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Publication Title: Long-term dynamics of large wood in a third-order Cascade mountain stream [Abstract]
Year: 2000 Publication Type: Abstract
H. J. Andrews Publication Number: 2843
Citation: Gregory, S. V.; Ashkenas, L. R.; Wildman, R. C.; Meleason, M. A.; Lienkaemper, G. A. 2000. Long-term dynamics of large wood in a third-order Cascade mountain stream [Abstract]. In: International conference on wood in world rivers; 2000 October 23-27; Corvallis, OR. Corvallis, OR: Oregon State University: 95.
Online PDF: http://andrewsforest.oregonstate.edu/pubs/pdf/pub2843.pdf
Abstract: Since 1985, we have been studying input, storage, decomposition and redistribution of large wood in 750 m of old-growth forest and 300 m of 30 year-old clearcut in Mack Creek, Oregon. Within this 1.1 km section of stream, all pieces of large wood (> I in long, > 10 cm diameter) arc tagged and inventoried annually. Data collected include dimension, location, geomorphic position, and decay. Densities of large wood in the old-growth reach are 0.24 pieces/m2, with volumes of 0.08 m3/m2. Densities and volumes in the clear -cut were significantly lower. Most of the wood was found in accumulations of three or more pieces; in the old-growth 29% were in full-channel-spanning jams. The long-term nature of the study has allowed us to measure rates of input, fragmentation and movement. Recruitment of wood to both channel and floodplain was highly variable, and more closely related to climatic events(windstorms, snowfall) than to discharge events. Rates of in-channel movement were generally low (<1%) in any given year, but during a 35-year flood (1996) 11% of the logs in the old-growth and 25% of those in the clearcut moved >I0m. All pieces of wood that moved during the period of record were less than the width of the active channel, and most pieces that moved more than 300 m were less than 2 m in length. The interaction between channel geomorphology, hydrology and wood dimension determines overall dynamics of large wood in riverine ecosystems.
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