Evaluer la diversité du paysage des pâturages africains

La diversité d'un paysage peut être mesurée par une application de la théorie de l'information à l'analyse d'un panorama découpé en plans selon les facettes géomorphologiques et les types de végétation. Des applications sont proposées sur des paysages d'Afrique tropicale septentrionale. (Résumé d'auteur

Sur les « niches écologiques » de quelques plantes du Languedoc

The distribution in space, and the propensity to be associated with other plant species, can well be considered as important dimensions of the ecological niche of a plant. This is demonstrated by the results obtained during a vegetation survey of the « garrigues » around Montpellie

Rapport technique de mission au CPATSA (Centro de Pesquisa Agropecuaria do Tropico Semi-Arido) ler - 15 août 1981.

L'objectif essentiel de Ia mission est d'aider les responsables et les chercheurs du CPATSA en ce qui concerne les projets du Programme natIonal de recherches sur les ressources naturelles et socio-économiques du Tropique semi-aride (PNP 027).bitstream/item/211263/1/flht-03692.pd

Calculs comparés de biodiversité dans quelques forêts de Provence

La biodiversité de la végétation peut être précisément calculée sous forme de quantités d’information selon la théorie éponyme. Diverses facettes de la richesse floristique, de la répartition des fréquences spécifiques, de la structuration spatiale, peuvent ainsi être définies et recevoir une valeur numérique caractérisant leur diversité. Une application est donnée pour un échantillon de placettes forestières installées en PACA (réseau Sylvipaca du CRPF). Il est ainsi démontré que des éclaircies intensives peuvent procurer une biodiversité aussi forte que celle des témoins laissés en vieillissement. Divers cas correspondant aux principaux peuplements de la région sont ainsi étudiés et commentés. Une synthèse régionale est aussi sommairement esquissée, montrant que la diversité entre peuplements différents est très supérieure à celle rencontrée au sein d’une communauté donnée. L’étude de la biodiversité floristique dite ordinaire montre bien que l’intervention des forestiers, telle qu’usuellement pratiquée dans la région, n’a généralement pas d’impact négatif. Bien au contraire dans les peuplements initialement fermés, la sylviculture provoque une mise en lumière favorisant la biodiversité

Rückenwind für Klimaneutralität

RÜCKENWIND FÜR KLIMANEUTRALITÄT Rückenwind für Klimaneutralität / Rosenkranz, Gerd (Rights reserved) ( -

The Impact of the Species–Area Relationship on Estimates of Paleodiversity

Estimates of paleodiversity patterns through time have relied on datasets that lump taxonomic occurrences from geographic areas of varying size per interval of time. In essence, such estimates assume that the species–area effect, whereby more species are recorded from larger geographic areas, is negligible for fossil data. We tested this assumption by using the newly developed Miocene Mammal Mapping Project database of western North American fossil mammals and its associated analysis tools to empirically determine the geographic area that contributed to species diversity counts in successive temporal bins. The results indicate that a species–area effect markedly influences counts of fossil species, just as variable spatial sampling influences diversity counts on the modern landscape. Removing this bias suggests some traditionally recognized peaks in paleodiversity are just artifacts of the species–area effect while others stand out as meriting further attention. This discovery means that there is great potential for refining existing time-series estimates of paleodiversity, and for using species–area relationships to more reliably understand the magnitude and timing of such biotically important events as extinction, lineage diversification, and long-term trends in ecological structure

Social Deprivation Is Associated With Lower Access to Pre-emptive Kidney Transplantation and More Urgent-Start Dialysis in the Pediatric Population

Introduction Socioeconomic status (SES) is recognized as an important determinant of kidney health. We aimed to evaluate the association of social deprivation with different indicators at kidney replacement therapy (KRT) initiation in the French pediatric metropolitan population. Methods All patients with end-stage kidney disease (ESKD) who started KRT before 20 years old in France between 2002 and 2015 were included. We investigated different indicators at KRT initiation, which are as follows: KRT modality (dialysis vs. pre-emptive transplantation), late referral to a nephrologist, and dialysis modality (hemodialysis [HD] vs. peritoneal dialysis [PD], urgent vs. planned start of dialysis, use of catheter vs. use of fistula for HD vascular access). An ecological index (European Deprivation Index [EDI]) was used as a proxy for social deprivation. Results A total of 1115 patients were included (males 59%, median age at dialysis 14.4 years, glomerular/vascular diseases 36.8%). The most deprived group represented 38.7% of the patients, suggesting pediatric patients with ESKD come from a more socially deprived background. The most deprived group was more likely to initiate KRT with dialysis versus kidney transplantation. Among patients on HD, the odds of starting treatment in emergency with a catheter was >2-fold higher for the most deprived compared with the least deprived children (adjusted odds ratio [aOR] 2.35, 95% CI 1.16–4.78). Conclusion Children from the most deprived area have lower access to pre-emptive transplantation, have lower access to PD, tend to be late referred to a nephrologist, and have more urgent initiation of HD with a catheter