Forest Investment Account

Abstract of FII Project R02-33

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Modelling the Effects of Large Debris

Author(s): Rosenfeld, Jordan (BC Ministry of Water, Land, and Air Protection)
Subject: Forestry
Series: Forest Investment Account (FIA) - Forest Science Program


Large Woody Debris (LWD) recruiting to streams and rivers from the riparian forest has a major influence on channel structure and fish habitat throughout British Columbia and the Pacific Northwest. Harvest of riparian forest leads to changes in recruitment of LWD with subsequent long-term effects on both channel structure and fish abundance over decades to centuries. At present, long-term effects of current riparian management practices are unknown. The objective of this project is to develop a model linking riparian management (e.g. buffer width) to LWD input rates, small stream channel structure, and abundance of juvenile anadromous cutthroat trout and coho salmon, and is a direct extension of previous forestry-related research in coastal B.C. streams (Rosenfeld and Parkinson 1995, Rosenfeld et al. 2002, Rosenfeld and Boss 2001, Rosenfeld et al. 2000, Rosenfeld 2000). This model will serve as a management tool for coastal B.C. forest planning and should be applicable outside coastal B.C. when appropriate model parameters become available for other regions.
The primary goal of the first year (2001-2) of this 3-year project was development of the basic model structure. The primary goal of Year 2 (2002-3) was to have begun testing the impacts of different riparian management scenarios, but model development and programming has taken longer than expected because of the complexity of the model, and has taken up most of Year 2. We are now in the process of fitting the model to forest diameter, biomass, and growth rate parameters for Coastal Western Hemlock data for B.C.. Because of the delayed development of the primary model, all outcomes and deliverables for the rest of the project will be delayed by 6 to 12 months, but most identified deliverables will still be produced in Year 3. Nevertheless, the project may have to be extended to finish several of the originally proposed deliverables (e.g. modeling the long-term trajectory of habitat and fish populations at 30 representative cutthroat trout streams). The overall outcomes, impacts, and end-users of the project remain unchanged.

For further information, please contact Jordan Rosenfeld, BC Ministry of Water, Land, and Air Protection (

Updated September 08, 2005 

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