’un, partenaire pour l’autre). Il ne s’agit pas tant d’opposer les approches ou de les lisser, mais (1) de pouvoir nommer ces divergences au démarrage de la collaboration, et (2) de lever d’éventuels contresens sur la méthodologie de travail. Dans ce cas précis, un rapport de force était constitué, du fait du rôle de mandataire assigné au bureau d’étude en hydrobiologie. Il y a ainsi un enjeu fort de communication vis-à-vis des maitrises d’ouvrages pour que la nécessité d’une approche non sectorielle, qui est le propre de l’approche paysagère, soit reconnue comme socle de conduite du projet de territoire
When rhizosphere complexity is too important for constraining into a single causality pattern: A causal inference methodology
No full textInternational audienceStructural Equation Modeling is used in ecological studies to confirm pre-assumed multivariate causal relationships. However, the rhizosphere is a complex environment, and knowledge is not sufficiently consistent to propose unambiguous causal relationships to be tested. Using a Latent Variable Structural Equation Modeling framework, that aims to build and explore different causality patterns in rhizosphere environments, we designed an exploratory approach to detect causality patterns that are worth being investigated a posteriori and contribute to rhizosphere knowledge and applications. Grounded in statistical methods, exploration of the “causal space” is applicable to prioritize rhizosphere causality patterns that worth to be tested. Application of our framework to field studies is discussed. The term causal space is debated as a pioneer concept for causal inference in the rhizosphere
A pan-European map of shallow aquifer transmissivity in crystalline headwater catchments inferred from wetland and stream networks
No full textInternational audienceGroundwater systems in headwater catchments are poorly represented at continental scales due to model resolution constraints and limited observations available to characterize the wide diversity of catchments. Yet, low-order headwater streams accounting for a major fraction of the global river network. This is particularly true in upland crystalline bedrock regions with dense drainage networks, where the lithology has long been considered impermeable, without aquifers, and thus has received limited hydrogeological attention.We present a new continental-scale assessment of effective transmissivity for 3,333 European crystalline headwater catchments (median ≈35 km²), underlain by unconfined, shallow hard-rock aquifers where subsurface-surface interactions strongly shape hydrological connectivity. Catchments including dams, glaciers, and extensive permafrost were excluded.The methodology represents lateral hillslope groundwater flow within shallow subsurface systems, capturing the spatial patterns of saturated areas at the catchment scale. This framework of physically based groundwater flow models enables steady-state simulation of perennial surface water networks (springs, streams, wetlands), whose length and structure are highly sensitive to shallow aquifer transmissivity (Abhervé et al., 2023). Transmissivity was inferred through optimization of simulated seepage areas against observed wetland and stream networks, using constant recharge estimates from an independent land surface model and assuming dominant superficial subsurface flow in the upper 50 m. Across all calibrated models, the simulated networks closely replicate the available European-scale extended wetland ecosystem layer and stream network from the EU-Hydro database.Estimated transmissivity ranges from 10⁻⁸ to 10⁻² m² s⁻¹ (mean ≈10⁻⁴ m² s⁻¹), with pronounced spatial variability across geological provinces, massifs, or regions sharing similar tectonic framework legacies. The broad transmissivity range demonstrates the method’s sensitivity and its ability to resolve catchment-scale effective hydraulic properties across diverse climatic, topographic, and geological contexts. Values are consistent with textbook estimates for the studied lithologies and with hydraulic test data (pumping and slug tests) from regional or global datasets. Both measurements and estimates follow a log-normal distribution. Hydraulic conductivity was also derived from transmissivity using independent aquifer thickness datasets, including global depth-to-bedrock and regolith thickness maps.Our results provide the first EUropean crystalline bedRock hydrogeological HEADwater map of transmissivitY (EURHEADY), explicitly accounting for groundwater flows at the catchment scale. All calibrated simulations are provided as a georeferenced dataset, complemented by physiographic, climatic, hydrologic, pedologic, geologic, hydrogeologic, and anthropogenic attributes. This approach addresses a critical gap in estimating hydrogeological properties, a long-standing challenge for the critical zone community, and opens new opportunities for large-scale hydro(geo)logical modeling with improved representation of groundwater contributions.Reference:Abhervé, R., Roques, C., Gauvain, A., Longuevergne, L., Louaisil, S., Aquilina, L., & de Dreuzy, J. (2023). Calibration of groundwater seepage against the spatial distribution of the stream network to assess catchment-scale hydraulic properties. Hydrology and Earth System Sciences, 27(17), 3221–3239. https://doi.org/10.5194/hess-27-3221-202