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Where does the river transport wood?
Longitudinal change in woody debris over a forested channel network
Amy Nicoll, M.Sc. CandidateSupervised by Lori Daniels and Marwan Hassan
Outline• Context and objectives• Study sites• Methods
• Stream dimensions• Wood survey
• Results• Stream characteristics• Changes in position class• Change in decay class• Proportion involved in logjams
• Next steps
Introduction Methods Results Next Steps
Woody debris in streams
Creates pools and changes flow
Regulates nutrient transportProvides habitat for fish
Influences sediment transport
Image: Steve Adams 2009
Introduction Methods Results Next Steps
Objectives
1. Identify zones of wood transport over a small stream network
2. Quantify changes in wood characteristics and functions associated with transport initiation
3. Compare wood residence time in transported and non‐transported wood regimes
Introduction Methods Results Next Steps
Study sites: Wigwam Creek
Introduction Methods Results Next Steps
Reach characteristics
• 14 reaches were selected over a range of drainage areas
• All sites had mature spruce riparian forest
• Length proportional to stream width (50x width)
Introduction Methods Results Next Steps
Reach characteristics
• Length proportional to stream width (50x width)• Width ranged from 0.1 to 8.6m
• Length ranged from 30 to 250m
Introduction Methods Results Next Steps
Stream Measurements• Stream dimensions measured every 2x stream width
• Local stream morphology and sediment size noted
• Morphological influence of wood recorded
Introduction Methods Results Next Steps
Woody debris survey
Introduction Methods Results Next Steps
Stream Dimensions
Introduction Methods Results Next Steps
Downstream abundance of woody debris
1885 pieces of wood were surveyed.
Introduction Methods Results Next Steps
Small streams Medium Larger
Recruitment + TransportRecruitment
Downstream concentration of woody debris
Introduction Methods Results Next Steps
Small streams Medium Larger
Downstream change in decay class
Introduction Methods Results Next Steps
Downstream change in position
Introduction Methods Results Next Steps
Proportion of wood in log jams
Introduction Methods Results Next Steps
Summary• Wood abundance may point to significant transport
beginning around 10km2
• Wood is predominantly fresh or very rotten upstream, and transitions to moderate decay downstream
• Wood gradually moves into “later stage” position classes
• Jams appear downstream of 6km2
Introduction Methods Results Next Steps
Upcoming analyses
• Analyze patterns of wood distribution• This will better identify wood jams (clusters) and therefore, locations of wood transport
• Examine downstream changesin function and size classes
• Compare time since death distributions between sites using tree ring analysis of logs
Introduction Methods Results Next Steps
Acknowledgements