Résumé
Agricultural intensification reduces not only biodiversity in agroecosystems but also key ecosystem functions such as soil fertility. By reintroducing biological diversity in fields, weeds may enhance soil biological fertility through their influence on crop microbiota. However, letting weeds grow in crop fields will depend on weed competitiveness, farmers’ perception and acceptance, and on crop management, which influences the occurrence and the abundance of weeds in the field. This study assessed the use of eight weed species to modify wheat plant root endospheric mycobiota, and the applicability of using these plants for mycobiota enrichment in the field. By combining controlled lab experiments and field studies, we demonstrated that weeds act either as a refuge for a high diversity of fungi or as a vector for transferring fungi to the crop, particularly symbionts. Weeds differed in their competitive effect on wheat growth and only three species significantly reduced wheat growth. Interviews with farmers’ revealed that weed species were better known and more appreciated in crop fields by organic farmers than by conventional farmers. Floristic surveys confirmed that both weed occurrence and cover were higher in organic fields than in conventional fields. A multicriteria analysis showed that Trifolium repens and V. persica had the highest potential for promoting wheat plant mycobiota. Among the weed species tested, these two are worth considering as auxiliaries to improve soil biological fertility in crop fields. Their use with the goal of selecting appropriate crop mycobiota should be relatively easier in organic farms where weeds are better accepted, whereas their use in conventional farms would require raising farmers’ awareness of the benefits of weeds for soil fertility.
Auteurs, date et publication :
Auteurs Claire Ricono , Jie Hu , Philippe Vandenkoornhuyse , Audrey Alignier , Cendrine Mony
Publication : Agriculture, Ecosystems & Environment
Date : 2025
Volume : 379
Pages : 109357
Catégorie(s)
#CNRS #EcoGenO #Université de RennesAuteurs, date et publication :
Auteurs D Ho Tong Minh , Thuy Le Toan , Fabio Rocca , Stefano Tebaldini , Ludovic Villard , Maxime Réjou-Méchain , Jérôme Chave , Klaus Scipal
Date : 2025
Pages : 1321-1324
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Ciaran Laverty , Kyle D. Green , Jaimie T. A. Dick , Daniel Barrios-O’Neill , Paul J. Mensink , Vincent Médoc , Thierry Spataro , Joe M. Caffrey , Frances E. Lucy , Pieter Boets , J. Robert Britton , Josephine Pegg , Cathal Gallagher
Publication : Biological Invasions
Date : 2025
Volume : 19
Issue : 5
Pages : 1653-1665
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Insights into past marine carbon cycling and water mass properties can be obtained by means of geochemical proxies calibrated through controlled laboratory experiments with accurate seawater carbonate system (C-system) manipulations. Here, we explored the use of strontium/calcium ratio (Sr/Ca) of the calcite shells of benthic foraminifera as a potential seawater C-system proxy through a controlled growth experiment with two deep-sea species (Bulimina marginata and Cassidulina laevigata) and one intertidal species (Ammonia T6). To this aim, we used two experimental set-ups to decouple as much as possible the individual components of the carbonate system, i.e., changing pH at constant dissolved inorganic carbon (DIC) and changing DIC at constant pH. Four climatic chambers were used with different controlled concentrations of atmospheric pCO2 (180 ppm, 410 ppm, 1000 ppm, 1500 ppm). Our results demonstrated that pH did not influence the survival and growth of the three species. However, low DIC conditions (879 μmol kg−1) negatively affected B. marginata and C. laevigata through reduced growth, whereas no effect was observed for Ammonia T6. Our results also showed that Sr/Ca was positively correlated with total Alkalinity (TA), DIC and bicarbonate ion concentration ([HCO3−]) for Ammonia T6 and B. marginata; i.e., DIC and/or [HCO3−] were the main controlling factors. For these two species, the regression models were coherent with published data (existing so far only for Ammonia T6) and showed overall similar slopes but different intercepts, implying species-specific effects. Furthermore, the Sr/Ca - C-system relationship was not impacted by ontogenetic trends between chamber stages, which is a considerable advantage for paleo-applications. This applied particularly to Ammonia T6 that calcified many chambers compared to the two other species. However, no correlation with any of the C-system parameters was observed for Sr/Ca in C. laevigata. This might imply either a strong species-specific effect and/or a low tolerance to laboratory conditions leading to a physiological stress, thereby impacting the Sr incorporation into the calcite lattice of C. laevigata.
Auteurs, date et publication :
Auteurs M. Mojtahid , P. Depuydt , A. Mouret , S. Le Houedec , S. Fiorini , S. Chollet , F. Massol , F. Dohou , H. L. Filipsson , W. Boer , G. -J. Reichart , C. Barras
Publication : Chemical Geology
Date : 2023
Pages : 121396
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Geometric morphometry has evolved as a powerful tool to unravel species delimitations within the genus Aristolochia. A survey conducted on the variation of Aristolochia trilabiata flowers and leaves revealed an overlooked entity in its affinity, which is newly described herein as Aristolochia franzii. The new species differs from its relative A. trilabiata by various floral characters, notably the presence of papillae on both the upper and lower limb zones, the presence of a well defined medial upper limb zone, the number of veins on the lateral upper limb zone, a considerably shorter tube, and the relative position of upper and lower limb zones. Furthermore, the leaf shape of A. franzii is cordiform-elongate to hastate, compared to the consistently more compact and shorter cordiform leaves of A. trilabiata. So far, A. franzii has been recorded from Northern Brazil (Amazonas) and French Guiana. An illustration of the diagnostic characters and comparison with A. trilabiata is provided, as well as the geographic distribution and a preliminary assessment of the conservation status.
Auteurs, date et publication :
Auteurs Dominik Frank
Publication : Brittonia
Date : 2025
Volume : 75
Issue : 4
Pages : 358-368
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Territoriality has been widely described across many animal taxa, where the acquisition and defence of a territory are critical for the fitness of an individual. Extensive evidence suggests that androgens are involved in the modulation of territorial behaviours in male vertebrates. Short-term increase of androgen following a territorial encounter appears to favour the outcome of a challenge. The “Challenge Hypothesis” proposed by Wingfield and colleagues outlines the existence of a positive feedback relationship between androgen and social challenges (e.g., territorial intrusions) in male vertebrates. Here we tested the challenge hypothesis in the highly territorial poison frog, Allobates femoralis, in its natural habitat by exposing males to simulated territorial intrusions in the form of acoustic playbacks. We quantified repeatedly androgen concentrations of individual males via a non-invasive water-borne sampling approach. Our results show that A. femoralis males exhibited a positive behavioural and androgenic response after being confronted to simulated territorial intrusions, providing support for the Challenge Hypothesis in a territorial frog.
Auteurs, date et publication :
Auteurs Camilo Rodríguez , Leonida Fusani , Gaëlle Raboisson , Walter Hödl , Eva Ringler , Virginie Canoine
Publication : General and Comparative Endocrinology
Date : 2022
Volume : 326
Pages : 114046
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Contribution of the collections of the Muséum national d’Histoire naturelle and Didier Morin to the knowledge of the Batrachideinae and Lophotettiginae (Orthoptera, Tetrigidae) of French Guiana. Two important collections of Tetrigidae Rambur, 1838 containing more than 1000 individuals from French Guiana were consulted and revised in order to complete the knowledge of this group in this area. Given the large number of specimens to be treated, the analyses focussed in a first time on two subfamilies, Batrachideinae Bolívar, 1887 and Lophotettiginae Hancock, 1909, representing 489 individuals of which 456 were identified to species level. The results show the presence of 14 taxa, of which 11 are new to the department and four are new to science and described in this article: Paurotarsus pennatulus n. sp., Scaria guyanensis Doucet & Itrac-Bruneau, n. sp., Scaria macromaculata Doucet & Itrac-Bruneau, n. sp. and Scaria madeleinae n. sp. In addition, the female of Phelene maroon Cadena-Castañeda & Tumbrinck, 2021 and the male of Tettigidea pulchella Rehn, 1904, unknown until now, are described thanks to this material. As a result of these numerous contributions, a new identification key for the two studied subfamilies is proposed.
Auteurs, date et publication :
Auteurs Raphaëlle Itrac-Bruneau , Guillaume Doucet
Publication : Zoosystema
Date : 2023
Volume : 45
Issue : 20
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Forest dynamic models predict the current and future states of ecosystems and are a nexus between physiological processes and empirical data, forest plot inventories and remote-sensing information. The problem of biodiversity representation in these models has long been an impediment to a detailed understanding of ecosystem processes. This challenge is amplified in species-rich and high-carbon tropical forests. Here we describe an individual-based and spatially explicit forest growth simulator, TROLL, that integrates recent advances in plant physiology. Processes (carbon assimilation, allocation, reproduction, and mortality) are linked to species-specific functional traits, and the model was parameterized for an Amazonian tropical rainforest. We simulated a forest regeneration experiment from bare soil, and we validated it against observations at our sites. Simulated forest regeneration compared well with observations for stem densities, gross primary productivity, aboveground biomass, and floristic composition. After 500years of regrowth, the simulated forest displayed structural characteristics similar to observations (e.g., leaf area index and trunk diameter distribution). We then assessed the model's sensitivity to a number of key model parameters: light extinction coefficient and carbon quantum yield, and to a lesser extent mortality rate, and carbon allocation, all influenced ecosystem features. To illustrate the potential of the approach, we tested whether variation in species richness and composition influenced ecosystem properties. Overall, species richness had a positive effect on ecosystem processes, but this effect was controlled by the identity of species rather by richness per se. Also, functional trait community means had a stronger effect than functional diversity on ecosystem processes. TROLL should be applicable to many tropical forests sites, and data requirement is tailored to ongoing trait collection efforts. Such a model should foster the dialogue between ecology and the vegetation modeling community, help improve the predictive power of models, and eventually better inform policy choices.
Auteurs, date et publication :
Auteurs Isabelle Marechaux , Jerome Chave
Publication : ECOLOGICAL MONOGRAPHS
Date : 2017
Volume : 87
Issue : 4
Pages : 632-664
Catégorie(s)
#ANR-Citation #CIRAD #CNRS #FORET NouraguesRésumé
Baseline error correction is critical for airborne SAR tomography as the actual flight trajectory often deviates from the designed one due to turbulence, which may lead to large sidelobes or even complete defocusing in the tomograms. Current baseline error correction methods, however, are susceptible to heavy decorrelation noise. To mitigate the adverse effect of decorrelation noise, in this paper, a novel method for airborne SAR tomography baseline errors correction driven by small baseline interferometric phase is proposed. In this method, a novel mathematical model that relates interferometric phase to the baseline error differences is first derived, then a small baseline interferometric pairs selection strategy is employed to estimate the baseline error differences through an alternate iterative algorithm, and finally the baseline errors are obtained through accumulating summation of the baseline error differences. The use of small baseline interferograms can avoid the phase linking processing and thereby greatly alleviate the heavy decorrelation effect. Both simulated and real airborne P-band SAR tomography experiments have demonstrated that the proposed method can achieve more accurate and robust estimation of baseline errors and is more tolerant to decorrelation noise than the well-known phase center double localization (PCDL) method.
Auteurs, date et publication :
Auteurs Guobing Zeng , Huaping Xu , Wei Liu , Aifang Liu , Yuan Wang
Publication : IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date : 2025
Volume : 16
Pages : 10007-10021
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Threadsnakes are known for their conserved external morphology and historically controversial systematics, challenging taxonomic, biogeographic and evolutionary researches in these fields. Recent morphological studies—mostly based on µCT data of the skull and lower jaw—have resolved systematic issues within the group, for instance leading to the description of new taxa or re-positioning little-known scolecophidian taxa in the tree of life. Herein we describe a new polymorphic species of the genus Siagonodon from Amazonia based on morphological (external, osteology and hemipenis) and molecular data, and provide the first hemipenial description for the genus. We also reassign Siagonodon acutirostris to the genus Trilepida based on osteological data in combination with molecular evidence. The new species described represents an evolutionary paradox for scolecophidians because the species displays a remarkable variation in the shape of the snout region that is otherwise always highly conserved in this clade. Finally, this study reinforces the importance of protected areas as essential in maintaining vertebrate populations, including those that are not yet formally described.
Auteurs, date et publication :
Auteurs Angele Martins , Manuella Folly , Guilherme Nunes Ferreira , Antônio Samuel Garcia Da Silva , Claudia Koch , Antoine Fouquet , Alessandra Machado , Ricardo Tadeu Lopes , Roberta Pinto , Miguel Trefaut Rodrigues , Paulo Passos
Publication : Vertebrate Zoology
Date : 2023
Volume : 73
Pages : 345-366