For the timber supply analysis, Forest Service staff divided the timber harvesting land base into management zones by grouping areas where similar integrated resource management practices are implemented. This approach permits an analysis of the different types of forests and the range of practices in the Lakes Timber Supply Area. The area in each zone was estimated from existing inventories and guidelines for integrated resource management in the timber supply area. Site specific practices implemented in any one area may differ from the practices used in the analysis for each zone.
Figure 6 illustrates the area within each management zone.
Figure 6 Area of each management zone in the timber harvesting land base
Forest cover requirements have been defined for each zone to permit analysis of the integrated resource management guidelines that were being implemented when the timber supply analysis was initiated. These requirements establish:
• the maximum amount of forest that can be younger than a certain age at any time, to ensure harvesting does not become overly concentrated in a zone
• a minimum area that must be covered by forests older than a certain age.
The forest cover requirements for each management zone are described below.
• Visually sensitive zones (156,519 hectares) —important viewscapes from most lakes and from Highways 16 and 35. The management objective is to maintain sufficient forest cover to limit visible changes in the landscape. Two zones have been identified based on visual quality objectives:
• moderately sensitive (partial retention zone) (131,641 hectares) — at least 88 per cent of the area must have trees at least 6.5 metres tall at any one time
• very sensitive (retention zone) (24,878 hectares) — at least 98 per cent of the area must have trees at least 6.5 metres tall at any one time
• Wildlife winter range (34,420 hectares) — areas mapped as prime habitat for moose and deer. At least 35 per cent of the timber harvesting land base within this zone must have forests older than 100 years at any time. A maximum of 33 per cent of the timber harvesting land base is permitted to have forests less than three metres tall at any time.
• Caribou corridor ( 29,035 hectares ) — a migration corridor used by the Tweedsmuir Entiako caribou herd to travel between summer range and calving areas in Tweedsmuir Park and their winter range south of Tetachuk Lake. Forest cover requirements in this zone are based on a recently completed Integrated Resource Management Plan and current understanding of the forest conditions that permit caribou travel. Lodgepole pine forests must have fewer than 2,000 trees per hectare at least 10 metres tall. In addition, no more than 12.5 per cent of the timber harvesting land base is permitted to have trees less than three metres tall at any time.
• Riparian zone (16,455 hectares) — individual riparian areas which are larger than 100 hectares are included in this zone. A minimum of 50 per cent of the timber harvesting land base must be maintained in forests at least 120 years old in this zone. Adjoining areas can only be harvested if regenerated forests are at least five metres tall.
• Sutherland Valley ( 4,648 hectares ) — an area deferred from timber harvesting in a Local Resource Use Plan approved in 1992. For the timber supply analysis it was assumed no harvesting would occur for 10 years.
• Integrated resource management zone (416,939 hectares) — the remaining timber harvesting land base not assigned to another zone. This zone is scheduled to be harvested in three entries so at any given time, no more than 33 per cent of the timber harvesting land base is permitted to contain forests less than three metres tall.
