Portail HAL de l'OFB
Not a member yet
3699 research outputs found
Sort by
Spatio-temporal dynamics of attacks around deaths of wolves: a statistical assessment of lethal control efficiency in France
No full textInternational audienceThe lethal control of large carnivores is criticized regarding its efficiency to prevent hotspots of attacks on livestock. Previous studies, mainly focused on North America, provided mixed results. We evaluated the effects of wolf lethal removals on the distribution of attack intensities in the French Alps between 2011 and 2020, using a Before After Control‐Impact approach with retrospective data. We built an original framework combining both continuous spatial and temporal scales and a 3D kernel estimation. We compared the attack intensities observed before and after the legal killings of wolves over a period of 90 days and a range of 10 km, and with control situations where no removal occurred. The analysis was corrected for the presence of livestock. A moderate decrease in attack intensity was the most common outcome after the lethal removal of a single wolf. This reduction was greatly amplified when removing two or three wolves. The scale of analysis also modulated this general pattern, with decreases being generally amplified at a small spatio-temporal range. Contextual factors (e.g., geographical or seasonal variations) could also lead to deviations from this general pattern. Overall, between 2011 and 2020, lethal control of wolves in France generally contributed to reducing livestock attacks, but mainly locally and to a minor extent. Our results highlight the importance of accounting for scale in such assessments and suggest that the evaluation of the effectiveness of lethal removals in reducing livestock predation might be more relevant in a local context. As a next step, we recommend to move forward from patterns to mechanisms by linking the effects of lethal control on wolves to their effects on attacks through analysis of fine-scaled data on wolves and livestock
Inferring Endozoochory From Ingestion to Germination Through Biological Filters: Brown Bear Feces as a Case Study
No full textInternational audienceDiaspore (e.g., seed and spore) dispersal is recognized as a key mechanism in plant dynamics, including endozoochory, which can be a risky journey for diaspores. Endozoochory is achieved when diaspores are consumed and may germinate after the mastication, the gut and fecal matrix passage, all representing filters for diaspores. Nevertheless, endozoochory is a highly studied mechanism through numerous methods, notably based on the observation of frugivorous behavior, diaspores retrieved in feces or germination experiments. However, most of those methods consider partially the endozoochorous filters (ingestion, mastication, gut, feces). Hence, the combined effect of the methods and filters consideration may lead to biased inference of endozoochory. In this study, we used a collection of 52 brown bear ( Ursus arctos ) feces to highlight five methods inferring endozoochory. Two methods consider the ingestion filter and used metabarcoding of fecal eDNA to identify fleshy fruits (i) or plants during fruiting periods (ii). The third method (iii) was based on the intact propagules retrieved in feces, considering ingestion and mastication filters. Another method (iv) was based on the germination from disaggregated feces, considering up to the gut passage filter. The last method (v) was based on the germination from aggregated feces, considering the four filters. We compared the number of taxa, the community and the plant life forms inferred among methods. We inferred the largest number of taxa in method (iii), but the germination‐based methods inferred the most diverse plant life forms. We identify few shared taxa among methods. The metabarcoding‐based methods might be an interesting tool as a first approximation of endozoochory while detailing the diet. The method (v) appeared as the most reliable. Overall, we invite future studies to mitigate their interpretations according to the filters of endozoochory considered and plant detectability related to the method used
Loi agricole : un pesticide bientôt de retour sur le territoire français ? Interview par Nicolas Carvalho, France Info - Vrai ou Faux, l’émission, 31 mai 2025
No full textTélévisio
A simple pedotransfer function to estimate fine fraction organic carbon contents of surface horizons in French soils
No full textInternational audienceIt has been proposed to separate soil organic carbon (SOC) into two physical fractions, i.e., fine fraction organic carbon (OCfine) and coarse fraction organic carbon, to improve our ability to understand controlling factors and predict SOC contents and SOC stability. In this study, we aimed at building a simple pedotransfer function to estimate OCfine content measured using a size fractionation protocol in French soils. We define OCfine as SOCcontent measured in the < 50 μm fraction. We used information from the French Soil Quality Monitoring Network (RMQS, 706 observations) and from a literature search (245 observations) to build and validate the pedotransfer function. We used the Random Forest algorithm and partial dependence plots in an exploratory data analysis, to analyze the variables influencing OCfine contents and to study the shape of their relationship withOCfine. Using the knowledge gained from the exploratory analysis, we constructed a simple pedotransfer function.A slight inflection in the OCfine content was detected with increasing SOC content and a good approximation of OCfine content was reached using a second-degree polynomial relationship, with distinct coefficients depending on the land cover (i.e., croplands and permanent crops, grasslands, natural grasslands, and forests and shrubs). A cross-validation of the pedotransfer function led to an RMSE of 2.2 g kg−1 and an independentvalidation led to an RMSE of 2.0 g kg−1. The domain of applicability of the pedotransfer function was defined as being restricted to topsoil horizons and a SOC content ≤ 90 g kg−1. The estimated OCfine is deemed equivalent to a measure after a complete soil dispersion and a size fractionation protocol. The proposed pedotransfer function could be easily used in future soil carbon modeling frameworks. From a land management perspective, the shape of the relationship found between SOC and OCfine encourages increasing SOC levels to store more carbon in soil, including in the OCfine fraction
30 ans de suivi sanitaire du bouquetin des Alpes (Capra ibex) dans l'arc alpin : quelles leçons en tirer et quelles perspectives pour l'avenir ?
No full textMapping sex-and age-structure reveals lonely males at the front in an expanding brown bear population
No full textInternational audienceRange expansion is a common feature of invasive, reintroduced, and recovering populations. This process is driven by population growth and dispersal, and intrinsic species characteristics and dispersal mechanisms yield contrasting population structures in space. The spatial distribution of sex and age classes is key to understanding and forecasting range expansions, but mapping age and sex categories is methodologically challenging. Here, we develop an age-structured open population spatial capture recapture (OPSCR) model to understand how spatial sex and age structures can shape population dynamics, as well as recovery processes. We use the endangered Pyrenean brown bear population as a case study, analysing non-invasive monitoring data from 2017 to 2021. Results revealed an expansion front dominated by adult (>4 years) and subadult males (2-4 years), while females and juveniles (<2 years) prevailed at the core. This, together with an overall decrease in density towards the expansion front in spite of available habitat, suggest an expansion process constrained by female philopatry. Future projections suggest continued population growth even under demographic stochasticity, and potential for population spread with increased reproduction events at the periphery. Our novel OPSCR model allows for statistically rigorous mapping of the sex and age structure of a population from non-invasive monitoring data. This is an important step towards better understanding and predicting the dynamics of recovering populations worldwide. In the case of large carnivores, it could inform conservation action such as anticipating the adoption of damage prevention measures and raising awareness campaigns to improve co-existence in future expansion areas
New species and new records of families, genera and species of land snails (Mollusca, Gastropoda) from French Guiana
No full textInternational audienceThis paper presents an investigation of material collected during four intensive collecting trips of land snails in French Guiana from 1995 to 2020 and deposited in the French National Museum of Natural History collections. This material forms the basis of the following novelties: four families are reported for the first time from French Guiana: Diplommatinidae, Cystopeltidae, Thysanophoridae and Strobilopsidae; three native species: Lyroconus plagioptycha (Helicoidea, Thysanophoridae), Pupisoma macneilli (Pupilloidea, Valloniidae) and Strobilops morsei (Pupilloidea, Strobilopsidae) and one introduced species Diplosolenodes occidentalis (Veronicelloidea, Veronicellidae) are reported for the first time from French Guiana; five new species are described: Adelopoma quasimodo Gargominy, sp. nov. (Cyclophoroidea, Diplommatinidae), Lilloiconcha galbao Gargominy, sp. nov. (Punctoidea, Cystopeltidae), Protoglyptus bernicolae Gargominy, sp. nov. (Orthalicoidea, Bulimulidae), Pseudosubulina santi Gargominy, sp. nov. (Testacelloidea, Spiraxidae), and Happia decaensi Gargominy, sp. nov. (Scolodontoidea, Scolodontidae). Finally, Drymaeus surinamensis Vernhout, 1914, syn. nov. is considered as a new synonym of Mesembrinus lusorius (L. Pfeiffer, 1855), and Drymaeus arcuatostriatus (L. Pfeiffer, 1855) is proposed as the new identification of Drymaeus meesi sensu Tillier, 1980 non Breure, 1976.This paper presents an investigation of material collected during four intensive collecting trips of land snails in French Guiana from 1995 to 2020 and deposited in the French National Museum of Natural History collections. This material forms the basis of the following novelties: four families are reported for the first time from French Guiana: Diplommatinidae, Cystopeltidae, Thysanophoridae and Strobilopsidae; three native species: Lyroconus plagioptycha (Helicoidea, Thysanophoridae), Pupisoma macneilli (Pupilloidea, Valloniidae) and Strobilops morsei (Pupilloidea, Strobilopsidae) and one introduced species Diplosolenodes occidentalis (Veronicelloidea, Veronicellidae) are reported for the first time from French Guiana; five new species are described: Adelopoma quasimodo Gargominy, sp. nov. (Cyclophoroidea, Diplommatinidae), Lilloiconcha galbao Gargominy, sp. nov. (Punctoidea, Cystopeltidae), Protoglyptus bernicolae Gargominy, sp. nov. (Orthalicoidea, Bulimulidae), Pseudosubulina santi Gargominy, sp. nov. (Testacelloidea, Spiraxidae), and Happia decaensi Gargominy, sp. nov. (Scolodontoidea, Scolodontidae). Finally, Drymaeus surinamensis Vernhout, 1914, syn. nov. is considered as a new synonym of Mesembrinus lusorius (L. Pfeiffer, 1855), and Drymaeus arcuatostriatus (L. Pfeiffer, 1855) is proposed as the new identification of Drymaeus meesi sensu Tillier, 1980 non Breure, 1976. RésuméCet article présente une étude du matériel collecté lors de quatre missions de collecte intensive d'escargots terrestres en Guyane française de 1995 à 2020, dont le matériel est déposé dans les collections du Muséum national d'Histoire naturelle. Ce matériel a permis de révéler les nouveautés suivantes: quatre familles sont signalées pour la première fois de Guyane française: Diplommatinidae, Cystopeltidae, Thysanophoridae et Strobilopsidae ; trois espèces indigènes: Lyroconus plagioptycha (Helicoidea, Thysanophoridae), Pupisoma macneilli (Pupilloidea, Valloniidae) et Strobilops morsei (Pupilloidea, Strobilopsidae) et une espèce introduite Diplosolenodes occidentalis (Veronicelloidea, Veronicellidae) sont signalées pour la première fois de Guyane française ; cinq nouvelles espèces sont décrites:</div
Comparison of Metabarcoding and Shotgun Sequencing Confirms the Relevance of Chloroplastic rRNA Genes to Assess Community Structure of Lake Phytoplankton
No full textInternational audienceStudying the taxonomic composition of phytoplankton has been revolutionised by the emergence of metabarcoding approaches which theoretically provides access to all phytoplankton diversity. However, metabarcoding has its limitations, including biases related to primers efficiency in covering all phytoplanktonic taxonomic groups, biases introduced during amplification and due to databases completion. To assess the importance of these biases, we compared the compositions of phytoplankton in two large peri‐alpine lakes, using metabarcoding with primers targeting hypervariable regions of chloroplastic 16S and 23S rRNA, designed to cover the full taxonomic diversity of phytoplankton, and shotgun sequencing. To be able to directly compare the two methods, we extracted reads coming from the full sequences of these rRNA genes in shotgun sequencing data and used the same reference database for taxonomic assignation. The results show that the relative abundances of dominant groups of phytoplankton, including Cyanobacteria , Cryptophyta , Haptophyta , and Bacillariophyta , are consistent between the two approaches, validating the primers used for metabarcoding analysis. However, two phyla, Chlorophyta and non‐diatom Ochrophyta showed greater divergence in their relative abundance, due to under‐amplification or lack of amplification of certain taxonomic groups in metabarcoding. This is likely due to the high diversity of these groups, not covered yet by the reference databases, as well as a possible presence of introns in their choloroplastic ribosomal genes. These limitations are expected to be overcome with increasing reference database completion and the use of long‐read metabarcoding. Overall, our study confirms the relevance of using chloroplastic primers for assessing the phytoplankton composition of lakes
Born in heterogenous landscapes: birth timing, body mass and early development of roe deer fawns in contrasting habitats
No full textInternational audienceAlthough the widespread effects of climate change impact almost all ecosystems, we lack a detailed understanding of how wildlife that thrive in human‐dominated environments are able to adjust their life history to modifications in land use of their natural habitat. In particular, spatial variation in environmental conditions is predicted to influence body development during the crucial early life phase, with marked impacts on individual performance and population dynamics for long‐lived species. Large herbivores have increased substantially in number and distribution over the last half century across Europe. The synanthropic roe deer ( Capreolus capreolus ) has been particularly successful, gradually colonizing agricultural landscapes. However, little is known about how habitat heterogeneity in this heavily human‐impacted environment impacts demographic performance. Specifically, we predicted that fawns born in predominantly cultivated local habitats would achieve faster early development due to the food subsidies obtained from agricultural crops by their mothers. Contrary to our expectations, fawns in semi‐natural forest were around 10% heavier at birth than those born in more mixed (by 0.163 ± 0.058 kg) and open (by 0.169 ± 0.006 kg) agricultural habitats. However, the body mass of all fawns subsequently increased at a similar average rate (0.148 ± 0.058 kg/day) over the first 20 days of life, irrespective of their habitat. This habitat‐dependent variation in early life mass appeared to be driven by reproductive phenology, as (1) early‐born fawns were heavier than late‐born fawns, and (2) mothers living in forest gave birth around 10 days earlier than those living in the mixed and open sectors. Semi‐natural habitats might thus be the more suitable for fawn early development, despite the availability and abundance of energetically rich food resources for lactating mothers in open and mixed habitats
Évolutions du guide méthodologique pour l'inventaire en continu des ZNIEFF - NOTE 5 : Amélioration de la définition des Znieff abritant des chiroptères
No full textLe guide méthodologique national pour l’inventaire des Znieff en continu a été finalisé en 2014. Depuis cette étape et suite au recueil des besoins des acteurs régionaux, des évolutions de la méthode de 2014 sont apparues nécessaires.Cette note 5 apporte des précisions sur les caractéristiques écologiques et spatiales des Znieff de type I et de type II abritant des chiroptères