Postdispersal weed seed predation ranged between 19 to 84% per week following a species preference rank

Postdispersal weed seed predation ranged between 19 to 84% per week following a species preference ran

Prédire l’occurrence des espèces adventices : quelles échelles de temps et d’espace ?

Comprendre la distribution spatiale des communautés végétales et les processus écologiques sous-jacents constituent un enjeu majeur en particulier pour la gestion intégrée de la flore adventice. Le projet européen PURE ("Pesticide Use-and-risk Reduction in European farming systems with Integrated Pest Management") vise à concevoir, à partir d’études empiriques identifiant les déterminants locaux et régionaux de la distribution d’espèces nuisibles, des paysages qui leur soient défavorables. Les déterminants de la distribution des adventices sont généralement étudiés à l’échelle de la parcelle or, de récentes études suggèrent qu’il est également nécessaire de tenir compte du contexte paysager. Par ailleurs, les paysages agricoles constituent des systèmes dynamiques dans lesquels les cultures et les pratiques se succèdent. Nous faisons l’hypothèse que la flore adventice qui s’exprime dans une parcelle une année donnée dépend à la fois des pratiques appliquées l’année donnée mais également les années précédentes et des pratiques sur les parcelles voisines. Notre étude vise ainsi à identifier quelles échelles de temps et d’espace sont les plus pertinentes pour prédire l’occurrence des espèces adventices. La flore adventice a été échantillonnée dans 58 parcelles de la zone de Fénay pendant 4 années consécutives. Les pratiques de ces parcelles ont été recensées de 2004 à 2011 par enquêtes auprès des agriculteurs. Nous avons adopté une approche de sélection de modèles basée sur le critère d’AIC, complétée par une validation croisée pour quantifier les capacités prédictives du meilleur modèle. Les premiers résultats montrent que l’intégration d’échelles de temps et d’espace larges améliore la description de la distribution des adventices

Origine et intérêt écologique des sols limoneux des dépressions humides du massif dunaire d’Hatainville (Manche)

Sur les côtes européennes, les massifs dunaires sont caractérisés par de nombreux habitats à forte valeur écologique qu’explique la présence d’une nappe phréatique. Depuis une vingtaine d’années, les plantes pionnières et prairiales de ces habitats subissent une tendance très importante à la régression. Le massif dunaire d’Hatainville en est un parfait exemple. La protection des espèces herbacées rares passe par une meilleure connaissance des sols et de leur fonctionnement. Une étude pédologique a été menée sur les sols limoneux des dépressions humides du massif, sols dont la découverte fut inattendue. Ces sols présentent en effet la particularité de détenir les espèces pionnières et prairiales les plus riches. Les résultats analytiques ont permis de préciser l’origine et l’intérêt écologique des sols limoneux. Ils soulignent également la nécessité de préserver ce matériel édaphique dans le cadre d’une gestion conservatoire de la biodiversité du massif dunaire.Along the European coasts, dune massifs are characterized by numerous settlements with great ecological value in relation to phreatic water. Since about twenty years, pioneer and grassy species of those settlements are subjected to substantial decline. Dune massif of Hatainville is a perfect sample of this regressive trend. Protection of scarce grassy species requires a better knowledge of soils and their dynamics. Pedological investigation has been carried out concerning unexpected silty soils of massif dune slacks. These soils are original insofar as they own richest pioneer and grassy species. Origin and ecological value of the silty soils have been cleared by analytic data. These data also underline the need for preserving this edaphic material within the conservatory management of the biodiversity of dune massif

Prise en compte de la diversité végétale arborée chez les paysagistes

Cet article vise à interroger la relation entre la diversité arborée et la pratique du projet de paysage à travers la littérature existante d’histoire des jardins publiée au cours des trois derniers siècles. La lecture de ces documents a permis d’identifier quatre grandes « ères » qui ont non seulement fait évoluer des manières de penser et de dessiner les projets, mais aussi d’intégrer et de conduire l’arbre dans les aménagements de grands parcs et domaines privés du xviie siècle à ceux d’aujourd’hui, rendus publics et urbains. Ainsi, du xviie au xxe siècle, de l’art des jardins classique à l’urbanisme fonctionnaliste, nous verrons comment il est déjà possible de dégager des paramètres d’organisation, de structure et de fonctionnement qui témoignent avant l’heure d’une dimension de la diversité arborée. Cela a pour objectif de replacer dans l’histoire cet élément de nature présent dans les villes comme un vecteur et/ou un support de biodiversité.This article focuses on the relation between arborescent plant diversity and the landscape project in the literature of the history of gardens published during the last three centuries. The study if these documents has made it possible to identify four major “eras” which not only contributed to changing the way of thinking about and designing projects, but also integrated and used the arborescent plant as a defining component in the development of major parks and private domains from the 17th century up until today, and which have now become public and urban spaces. Thus, from the 17th to the 20th century, spanning from the art of classic gardens to the trend of functional urbanism, the article shows how it is possible to identify the parameters relating to forms of organisation, structure and practise which point to the early presence of tree diversity. The objective is to place within the historical framework this natural element present in cities as a vector of and/or a support for biodiversity

THE IMPACT OF STORAGE CONDITIONS ON THE FOREST BIOMASS QUALITY FOR BIOFUELS PRODUCTION

Biomass quality is an essential parameter for the production of biofuels both by thermal ways (gasification, pyrolysis, torrefaction, etc) or biochemical ways (enzymatic hydrolysis and yeast saccharification). Storage is one of the most important parameters to be taken in account in the logistics chains of biomass supply for biofuel conversion sites. Morever, some benefits in terms of biomass quality can be obtained by storing biomass prior transportation or usage. In this case, storage can be considered as a pre-treatment of biomass for biofuel production. In this project, we have studied the evolution of biomass quality of different wooden resources (softwoods and hardwoods; short/very-short rotation coppices and residues of forest exploitation) stored under different conditions : seasons (spring/summer or autumn/winter), sites (forest roadside and storage platforms; uncovered and covered; under water sprinkling). Two locations were also tested, one in Bordeaux area (southwest of France) and the second in Dijon area (northeast of France). Different piles of approximately 10 m3 (2.5 to 3.5 tons of wood chips) were constituted for each modality. Samples were taken from two different levels of the piles at different intervals of storage (0 to 6 months). The following biomass quality parameters were followed : moisture content, elemental (C, H, O, N, S, Cl) and chemical (extractives, lignin, polysaccharides – cellulose and hemicelluloses, C5 and C6 sugars contents) composition; heating value; ash content, fusibility behaviour and composition. The results obtained indicated that the conditions of storage strongly influence the biomass quality, especially for the thermal conversion. The type of initial raw material (softwoods or hardwoods / short/very-short rotation coppices and residues of forest exploitation) are also of major importance, especially if the biomass material is stored with or without leaves. In that way, the season aspect becomes very important. Water sprinkling is an interesting way to remove certain compounds, such ash constituents or extractives, partially responsible for tar formation. On the other way, in this case a compulsory drying step is needed and a careful energy balance is needed in order to evaluate the pertinence or not of this technology. Concerning the biochemical conversion, no major differences were observed for the mono/polysaccharides contents. However, the removal of certain elements/substances could impact the enzymatic hydrolysis and fermentation for bioethanol production

Col-OSSOS: The Colours of the Outer Solar System Origins Survey

The Colours of the Outer Solar System Origins Survey (Col-OSSOS) is acquiring near-simultaneous $g$, $r$, and $J$ photometry of unprecedented precision with the Gemini North Telescope, targeting nearly a hundred trans-Neptunian objects (TNOs) brighter than $m_r=23.6$ mag discovered in the Outer Solar System Origins Survey. Combining the optical and near-infrared photometry with the well-characterized detection efficiency of the Col-OSSOS target sample will provide the first flux-limited compositional dynamical map of the outer Solar System. In this paper, we describe our observing strategy and detail the data reduction processes we employ, including techniques to mitigate the impact of rotational variability. We present optical and near-infrared colors for 35 TNOs. We find two taxonomic groups for the dynamically excited TNOs, the neutral and red classes, which divide at $g-r \simeq 0.75$. Based on simple albedo and orbital distribution assumptions, we find that the neutral class outnumbers the red class, with a ratio of 4:1 and potentially as high as 11:1. Including in our analysis constraints from the cold classical objects, which are known to exhibit unique albedos and $r-z$ colors, we find that within our measurement uncertainty, our observations are consistent with the primordial Solar System protoplanetesimal disk being neutral-class-dominated, with two major compositional divisions in $grJ$ color space.Comment: Accepted to ApJS; on-line supplemental files will be available with the AJS published version of the pape

Influence du paysage et des pratiques agricoles sur le contrôle biologique des graines d'adventices par les carabiques

Farmland biodiversity and its associated ecosystem services are affected by agricultural activities at multiple spatial scales. Among these services, the regulation of weeds by invertebrate seed predators has received much attention recently but little is known about the relative effect of local management and landscape context of fields on this process. We monitored seed predation on four common weed species and carabid communities in 28 winter-cereals fields during five consecutive weeks in spring 2010. These fields were situated in contrasted landscape contexts and varied in terms of intensity of pesticide treatments and soil tillage regimes. Weed seed predation was strongly and positively related to the Shannon diversity of (strictly) granivorous carabids and to the activity–density of omnivorous carabids but negatively to the richness of omnivorous carabids. Weed seed predation and granivore diversity were positively related to landscape diversity and the proportion cover of temporary grassland within a 1000 m radius around focal fields and were negatively affected by the intensity of local pesticide treatments. No-till systems sheltered higher diversity of granivorous carabids but did not show higher seed predation rates. We showed that landscape composition factors had a higher relative influence than local practices factors on weed seed predation service. Consequently, weed management strategies should not only consider the management of single fields but also the surrounding landscape to preserve carabid biodiversity and enhance weed seed predation service

Humid Evolution of Haze in the Atmosphere of Super-Earths in the Habitable Zone

Photochemical hazes are expected to form and significantly contribute to the chemical and radiative balance of exoplanets with relatively moderate temperatures, possibly in the habitable zone of their host star. In the presence of humidity, haze particles might thus serve as cloud condensation nuclei and trigger the formation of water droplets. In the present work, we are interested in the chemical impact of such a close interaction between photochemical hazes and humidity on the organic content composing the hazes and on the capacity to generate organic molecules with high prebiotic potential. For this purpose, we explore experimentally the sweet spot by combining N-dominated super-Earth exoplanets in agreement with Titan's rich organic photochemistry and humid conditions expected for exoplanets in habitable zones. A logarithmic increase with time is observed for the relative abundance of oxygenated species, with O-containing molecules dominating after 1 month only. The rapidity of the process suggests that the humid evolution of N-rich organic haze provides an efficient source of molecules with high prebiotic potential

Evaluation of the sterilization effect on biphasic scaffold based on bioactive glass and polymer honeycomb membrane

The sterilization is a core preoccupation when it comes to implantable biomaterials. The most common in industry is the gamma sterilization; however, the radiation used in this method can induce modifications in the material properties. This study investigates the impact of such radiations on the physicochemical properties and biological toxicity of a new biomaterial based on a poly-l-co-d,l-lactide polymer honeycomb membrane and bioactive glass (BG), combined, to form an assembly (membrane/BG assembly). The investigated BGs are the S53P4, which is FDA approved and clinically used, and 13-93B20, a BG containing boron promising for bone regeneration. Infrared and photoluminescence measurements revealed that, upon irradiation, defects are created in the BGs molecular matrix. Defects were identified to be mainly non-bridging oxygen hole center and occur in higher proportion in the 13-93B20 making it more sensitive to irradiation compared to the S53P4. However, the irradiation does not significantly impact the structure of the BGs. On the membrane side, the molecular weight is divided by two resulting in a lower shear stress resistance. However, the membrane honeycomb topography does not seem to be impacted by the irradiation. In contact with cells, no toxicity effect was observed, and BGs keep their bioactive properties by releasing ions beneficial to the cell fate and with no influence on apatite precipitation speed. Overall, this study showed that, despite some impact on the physicochemical properties, the irradiation does not induce deleterious effect on the membrane/BG assemblies and is therefore a suitable method for the sterilization of this novel biomaterial.Peer reviewe

TWIST1 promotes invasion through mesenchymal change in human glioblastoma

Background: Tumor cell invasion into adjacent normal brain is a mesenchymal feature of GBM and a major factor contributing to their dismal outcomes. Therefore, better understandings of mechanisms that promote mesenchymal change in GBM are of great clinical importance to address invasion. We previously showed that the bHLH transcription factor TWIST1 which orchestrates carcinoma metastasis through an epithelial mesenchymal transition (EMT) is upregulated in GBM and promotes invasion of the SF767 GBM cell line in vitro. Results: To further define TWIST1 functions in GBM we tested the impact of TWIST1 over-expression on invasion in vivo and its impact on gene expression. We found that TWIST1 significantly increased SNB19 and T98G cell line invasion in orthotopic xenotransplants and increased expression of genes in functional categories associated with adhesion, extracellular matrix proteins, cell motility and locomotion, cell migration and actin cytoskeleton organization. Consistent with this TWIST1 reduced cell aggregation, promoted actin cytoskeletal re-organization and enhanced migration and adhesion to fibronectin substrates. Individual genes upregulated by TWIST1 known to promote EMT and/or GBM invasion included SNAI2, MMP2, HGF, FAP and FN1. Distinct from carcinoma EMT, TWIST1 did not generate an E- to N-cadherin "switch" in GBM cell lines. The clinical relevance of putative TWIST target genes SNAI2 and fibroblast activation protein alpha (FAP) identified in vitro was confirmed by their highly correlated expression with TWIST1 in 39 human tumors. The potential therapeutic importance of inhibiting TWIST1 was also shown through a decrease in cell invasion in vitro and growth of GBM stem cells. Conclusions: Together these studies demonstrated that TWIST1 enhances GBM invasion in concert with mesenchymal change not involving the canonical cadherin switch of carcinoma EMT. Given the recent recognition that mesenchymal change in GBMs is associated with increased malignancy, these findings support the potential therapeutic importance of strategies to subvert TWIST1-mediated mesenchymal change