Spatial distribution of large wood jams in streams related to stream-valley geomorphology and forest age in Northern Michigan

Authors

  • Arthur E. L. Morris,

    1. School of Environment and Natural Resources, Ohio Agricultural Research and Development Center (OARDC), The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA
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  • P. Charles Goebel,

    Corresponding author
    1. School of Environment and Natural Resources, Ohio Agricultural Research and Development Center (OARDC), The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA
    • School of Environment and Natural Resources, Ohio Agricultural Research and Development Center (OARDC), The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691.
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  • Brian J. Palik

    1. Northern Research Station, USDA Forest Service, 1831 Highway 169E, Grand Rapids, MN 55744, USA
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    • The contribution of Brian J. Palik was prepared as part of his official duties as a US Government employee.


Abstract

Geomorphology at the scale of stream valleys influences smaller scale processes that give rise to spatially distributed patches, including large wood jams (LWJ) in streams. Understanding the spatial distribution of LWJ along streams with reference to large-scale geomorphology is valuable for understanding stream and riparian interactions, and may be critical for effective stream management and restoration. We surveyed the locations of LWJ along 18 stream segments within study areas defined by stream-valley geomorphology. The objective of this study was to test the prediction that LWJ in this system will be aggregated in areas defined by stream-valley geomorphology, but be randomly distributed at smaller scales. The spatial distribution of LWJ was analysed by a one-dimensional K-function analysis capable of detecting aggregated, random and segregated patterns at different scales. The prediction that LWJ aggregate in areas defined by stream-valley geomorphology was supported: LWJ aggregated at scales up to several kilometres in three streams. LWJ also was segregated at smaller scales in two of these streams; this was detectable when several stream valley segments were considered together. The prediction that LWJ would be randomly distributed at smaller scales was supported at most smaller scales for most streams. In fact, 40% of individual stream valley segments contained LWJ that were randomly distributed at all scales. Twenty-seven per cent of individual stream valley segments showed segregated LWJ distributions. Large-scale aggregation of LWJ evidences the need to select reference reaches that encompass several geomorphic patches at the scale of the stream valley. Segregated patterns of LWJ distributions evidence opportunities to better understand the relationships between hydraulic systems, material transport dynamics and riparian forests. Copyright © 2009 John Wiley & Sons, Ltd.

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