Forest Investment Account

Abstract of FIA Project Y051073

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Understanding and predicting snag and CWD dynamics in Sub-boreal Spruce and Engelmann Spruce - Subalpine fir forests

Author(s): DeLong, Craig
Imprint: Vancouver, B.C. : B.C. Ministry of Forests, 2005
Subject: Forest Investment Account (FIA), Coarse woody debris
Series: Forest Investment Account (FIA) - Forest Science Program


Forest management activities influence the future distribution of 'structural attributes' in forests, important for future biodiversity. To assess the potential impacts of (i) rate of harvest; (ii) pattern of harvest and (iii) dead wood management strategies on dead-wood dynamics, we developed a spatially-explicit landscape dynamics model which includes sub-models for snag removal, snag and CWD dynamics, harvesting activities and access management. The model assesses changes in snag density and downed wood volume and configuration across landscapes over a time horizon of several decades in response to different harvesting patterns, and road access. We parameterized and implemented this model for a wet hybrid spruce subalpine fir forested landscape east of Prince George, British Columbia. The modelling approach taken allows the capture of relatively fine-scale spatial variation in site type, spatial effects of management and stratification of decay rates and wildlife value for different size classes and tree species groups. Unique elements of the model include the capture of snag falling resulting from safety regulations, the capture of stump production and dynamics, and significant flexibility for altering the model for tree species, size classes of trees, number and length of decay states. It also can capture management practices at the landscape (e.g., harvest rate, road building, patch size distribution) and the stand level (e.g., variable retention, stumping). Preliminary results indicate that there is cause for concern in regards to deadwood supply, in particular CWD, over the next rotation. The model developed will be invaluable for testing the ability of new deadwood management practices to alter the decline in CWD supply forecast.

For further information, please contact Craig DeLong, BC Ministry of Forests (

Updated September 08, 2005 

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