Forest Investment Account (FIA) - Forest Science Program
FIA Project Y062305

    Managing northern mixedwood stands to sustainably maximize productivity and minimize costs
Contributing Authors: Hawkins, Chris D.B.; Quinn, Orrin; Rogers, Bruce
Imprint: Prince George, B.C. : University of Northern British Columbia, 2006
Subject: Forest Investment Account (FIA), Forest management, British Columbia, Picea Glauca, Growth
Series: Forest Investment Account (FIA) - Forest Science Program
This project seeks to further our understanding of the dynamic interactions between white spruce and associated broadleaf competition in the Fort Nelson, Mackenzie, and Fort St. John TSAs. The primary objective) is to define broadleaf density (basal area) thresholds (temporal and spatial) that are deleterious to spruce establishment, growth and long term productivity. Such information will allow fine tuning of free growing guidelines in BC in order to optimize forest productivity, health, and diversity. Long-term timber supply is a major consideration in regenerating stands in BC. It is the goal of regulatory bodies to ensure a continued supply of timber for future generations to enjoy. Timber supply analyses conducted on an area are carried out using several assumptions. One of these is that regenerating stands are growing without impediment from non-crop vegetation (Anonymous 2005). Further, the establishment or retention of broadleaf trees within a stand may be desirable to provide a nurse crop, promote nutrient cycling, or to meet other resource objectives such as biodiversity or wildlife habitat. Finally, blanket guidelines to achieve healthy regenerating stands are not appropriate for a province as biologically diverse as BC. Benefits could be seen at the block level (micro) with an increased diversity in ecosystem function and stand structure, as well as at the landscape level (macro) with a wider distribution of stand type, habitat and biodiversity. Despite the establishment of free-to-grow guidelines, there remains limited quantitative information available on how these stand types develop during early seral stages. Management of aspen density, but not complete removal, may enhance the survival and growth of understory spruce (Wright et al. 1998, Comeau 2003, Newsome 2003, unpublished). There is also concern about birch-spruce mixtures: presently the maximum limit of deciduous stems is 1000 sph (Anonymous, 2000). This value may be low, particularly in stands that have received an earlier herbicide treatment (Doug Tofte, pers. com.). Work in birch-spruce stands in the sub boreal suggests that 3000 co-dominant sph of birch may not negatively impact spruce growth. The cost of brushing treatments to meet free growing guidelines represents the highest cost of silviculture activities (K. Szabo, pers. comm.). The Adams Lake Interfor Innovative Forest Practices Agreement (ALI-303) showed the cost of brushing birch from blocks planted to lodgepole pine was greater than the anticipated increase in stand value. This strongly suggests that an alternative to the current free-to-grow approach may be cost effective.
Chris Hawkins.
Related projects:  FSP_Y051305FSP_Y073305
Contact: Quinn, Orrin, (250) 960-5778,

Executive Summary (31Kb)

Updated August 16, 2010 

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