Differences in large instream wood between channelized and unchannelized agricultural headwater streams in the Midwestern United States

Authors: Smiley, Peter; GATES, ERIC - The Ohio State University

Submitted to: Discover Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2025
Publication Date: 4/28/2025
Citation: Smiley, P.C., Gates, E. 2025. Differences in large instream wood between channelized and unchannelized agricultural headwater streams in the Midwestern United States. Discover Conservation. 2. Article 17. https://doi.org/10.1007/s44353-025-00036-0.
DOI: https://doi.org/10.1007/s44353-025-00036-0

Interpretive Summary: Instream wood (i.e., sticks, logs, fallen trees, root wads, etc) is a critical habitat feature within streams. Many agricultural headwater streams in the Midwestern United States have been subjected to stream channelization that leads to the removal of instream wood. Quantitative information on the reductions of instream wood that occur within agricultural headwater streams as a result of channelization are lacking and needed to develop novel management strategies that are capable of increasing the ecosystem services provided by channelized agricultural headwater streams (i.e., drainage ditches). We assessed the diversity and the amount of instream wood within channelized and unchannelized agricultural headwater streams within a large Ohio watershed by conducting a small scale field study and through the retrospective analyses of a large scale instream wood database. Our field study and retrospective analyses quantified that stream channelization reduces the diversity and amounts of large instream wood within agricultural headwater streams. These results suggest that channelized agricultural headwater streams will benefit from watershed management strategies that increase the diversity and amount of instream wood.

Technical Abstract: The widespread use of channelization for agricultural drainage in the Midwestern United States has resulted in the occurrence of a large number of channelized agricultural headwater streams within the region. Stream channelization frequently results in the removal of instream wood that is a critical habitat feature in streams. Quantitative information on instream wood characteristics within channelized agricultural headwater streams and how they compare to unchannelized streams is lacking. We assessed the diversity, frequency of occurrence, and the amount of instream wood within channelized and unchannelized agricultural headwater streams within a large Ohio watershed by conducting a small scale field study and through the retrospective analyses of a large scale instream wood database from agricultural headwater streams. Our field study documented that the amounts of large instream wood in agricultural headwater streams in central Ohio was similar to the values observed in other Midwestern headwater streams. Our field study also quantified that the diversity and amounts of large instream wood was greater in unchannelized than channelized streams. Our retrospective analyses observed that instream wood diversity and percentage of sites with logs, root wads, and root mats were greater in unchannelized than recovering or recently channelized sites. Our results and others from the Midwestern United States quantify that stream channelization for agricultural drainage reduces the richness and amounts of large instream wood by at least two times that of the values observed in unchannelized headwater streams. These results suggest that channelized agricultural headwater streams may benefit from watershed management practices and strategies that increase the diversity and amount of instream wood within these degraded streams.