Le présent article se propose de faire le point sur les connaissances actuelles quant au rôle de la végétation dans la protection contre l'érosion hydrique de surface. Il expose, dans un premier temps, les mécanismes d'action de la végétation vis-à-vis des processus d'érosion et de sédimentation. Dans un deuxième temps, il présente des résultats de recherches sur l'efficacité des différentes formations végétales et l'importance du taux de couverture végétale pour la lutte contre l'érosion de ravines. Pour citer cet article : F.
International audienceThe ecological environment of three aquatic rodents was studied in the French Ardennes region. Two species, the coypu () and the common muskrat (), are invasive. By contrast the native European beaver () was extirpated from the region, subsequently reintroduced, and currently is protected. The aim of this study was to compare the ecological requirements of these three species and predict their future range distributions. We studied the relationship between the species and describe the characteristics of waterways and riparian vegetation in 29 sampling sites. Coypus and muskrats were observed in a variety of riparian habitats and their probability of detection appeared to be independent of waterway width, bank height or bank slope. The availability of numerous herbaceous plants, known to be consumed by these species, may facilitate their settlement. Muskrats are widespread on the French Ardennes waterways, but coypus have not yet colonised the northern part of the region. On the other hand, the beaver was observed primarily in the widest waterways with high banks, where woody plant species, such as , and , are found in abundance. Potentially favourable sites for beaver and coypu settlement were analysed to suggest appropriate management according to each species' status. However, the number of sample sites is weak, especially for sites with beaver, limiting our conclusion
A landslide was set off at Rilly-la-Montagne, on the 23 August 1986. The text analyses the conditions of the setting off and the evolution of this phenomenon until february 1988. Thus, it appears that, in the present times, particulars climatics conditions can be the origin of such risk on a slope of a sedimentary basin of the temperate zone.
U/Th ages of speleothems from the stepped-karst systems of Poissons, Cousances, and Rupt du Puits, are decreasing to the north Such a dia- chronous karstification is linked to the erosional retreat of the Infra-Cretaceous cover of clay and sand, and to the incision of the rivers in Tithonian limestones
Fluvial paleoforms and alluvial formations record 7, 10 and 1 1 incision stages, respectively in the valleys of the Marne, Saulx and Ornain rivers These stages are grouped into 4 major incision episodes, which occurred either before (very old episode D and old episode C), or after (intermediate episode B and recent episode A) the capture of the Ornain-Saulx paleonver towards the Marne
The karstic system of Poissons, older than 400 000 years, was reactivated during the D-incision episode, when wide but shallow valleys were encased into the Infra-Cretaceous exhumed surface of the Barrois Plateau The oldest karstic features of Cousances ("viailles") occurred during incision- episode C, when narrow Pleistocene valleys were deeply entrenched into the previous valley system Later shafts of the karst system of Cousances were shaped before circa 100 000 years, the approximate age of the first alluvial sediment of the Marne River deposited after the piracy of the Ornain-Saulx (B episode) U/Th and 14C ages of the active karst system of a tributary of the Saulx nver, the Rupt du Puits, range within the Ocean Oxygen Isotope stages 2 and 1 (A-episode)
From these data, the capture of the Ornain-Saulx paleonver occurred probably during Ocean Oxygen Isotope stage 6 Incision rates after this capture reach about 20-25 cm/ka in the clay of the Gault Formation near the elbow of the captured nver (Perthois), and only 7,5 cm/ka in the Tithonian limestones of the Barrois region
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