The integrated resource management practices that are implemented in the timber supply area are briefly described below.
• 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 (see TSAR page 57 for more details). The most common silvicultural practice is to harvest; then, if necessary, prepare the site for reforestation; reforest by planting with a mix of species or by relying on natural regeneration; and control competing vegetation. In the timber supply analysis it was assumed that harvested areas would be restocked within four years of harvesting.
• Forest health and unsalvaged losses — Losses of timber to fire, wind damage, insects and disease are minimized, and attempts are made to salvage timber that is damaged. Annual losses of timber not expected to be salvaged are estimated to average 70,428 cubic metres per year from the following sources:
• wildfire - 33,110 cubic metres
• disease - 22,560 cubic metres
• wind damage - 8,700 cubic metres
• insects - 6, 058 cubic metres
The estimated losses to wildfire and disease are relatively high because the steep, mountainous terrain in the area makes it difficult to salvage damaged timber.
• Harvestable ages — Minimum harvestable age is defined as the time it takes for stands to grow to harvestable size. The minimum harvest ages used in the timber supply analysis vary by tree species and site productivity. Minimum harvestable ages of 80 to 140 years were used for the Robson Valley Timber Supply Area. For selection management* the first harvest is assumed to occur when forests are 110 years or older.
• Timber utilization — Within cutblocks, all timber which meets or exceeds the following size limits and is suitable for the manufacture of lumber must be utilized:
• 15 centimetre stump diameter for lodgepole pine; 20 centimetres for other species
• 15 centimetre top diameter for cedar; 10 centimetres for all other coniferous species
• Fish and wildlife — Streamside or riparian areas are managed according to the draft Interior Fisheries/Wildlife/Forestry Guidelines. These areas are estimated to cover one per cent of the productive forest land and were not included in the timber harvesting land base.
• Soil conservation — Harvesting and road construction follow regional and provincial guidelines. For the timber supply analysis, it was estimated that 5.7 per cent of the timber harvesting land base will be unproductive for future timber growth, due to roads, trails and landings.
