Residuos leñosos de gran tamaño en un torrente de la Cordillera de Los Andes, Chile: su funcionalidad e importancia

The study analyzed amounts, characteristics and morphological impact of Large Woody Debris (LWD) in Tres Arroyos torrent of the Chilean Southern Andes draining an old-growth forested basin. All woody debris pieces greater than 10 cm in diameter and 1 m in length were surveyed along a 1.5 km-long stream section presenting a general step-pool/cascade morphology. The total amount of large woody debris within the fluvial corridor was on average 1,500 m3/ha, very high value comparable only to data from old-growth forested basins in the Pacific Northwest of North America. Around two thirds of LWD volume were found in accumulations while half of the LWD elements were located on the active floodplain. As much as 83% of the LWD pieces showed signs of in-stream transport, 13% were directly associated to natural tree falls, and the remaining to landslides and bank erosion. Different types of log-jams were observed, some heavily altering channel morphology (log-steps and valley jams), others just lining the channel edges (bankfull bench jams). The percentage of log-steps over the total number of steps is around 22%, whereas the elevation loss due to LWD (log-steps and valley jams) was 27% the total potential energy. Finally, 2,000 m3 of sediments were estimated to be stored in the main channel behind LWD structures, corresponding to approximately 150% of the annual basin sediment yield

Movilidad y reclutamiento de material leñoso de gran tamaño en dos cauces de la Cordillera de la Costa de Chile

In-stream large wood mobility was studied in segments of the main channels of Vuelta de Zorra and Pichún catchments, located in the Coastal Mountain Range, Chile. Statistical significant relationships were found only between bankfull channel width and dependent variables associated to some large wood characteristics measured in the channel reaches. This would indicate that large wood length, and not diameter, would regulate the mobility of the wood pieces during high flows. After the winter season of 2009, the 12 and 6.5 % of the wood elements were mobilized in Vuelta de Zorra and Pichún, respectively. The lower percentage in Pichún would be associated to the lower bankfull width/mean piece length ratio. A statistical non-significant trend was found between mobilized distance and piece length/mean bankfull width; indicating that distance decreased with increased dimensionless piece length. Large wood mobility in the two channels was associated to normal peak flows and could be considered as a minimum mobility rate at annual level. The recruited wood volume was higher than the exported wood volume in both segments, therefore the study period can be considered as an in-stream large wood stocking-period

Reach scale ecologic influence of in-stream large wood in a Coastal Mountain range channel, Southern Chile

The ecologic influence of in-stream large wood (LW) was evaluated at reach scale in a third-order channel located in the Coastal Mountain Range, southern Chile. The tested hypotheses were that Coarse Particle Organic Matter (CPOM) retention is higher and benthic macro-invertebrates are more diverse in channel reaches storing higher volumes of LW. Three LW-low-volume reaches (mean LW volume of 8 m³ 100m-1 of reach channel length; plane bed morphology) and three LW-high-volume reaches (mean volume 262 m³ 100m-1; forced pool riffle bed morphology) were selected within a 1557 m-long segment of the study channel. CPOM retention was inferred from the difference between the number of leaves collected in the downstream end of each reach and the leaves introduced in the upstream end. Mean CPOM retention was 72 and 90% among LW-low and high volume reaches, and showed a positive correlation (R = 0.61) with LW volume. Macro-invertebrates were more diverse and abundant in LW-high-volume reaches and the richness was twice than in LW-low-volume reaches. Bray-Curtis similarity index was low (40%) between LW-high and low volume reaches, while it was high (> 60%) among LW-low-volume reaches. Results confirm the hypothesis that OM retention and benthic macro-invertebrate diversity and abundance were higher in high LW volume reaches. The higher diversity and abundance of macro-invertebrates associated with LW accumulations confirm that logjams constitute a biotope that offers shelter and food. These results can guide the assessment of environmental impacts of stream intervention and restoration projects. The study was undertaken within the framework of Project Fondecyt 1110609. La influencia ecológica de la madera en el cauce (LW) fue evaluada a nivel de tramo en un canal de tercer orden localizado en la Cordillera de La Costa, sur de Chile. Las hipótesis planteadas fueron que la retención de Materia Orgánica Particulada Gruesa (CPOM) es mayor y que la diversidad de macro-invertebrados bentónicos es también mayor en tramos que almacenan una mayor cantidad de LW. Tres tramos con bajo volumen de LW (volumen medio de 8 m³ 100m-1 de largo de tramo; morfología de lecho plano) y tres tramos con alto volumen de LW (volumen medio de 262 m³ 100m-1; morfología de lecho de rápidos y pozas) se seleccionaron dentro de un segmento de 1557 m de largo en el canal estudiado. La retención de CPOM fue inferida de la diferencia entre el número de hojas recogidas al final de cada tramo y las hojas introducidas al canal en el extremo de aguas arriba. La retención promedio de CPOM fue 72 y 90% en tramos con bajo y alto volumen de LW, y mostró una correlación positiva (R = 0,61) con el volumen de LW. La diversidad y abundancia de macro- invertebrados fuero mayor en tramos con mayor volumen de LW y la riqueza fue el doble que en tramos con bajo volumen de LW. El índice de similaridad de Bray-Curtis fue bajo (40%) entre tramos con alto y bajo volumen de LW, mientras que fue alto (> 60%) entre tramos con bajo volumen de LW. Los resultados confirman la hipótesis que la retención de CPOM y la diversidad y abundancia de macro-invertebrados bentónicos fueron mayores en tramos con mayor volumen de LW. La mayor diversidad y abundancia de macro-invertebrados asociadas con acumulaciones de LW confirman que los diques de madera constituyen un biotopo que ofrece protección y alimento. Estos resultados pueden guiar la evaluación de los impactos ambientales de proyectos de intervención o restauración de cauces. Este estudio fue desarrollado en el marco del Proyecto Fondecyt 1110609

Cross-cultural adaptation of the Brazilian version of the Impact of Events Scale-Revised (IES-R)

The Impact of Events Scale-Revised (IES-R) is used to screen for post-traumatic stress disorder (PTSD). The aim of this study was to assess the cross-cultural adaptation of the IES-R. The scale was translated into Brazilian Portuguese and culturally adapted. Reliability and validity were evaluated in 45 individuals divided into three groups of 15 (without PTSD, with PTSD, and treated for PTSD). Reliability was evaluated using intraclass correlation coefficient - ICC and Cronbach's alfa. Discriminant validity was evaluated by comparing mean IES-R scores in the three groups. The area under the ROC curve (AUC) was evaluated to determine cut-offs with higher sensitivity (s) and specificity (e) using the clinical interview (DSM-IV) as reference. The IES-R showed good reliability (ICC = 1; alfa from 0.75 to 0.93). The mean IES-R scores (p < 0.05) and ROC curve had good discriminant validity for a cut-off of 5.6 (s = 0.80, e = 0.70 and AUC = 0.81). The Brazilian version of IES-R showed good properties and can be a useful screening tool for PTSD.A Escala de Impacto do Evento - Revisada (IES-R) é utilizada no rastreio de transtorno de estresse pós-traumático. O objetivo do estudo foi avaliar a adaptação transcultural da IES-R. Realizou-se a tradução e adaptação da escala para o português do Brasil. Confiabilidade e validade foram avaliadas entre 45 sujeitos distribuídos em 3 grupos de 15: sem transtorno, com transtorno e tratados para transtorno. A confiabilidade foi avaliada pelo Coeficiente de Correlação Intraclasse (ICC) e pelo alfa de Cronbach (α). A validade discriminante foi calculada pela comparação dos escores médios de IES-R nos 3 grupos. A área sobre a curva ROC (AUC) foi avaliada para determinar os pontos de corte com maiores sensibilidade (s) e especificidade (e), utilizando-se a entrevista clínica (DSM-IV) como referência. A IES-R exibiu boa confiabilidade (ICC = 1; α entre 0,75 e 0,93). Os escores médios da IES-R (p 0,05) e a curva ROC mostraram boa validade discriminante para o ponto de corte de 5,6 (s = 0,80, e = 0,70 e AUC =0,81). A versão brasileira da IES-R apresentou boas propriedades e mostrou-se eficiente no rastreio de transtorno de estresse pós-traumático.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP, EPMSciEL

Transferability Of Mesohabitat Suitability Criteria In Northern Italy

In the framework of water resources planning and management, the MesoHABSIM (MesoHABitat SImulation Model) approach demonstrated high potential to assess suitable environmental conditions for freshwater fish species. In the present study, the transferability capabilities of mesohabitat suitability criteria were evaluated in nine streams across Northern Italy. In particular, the Random Forest (RF) technique was used to calibrate and validate suitability criteria for adult and juvenile life stages of brown trout (Salmo trutta), marble trout (Salmo marmoratus), bullhead (Cottus gobio) Italian barbel (Barbus plebejus), and Italian vairone (Telestes muticellus). Presence/absence binary models were calibrated at the mesohabitat scale (i.e., the geomorphic unit scale) using field data collected in reference sites, selected for their natural hydro-morphological conditions and habitat characteristics. Model transferability tests were performed in streams located in different regions within the distribution area of the fish and not included in the model calibration dataset. Predictive capacities of the models were very good in terms of accuracy (ranging from 75% to 82%) and true skill statistic (ranging from 52% to 75%). The high predictive performances can be related to (i) the use of an ecologically relevant spatial resolution (mesohabitat) to predict fish presence, (ii) a robust and adequate hydro-morphological characterization of the analyzed geomorphic units, and (iii) the large number of mesohabitat descriptors provided by the MesoHABSIM approach. Results showed that mesohabitat suitability criteria based on RF can be considered transferable among streams located in different regions of Northern Italy, especially when river channels are characterized by similar hydro-morphological characteristics

How do geomorphic characteristics affect the source of tree water uptake in restored river floodplains?

Alpine rivers and their floodplains have been highly modified by human activities during the last decades. River restoration projects aim to counteract these negative impacts and to restore ecosystem services provided by riparian habitats. We studied two recently restored river sites in the Ahr/Aurino and Mareit/Mareta Rivers (Italian Alps) to investigate how geomorphic conditions, soil moisture, and groundwater level affect the source of water used by grey alder (Alnus incana (L.) Moench). We compared the isotopic composition (δ2H) of tree sap at different locations (low terraces formed during bed incision and recent floodplains formed after restoration) with that of potential water sources, that is, groundwater, soil water, and rainfall. The monthly variation in the isotopic composition of rainfall was reflected in both shallow and deeper soil water, as well as in the isotopic composition of sap. The redistribution of precipitation and groundwater in the soil differed between the post-restoration floodplain sites and the post-incision terraces, leading to a different relation between the sap water, soil water, and groundwater isotopic composition. The results show that transpiration of A. incana trees growing on recent floodplains is mostly supported by stream-fed soil water, whereas trees growing on terraces mainly use precipitation-fed soil water. These marked, morphology-related differences in the source of transpiration water of grey alder highlight how channel degradation still affects the ecohydrological processes in Alpine fluvial corridors. Nonetheless, large restoration interventions—in terms of channel widening—can enable the self-formation of new floodplain areas characterized by stream water-fed riparian ecosystems

Acumulaciones de detritos leñosos en un cauce de montaña de Tierra del Fuego: análisis de la movilidad y de los efectos hidromorfológicos

This work reports on the geomorphic role of large wood pieces and jams in a third order mountain stream located in Southern Tierra del Fuego (Argentina), and draining an old-growth nothofagus forested basin not influenced by beaver damming activity. Even if the in-stream number of wood pieces (2,300) is comparable to that observed in other climatic areas, the slow growth of the nothofagus forest causes a lower wood abundance in terms of volumetric load (121 m3 ha–1). Due to the relatively small dimensions of the large wood pieces located inside bankfull edges (83% of the total surveyed pieces), almost the 70% of them demonstrated to have been transported by runoff and 6% derived from bank erosion or landslides. Wood jams exert a significant influence on the channel morphology, being responsible for the creation of 30% of pools. The geomorphic influence of LW jams is also exerted by a considerable sediment storing capacity (about 1,750 m3). The LW-forced pool volume is strongly and positively correlated to the height of the LW jam. The results confirm that dead wood pieces, especially when organized in jams, play an important geomorphic role also in sub-Antarctic streams. The amount of large wood pieces quantified in the study site represents reference values for the assessment of the geomorphic effects of beaver activity in other Tierra del Fuego streams