In the absence of wildfire, forest stands in the Sub-Boreal Spruce biogeoclimatic zone (SBS) of British Columbia (B.C.) can achieve great age, upwards of 340 to 440 years. The frequency of stand-level disturbance (by wildfire, bark beetles, and windthrow) makes this old-growth resource quite rare, occupying less than approximately 3% of some sub-zones. This rarity requires special management considerations.
Recent studies have investigated the long-term dynamics of forest stands in the SBS, and this work was used to develop a score-card for evaluating the old-growth status of interior spruce stands in one sub-zone of the SBS. Eleven stand attributes are used in this rating system, including minimum values for stand age (175 years), total snag bole volume (80 m3/ha), and large log (>1.0 m3 per piece) density (100 per ha).
It is suggested that stands with structural or functional old-growth attributes are worthy of identification and protection. Some of these stands could be partially cut without technically compromising old-growth values, if their critical attributes (as identified in the score-card) can still be retained. More appropriate solutions over the landscape include generally longer rotations, extended rotations for some stands, and the protection of old-growth features in small patches retained within cut-blocks. Numerical approaches are described which can assist in the orderly development of a sub-boreal landscape while still retaining old-growth values.
Citation: Abstract of a paper presented at the Second International Workshop on Disturbance Dynamics in Boreal Forests, held in Rouyn-Noranda, Quebec, Canada, August 26-30, 1996. Proceedings published in the Journal of Vegetation Science. A simplified version of this paper is available as Forest Sciences Extension Note #14, from the B.C. Ministry of Forests, Postal Bag 5000, Smithers, B.C., Canada V0J 2N0.
* Author for correspondence: P.O. Box 3398, Smithers, B.C., Canada V0J 2N0. Tel. 250-847-0278, Fax. 250-847-0279, E-mail symbios@mail.netshop.net