Assessing the relative quality of old-growth forest: An example from the Robson Valley, British Columbia

Forest planners in British Columbia (Canada) are required to identify forests suitable for designation as Old-Growth Management Areas. However, the tools currently in use lack the ability to identify appropriate stands. In 2000, we examined the ecological attributes of older forest in the Robson Valley Forest District in east-central British Columbia. The purpose was to determine the old-growth habitat value of stands of different age classes and to develop field procedures for assessing the relative old-growth quality of stands. We examined the relationships between stand age (both photo-interpreted and field-estimated) and attributes normally associated with old forest; in particular, we evaluated the relationship between stand age and functionally important tree and coarse woody debris configurations. Results from a representative portion of our study identified several attributes that were generally more abundant in older stands. The results also demonstrated that stands less than 140 years old have poorly developed old-forest habitat attributes, whereas these attributes are consistently well developed in stands greater than 140 years old. Also, the significance of these same attributes increases only slightly with increasing stand age. We created a rank scoring system to help forestry practitioners assess old-forest stands, particularly in the Interior Cedar-Hemlock biogeoclimatic zone, in terms of their value as old-growth wildlife habitat.