The current forest management practices that were being approved and implemented in each zone when the timber supply analysis was initiated are briefly described below. The Cranbrook Forest District Riparian Management Zone Guidelines and the Cranbrook Forest District Interim Old Growth Strategy outline some of the current practices in the Cranbrook Timber Supply Area.
• Basic silviculture — British Columbia laws require areas that are harvested and expected to produce timber in the future must be reforested with ecologically acceptable species within a specified time frame (three to six years was used in the analysis). The most common silvicultural practice is to clearcut harvest, allow for natural regeneration and/or plant, then brush and weed if needed.
• Incremental silviculture — Juvenile spacing, pruning and commercial thinning are practised on some of the most productive sites in the Cranbrook Timber Supply Area.
• Unsalvaged timber losses — Timber losses due to wildfire, insects, diseases and blowdown are minimized as much as possible. Based on the best available information for the past 10 years, unsalvaged losses are estimated to be 139,000 cubic metres per year from the following sources:
• insects (mainly mountain pine and spruce bark beetles): 77,000 cubic metres per year
• diseases: 11,000 cubic metres per year
• wildfire, windthrow and snow damage: 51,000 cubic metres per year
• Riparian areas - The Cranbrook Forest District Riparian Management Zone Guidelines include the following requirements to provide protection and maintenance of water quality, aquatic habitats, wildlife habitats and biodiversity:
• buffers where machinery is not permitted
• reservation of deciduous trees
• restrictions on cutblock size
• minimum area of unlogged forests between cutblocks
• minimum height of regenerated forests in cutover areas before adjacent timber can be harvested (green-up height)
• maximum area that can be harvested and be below the green-up height at any one time
• maintenance of a minimum amount of mature forests
• Wildlife/biodiversity - Current wildlife management requirements include maintaining a specified number of dead trees, larger trees and clumps of timber within cutblocks to provide wildlife habitat.
• Harvest ages - Minimum harvest age is defined as the time it takes for forests to grow to harvestable size. The minimum harvest ages used in the timber supply analysis range from 50 to 200 years based on trees species, ecological considerations and current harvesting practices.
• Soil conservation - Harvesting layout follows provincial and regional guidelines. For the timber supply analysis, 4.5 per cent of the timber harvesting land base was deducted for existing roads and landings that are no longer productive. To account for future roads and landings, the remaining land base was reduced by 4.5 per cent after the first harvest.
