Search results for "POPULATIONS"
showing 10 items of 493 documents
DIVERSITE GENETIQUE ET PHENOLOGIE DE CYPERUS ESCULENTUS L. (CYPERACEAE) POUR UNE GESTION INTEGREE DE L'ESPECE DANS LES CULTURES DE HAUTE LANDE
2006
We studied the development, phenology, demography and genetic diversity of Cyperus esculentus (Cyperaceae), an invasive clonal perennial weed in the small-statured crops of Haute Lande, southwestern France. The goal was to understand its colonizing capacity and then make propositions for an integrated management of the species.The colonizing capacity of C. esculentus is linked to the huge subterranean vegetative development, with both foraging thanks to rhizomes and multiplication thanks to tubers. On the other hand, the local crop systems provide all the needs of the species: water, light and nutriments without competition by other weeds. Genetic analyses showed a low genetic diversity and…
Consequences of sown grass margin strip on weed flora
2010
The intensification of the management of weed populations, led by a potential decrease in the yield and quality of crop harvest, has largely induced their decline in arable zones across the last decades. This floristic decline in arable landscape, has induced a loss of a larger biodiversity because the presence of others organisms (birds, insects, mammals) are strongly linked with the abundance of trophic resources as weed are. To counter with this loss of biodiversity and to limit the negative impacts of farming practices on environment, numerous agri environmental schemes were launched through Europe. In France, sown grass strips were established by farmers along streams and rivers to lim…
Dynamique et assemblage des communautés adventices : Approche par modélisation statistique
2011
To develop solutions for a productive and sustainable agriculture, principles, theories, andmethods of ecology may contribute to understand the biological processes governing the agroecosystem.The present case study was based on data collected by a network of observatories of weeds covering the whole of France (‘Biovigilance Flore’) and aimed at establishing forrules governing the assemblage and dynamics of weed communities in fields grown with annual crops. We particularly studied the possible relationships between species within acommunity, as well as the relationships between communities and their environment. Analyses were based on species abundances to take account of their effect on c…
Changements à court terme de la composition des communautés de champignons mycorhiziens à arbuscules et des populations de Rhizophagus irregularis en…
2014
La mycorhize à arbuscule a un important potentiel d’amélioration de la nutrition minérale des plantes, fort utile dans le contexte agricole. Cependant, certaines pratiques culturales sont connues pour avoir un effet néfaste sur la diversité des champignons mycorhiziens à arbuscules (Glomeromycètes). Il est donc nécessaire de mieux comprendre les dynamiques de leurs communautés et populations pour pouvoir préserver et gérer le potentiel symbiotique. Dans cette étude, nous avons étudié les effets séparés et conjoints du retournement du sol et des fertilisations phosphatée et azotée du sol sur la structure des communautés des Glomeromycètes et sur les populations de l’espèce Rhizophagus irregu…
Microbial Community Structure and Density Under Different Tree Species in an Acid Forest Soil (Morvan, France)
2005
Overexploitation of forests to increase wood production has led to the replacement of native forest by large areas of monospecific tree plantations. In the present study, the effects of different monospecific tree cover plantations on density and composition of the indigenous soil microbial community are described. The experimental site of "Breuil-Chenue" in the Morvan (France) was the site of a comparison of a similar mineral soil under Norway spruce (Picea abies), Douglas fir (Pseudotuga menziesii), oak (Quercus sessiflora), and native forest [mixed stand dominated by oak and beech (Fagus sylvatica)]. Sampling was performed during winter (February) at three depths (0-5, 5-10, and 10-15 cm…
Evolution expérimentale
2010
National audience
Fonction et stabilité des réseaux de pollinisation et de la reproduction des plantes : impacts du paysage agricole
2021
National audience; Les interactions plantes-pollinisateurs, en conditionnant la reproduction sexuée de la majoritédes plantes à fleurs, sont essentielles tant au bien-être humain qu’au bon fonctionnement desécosystèmes. Pourtant, elles sont menacées par l’agriculture intensive et l’homogénéisation despaysages. La préservation en milieu agricole d’habitats favorables aux plantes sauvages et auxpollinisateurs, comme les bordures enherbées permanentes ou les bandes fleuries, pourraitpermettre de conserver les systèmes de pollinisation. Cette thèse associe l’écologie des réseauxet la génétique des populations pour évaluer l’influence de la composition du paysage agricole(habitats semi-naturels,…
Les contraintes.
2016
Les contraintes.
2010
Sex and Gender in the Scenarios of Human Evolution
2018
Contributors from a range of disciplines consider the disconnect between human evolutionary studies and the rest of evolutionary biology.The study of human evolution often seems to rely on scenarios and received wisdom rather than theory and methodology, with each new fossil or molecular analysis interpreted as supporting evidence for the presumed lineage of human ancestry. We might wonder why we should pursue new inquiries if we already know the story. Is paleoanthropology an evolutionary science? Are analyses of human evolution biological? In this volume, contributors from disciplines that range from paleoanthropology to philosophy of science consider the disconnect between human evolutio…