The development of arable cultivation in the south-east of England and its relationship with vegetation cover: A honeymoon period for biodiversity?

The onset of prehistoric farming brought unprecedented changes to landscapes and their biodiversity. Past biodiversity patterns are broadly understood for different parts of Europe, and demonstrate trajectories that have been linked to prehistoric and historic demographic transitions, and associated land-use practices. To our knowledge, this paper is the first attempt to directly link evidence of agricultural practice from the archaeological record to biodiversity patterns. Records of fossil pollen are used to estimate plant and landscape diversity patterns, and novel approaches are employed to analyse 1194 harmonised archaeobotanical samples (plant macrofossil remains) spanning the prehistoric and Roman periods, from southern England. We demonstrate changes in the use of crops and gathered edible plants and non-linear trends in cultivation practices. Whilst, overall, cereal production is characterised by ever larger and extensive regimes, different trajectories are evident for most of early prehistory, the Middle Iron Age and the Late Roman period. Comparisons with the Shannon diversity of fossil pollen records from the same region suggest a positive relationship between developing agricultural regimes and landscape scale biodiversity during the prehistoric period. The Roman period represents a tipping point in the relationship between expanding agriculture and pollen diversity, with declining pollen diversity evident in the records from the region

Suppression of the Bgl+ phenotype of a delta hns strain of Escherichia coli by a Bacillus subtilis antiterminator binding site.

International audienceBacillus subtilis, like Escherichia coli, possesses several sets of genes involved in the utilization of beta-glucosides. In E. coli, all these genes are cryptic, including the genes forming the bgl operon, thus leading to a Bgl- phenotype. We screened for B. subtilis chromosomal DNA fragments capable of reverting the Bgl+ phenotype associated with an E. coli hns mutant to the Bgl- wild-type phenotype. One B. subtilis chromosomal fragment having this property was selected. It contained a putative Ribonucleic AntiTerminator binding site (RAT sequence) upstream from the bgl gene. Deletion studies as well as subcloning experiments allowed us to prove that the putative B. subtilis of the E. coli bgl operon. We propose that this repression results from the titration of the BglG antiterminator protein of E. coli bgl operon by our putative B. subtilis bglP RAT sequence. Thus, we report evidence for a new cross interaction between heterologous RAT-antiterminator protein pairs

Gérer l’ambroisie à feuilles d’armoise en agriculture biologique

National audienceManaging common ragweed in organic agriculture Common ragweed (Ambrosia artemisiifolia L.) is an invasive plant native to North America, capable of developing rapidly in many environments: agricultural fields, roadsides, construction sites, wastelands, riverbanks. Pollen, emitted at the end of summer, causes strong allergic reactions in sensitive people (rhinitis, asthma, etc.). It is also a threat to agriculture, as this annual plant can cause significant yield losses if it is not controlled. A study was conducted to analyze the practices of organic farmers in arable crop systems to control ragweed, as well as their level of knowledge of this plant according to their location. The results of this work show that ragweed is managed in organic farming by combining preventive and curative practices commonly used in this production method to control summer weed flora: diversified rotation, insertion of alfalfa, observation of plots, cleaning of the surroundings and seeds, stubble cultivation, false seeding, mechanical weeding in cultivation. The specificity of ambrosia management, given its high capacity for expansion, lies in increased surveillance and necessarily enhanced prevention. The solutions to control it can thus go as far as drastically reducing the return of favourable crops - sunflower, maize, soybean - in the rotation, or even manual weeding. Analysing the alternative management methods used in organic farming is interesting, to see how to optimise their mobilisation by organic farmers in regions differently affected by ragweed, in particular newly affected regions, but also to transpose them into a conventional system in a context of reduced use of plant protection products.L’ambroisie à feuilles d’armoise (Ambrosia artemisiifolia L.) est une plante envahissante originaire d’Amérique du Nord, capable de se développer rapidement dans de nombreux milieux : parcelles agricoles, bords de route, chantiers, friches, bords de rivière. Le pollen, émis en fin d’été, provoque de fortes réactions allergiques chez les personnes sensibles. C’est aussi une menace pour l’agriculture, car cette plante annuelle peut provoquer des pertes de rendement importantes si elle n’est pas contrôlée. Une étude a été menée pour analyser les pratiques d’agriculteurs bio, en systèmes céréaliers, pour contrôler l’ambroisie à feuilles d’armoise, ainsi que leur niveau de connaissance de cette plante selon leur région. Les résultats de ce travail montrent que l’ambroisie se gère en AB en combinant pratiques préventives et curatives couramment utilisées dans ce mode de production pour contrôler la flore adventice estivale : rotation diversifiée, insertion d’une luzerne de 2 ou 3 ans, observation des parcelles, nettoyage des abords et des semences, déchaumages, faux-semis, désherbage mécanique en culture. La spécificité de la gestion de l’ambroisie, face à sa forte capacité d’expansion, réside en une surveillance accrue et une prévention nécessairement renforcée. Les solutions pour la contrôler peuvent ainsi aller jusqu’à une diminution drastique du retour de cultures favorables –tournesol, maïs, soja- dans la rotation, voire au désherbage manuel. Analyser les méthodes de gestion alternatives utilisées en AB est intéressant, pour voir comment optimiser leur mobilisation par des agriculteurs bio dans des régions différemment concernées par l’ambroisie, notamment des régions nouvellement touchées, mais aussi pour les transposer en système conventionnel dans un contexte de réduction de l’utilisation de produits phytosanitaires

Canopy bidirectional reflectance calculation based on Adding method and SAIL formalism: AddingS / AddingSD

The SAIL model (proposed by Verhoef) is largely used in the remote sensing community to calculate the canopy Bidirectional Reflectance Distribution Function. The simulation results appear acceptable compared to observations especially for not very dense planophile vegetation. However, for erectophile dense crops (e.g. corn) the simulations appear less accurate. This inadequacy is due to the assumption that the multiple scattered fluxes are isotropically distributed. The SAIL parameters are interpretable at the level of elementary layer components. Now, the Adding method (initially proposed by Van de Hulst) provides a good framework to model the radiative transfer inside a vegetation layer, but its parameter estimation lies on very simple geometric modeling of the canopy. In this paper, we first propose an adaptation of the Adding method using the SAIL model canopy representation in the turbid case: it is called AddingS model. Such an approach allows to overcome the isotropy assumption. Second, AddingS is extended to the Discrete case: defining the AddingSDmodel. It allows to take into account the multi hot spot effect. Moreover, the AddingS and AddingSD models allow to check the energy conservation in respectively turbid and discrete cases. Finally, in order to keep reasonable time performance, a fast computation method was developed

Performance of change detection using remotely sensed data and evidential fusion: Comparison of three cases of application.

International audienc

Cytotoxic and genotoxic effects of cylindrospermopsin in mice treated by gavage or intraperitoneal injection

Article first published online: 19 AUG 2010Abstract not availableEmmanuelle Bazin, Sylvie Huet, Gérard Jarry, Ludovic Le Hégarat, John S. Munday, Andrew R. Humpage, andValérie Fessar

AIMWATER Analysis, investigation and monitoring of water resources for the management of multi-purpose reservoirs. Final report

AIMWATER : Contract n" ENV4-CT98-0740 (DG 12-ESCY)SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : GR 1996 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc