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Littoral and Shoreline Wood in Mid-continent Great Rivers (USA)
Citation:
ANGRADI, T. R., D. L. TAYLOR, T. M. JICHA, D. W. BOLGRIEN, M. S. PEARSON, AND B. H. HILL. Littoral and Shoreline Wood in Mid-continent Great Rivers (USA). River Research and Applications. John Wiley & Sons Incorporated, New York, NY, 26(3):261-278, (2010).
Impact/Purpose:
This estimate of mean wood abundance for what could be considered least disturbed riparian and shoreline conditions is relevant for great river bioassessment and management.
Description:
Less is known about the ecology of wood in great rivers than in smaller lotic systems. We used a probability survey to estimate the abundance of littoral and shoreline wood along the mid-continent great rivers of the United States: the Missouri, Upper Mississippi, and the Ohio Rivers in 2004 2006. We counted wood pieces >0.3 m in diameter from a zone between the bank full level out into the river 10 m. We categorized wood according to its origin and function as “beached” (transported from upriver but not providing aquatic habitat), “wet” (origin unknown and providing aquatic habitat; includes snags), and “anchored” (attached to the bank at its current location and providing aquatic habitat). We counted 5900 pieces of wood at 447 sites across rivers. About 56% of pieces were beached, 30% were wet, and 14% were anchored. Overall mean abundance of wood was 2.6 pieces of wood 100m-1 of shoreline (approximately 3.0 m3100m-1) The distribution of wood was highly patchy; coefficients of variation in wood abundance at the river scale were >100%, and the abundance of wood was not spatially auto-correlated along rivers. There was more wood along the Upper Mississippi River (3.3 pieces 100m-1) than elsewhere (<2.4 pieces 100m-1). The mean abundance of wood on the Ohio River decreased significantly between the 2004 and 2005 survey period due to high flows. Longitudinal patterns in wood abundance were weak. The abundance of beached wood increased slightly downriver on the Missouri and Ohio. There was less anchored and wet wood along shorelines protected by revetment (e.g. rip rap). There was generally more wood along shorelines where the riparian land use was characterized as forest rather than agriculture or developed. Mean abundance of wood along forested, un-revetted shorelines was about 4 pieces 100m-1 of shoreline (=80 pieces km-1 of river). This estimate of mean wood abundance for what could be considered least disturbed riparian and shoreline conditions is relevant for great river bioassessment and management.