No abstract

R������.Las riberas son uno de los aspectos más importantes a considerar para cuantificar y calificar el estado ecológico de los ecosistemas acuáticos. El objetivo de este trabajo fue evaluar la calidad de los bosques de ribera y las perspectivas de restauración del río Carrileufu, desde sus nacientes en lago Cholila hasta su desembocadura en lago Rivadavia, NO de Chubut. Se incluyeron diez tramos sobre el curso principal y dos ubicados en uno de sus afluentes, el río Pedregoso. Se realizó una caracterización física y ecológica a nivel ecosistémico y a escala de tramo, y se registraron variables ambientales, atributos de la comunidad vegetal y procesos geomorfológicos activos e inactivos en el entorno fluvial. Se aplicó el índice QBRp en doce tramos de 100 m de longitud, sometidos a uno o más usos de la tierra (i.e., plantaciones de exóticas, urbanización, actividad agropastoril, recreativo-turística). Con la información relevada como insumo, se aplicó un análisis multicriterio que permitió definir la factibilidad de la restauración y el manejo más adecuado para cada tramo del río. Los valores del índice QBRp variaron entre calidad de ribera intermedia a muy buena, sin tramos con calidad mala o pésima. Se observó una relación inversa entre la calidad de los bosques de ribera y la superposición e intensidad de usos. En cuanto a las perspectivas de restauración, tres tramos del río presentaron una factibilidad ´sencilla´, cuatro de ellos ´moderada´ y cinco ´difícil´, con distintos tipos de manejo indicados para su recuperación, que van desde la conservación/regeneración, restauración, restauración compleja/revegetación, hasta rehabilitación de los tramos más degradados.[Palabras clave: ambiente acuático, Carrileufu, estado ecológico, manejo, QBRp] A�������. Quality assessment and restoration perspectives of riparian forest in an Andean river from Patagonia, Argentina. The river banks are one of the most important aspects to quantifying and qualifying the ecological status of aquatic ecosystems. An evaluation of the quality of the riparian forests and the restoration perspectives of the Carrileufu river, from its sources in Cholila lake to its mouth in Rivadavia lake, NW of Chubut was raised. Two stretches of the tributary Pedregoso river were also included. A physical and ecological characterization was carried out at the ecosystem level and at the stretch level, registering environmental variables, plant community a�ributes and the active and inactive geomorphological processes in the river environment. The QBRp index was applied in twelve stretches of 100 m in length, subject to one or more land uses (i.e., exotic plantations, urbanization, agriculture, livestock, recreational-tourist activity). A multicriteria analysis was applied, with the information relieved as input, which allowed defining the feasibility of restoration and the most appropriate management for each stretch of the river. The values of the QBRp index varied between intermediate to very good river bank quality, without bad or bad quality; observ...

This work evaluates the consequences of anthropogenic pressures at different sections of a Patagonian mountain river using a set of environmental and biological measures. A map of risk of soil erosion at a basin scale was also produced. The study was conducted at 12 sites along the Percy River system, where physicochemical parameters, riparian ecosystem quality, habitat condition, plants, and macroinvertebrates were investigated. While livestock and wood collection, the dominant activities at upper and mean basin sites resulted in an important loss of the forest cover still the riparian ecosystem remains in a relatively good status of conservation, as do the in-stream habitat conditions and physicochemical features. Besides, most indicators based on macroinvertebrates revealed that both upper and middle basin sections supported similar assemblages, richness, density, and most functional feeding group attributes. Instead, the lower urbanized basin showed increases in conductivity and nutrient values, poor quality in the riparian ecosystem, and habitat condition. According to the multivariate analysis, ammonia level, elevation, current velocity, and habitat conditions had explanatory power on benthos assemblages. Discharge, naturalness of the river channel, flood plain morphology, conservation status, and percent of urban areas were important moderators of plant composition. Finally, although the present land use in the basin would not produce a significant risk of soil erosion, unsustainable practices that promotes the substitution of the forest for shrubs would lead to severe consequences. Mitigation efforts should be directed to protect headwater forest, restore altered riparian ecosystem, and to control the incipient eutrophication process.

Nous décrivons les appareils et la technique pour la préparation, la mise en circulation et le barbotage dans les réactifs aldéhydiques, de mélanges gazeux à proportions variées et bien déterminées d'ozone, d'oxygène et d'azote. Les concentrations en ozone ont été abaissées progressivement de 10−4 à 0; aux fortes dilutions en ozone, les mélanges étaient préparés avec un air préalablement désozoné par la chaleur dans un dispositif spécial.

A l'isopip6rit6none que nous n'avons encore pu isoler correspondent la y-atlantone et la sylvbcarvone de Wallach*). En outre, il semble que la cyclisation du citral ait livr6 l'isopip6ritho1, c'est du moins l'hypothkse qui a &ti. formu1i.e par Zritschel et Sch1121d15) _ , 1) XVIIe Communication: Helv. 25, 984 (1942:.