Forest Investment Account (FIA) - Forest Science Program
FIA Project Y062170

    Functional large woody debris in small streams: what is it?
Imprint: [S.l.] : [BC Forest Service], 2006
Subject: Forest Investment Account (FIA), Forest management, British Columbia, Coarse woody debris
Series: Forest Investment Account (FIA) - Forest Science Program
A specific objective of riparian management prescriptions (amongst several) is to maintain a supply of large woody debris (LWD) from the riparian area to the stream. This usually involves designation of a certain portion of the riparian area as either a riparian management zone (allowing some forest harvesting) or a riparian reserve zone (restricting all forest harvesting). In some jurisdictions this may also involve some form of variable retention of the riparian canopy. However, gaps in our knowledge prevent us from designing effective prescriptions. In particular, we lack an operational and physically meaningful definition of the term 'LWD' (specifically, how do we define 'large'?). Despite the common utilization of scaling relations in fluvial geomorphology, wood characteristics have always been based on the absolute size of a log with little consideration to the size of the channel. The objectives of this research are to develop a process-based definition of LWD scaled to the size of a channel. This definition will then be used to establish best management practices for the supply of functional LWD (log length and diameter) from riparian areas adjacent to small riffle-pool and step-pool streams (generally, bankfull widths ranging from 1 to 20 m). This includes specification of the width and retention level of a buffer for each major forested biogeoclimatic zone in British Columbia. Development of science-based riparian management prescriptions can both improve stewardship of fish values and forest resources by establishing effective buffer widths, and can optimize production and value from timber resources by not unduly restricting access to timber. This project was based entirely on data collected over several previous years, funded by FRBC and FIA; the project analyzed the existing data base. Analysis of data included the use of a simulation model and results are recommendations are geographically specific; results are applicable to all regions of the province. Two reports have been written (see attached). The first report deals with log scaling issues and we intend to submit it to a primary journal for publication. The second considers wood recruitment to streams and includes recommended riparian buffer widths. We intend to publish this as a Forest Service Land Management Handbook to be used by operational staff. Our work has been delayed due to a protracted review process. Because some of the results are potentially controversial (see below), we feel it to be prudent to get a careful review of the work prior to submission to the publishers. Once we are confident with the results we will submit the reports to the journals and they will then receive a second review. Of the three that agreed to review the documents only one (Dr. Rice, see attached) has provided comments to date. All comments received were constructive and should not alter the fundamental aspects of the reports. We are now incorporating his comments. Repeated attempts to have the other reviewers complete their work have been made and more will be made. We only recently received the comments from Dr. Rice but now that it is available we can give a deadline to the others and proceed on the basis of a single review, if necessary. The reviewers were told that these are draft versions and that several minor parts will be added to the reports during revision completion. As stated in the above, parts of the results included in the reports are potentially controversial. This is because buffer widths, sufficient to maintain the physical integrity of a stream channel, are reported. (Note: we do not consider any of the other attributes attributed to riparian vegetation, such as biological (insects, food, wildlife, etc.), recreation or climatic factors). In some cases the recommended buffer widths are less than those that have commonly been applied in the past; this may be of concern to the federal Department of Fisheries and Oceans whereas this may be seen as a benefit to forest managers. Therefore, we request that these reports not be released until all levels of review are complete.
Dan Hogan.
Related projects:  FSP_Y051170
Contact: Hogan, Dan, (604) 222-6752,

Updated August 17, 2010 

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