LW jams in a mountain stream of Tierra del Fuego: piece movement and hydro-morphological effects analysis

• Published in: Bosque (Valdivia)
• Main Authors: Mao, Luca, Burns, Sarah, Comiti, Francesco, Andreoli, Andrea, Urciuolo, Adriana, Gaviño-Novillo, Marcelo, Iturraspe, Rodolfo, Aristide Lenzi, Mario
• Format: Article in Journal/Newspaper
• Language: Spanish
• Published: Universidad Austral de Chile, Facultad de Ciencias Forestales y Recursos Naturales. 2008
• Subjects: morfología de ríos; transporte de troncos; resistencia al flujo; retención de sedimentos; large woody debris; channel morphology; logs transport; flow resistance; sediment retention; Antarctic; Argentina; Esperanza; Antarc*; Tierra del Fuego
• Online Access: http://revistas.uach.cl/index.php/bosque/article/view/5798; https://doi.org/10.4067/s0717-92002008000300003

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. Se analizaron los volúmenes de material leñoso y las tipologías de acumulaciones observadas en el cauce del torrente Buena Esperanza, uno de los pocos cursos de agua de Tierra del Fuego (Argentina) no afectado por la presencia de castores. Aunque el número de piezas leñosas medidas en el cauce (2.300 elementos) fue comparable a lo reportado en otras áreas geográfica-climáticas, se estimó una menor abundancia en términos de volumen total de detritos leñosos (121 m3 ha–1) debido al lento crecimiento del bosque de Nothofagus spp. en estas latitudes. El 83% de los detritos leñosos se localizó dentro del canal activo, del cual el 75% presentó señales de haber sido ...