As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Prince George Timber Supply Area (TSA). The analysis assesses how current forest management practices affect the supply of wood available for harvesting over both the short (next 20 years) and the long (next 250 years) term. It also examines the potential changes in timber supply stemming from uncertainties about forest growth and management actions. It is important to note that the various harvest forecasts included in the report indicate only the timber supply implications of current practices and uncertainty. As such, the forecasts should be used for discussion purposes only; they are not allowable annual cut (AAC) recommendations.
The Prince George TSA consists of about 7 510 000 hectares of land located in the central interior of British Columbia. About 3 620 000 hectares of the area are considered available for timber harvesting under current management practices. The area is dominated by forests of hybrid Engleman-white spruce, lodgepole pine, and subalpine fir with minor amounts of Douglas-fir, cedar, trembling aspen, and hemlock.
The results of this analysis indicate that using current inventory and timber growth information, and assuming continuation of current forest management practices, the current AAC for the TSA of 9 073 661 cubic metres per year can be maintained. (This AAC and analysis do not address allowable harvests from woodlots.) The analysis indicates that it is possible to harvest at a rate of 9 630 000 cubic metres per year 6% higher than the current AAC without declining for 250 years. Alternative harvest forecasts indicate that the initial harvest level can be increased without affecting the long-term harvest level.
This analysis reflects current knowledge and information on forest inventory and growth. However, it is important to recognize that uncertainty exists about several of the factors that define timber supply. A series of sensitivity analyses indicate that these uncertainties can affect timber supply to varying degrees. Three important factors which may affect future harvest levels are uncertainty about the size of timber harvesting landbase, and uncertainty about estimates of timber volume in existing and future stands.
Uncertainty in the size of the timber harvesting land base is particularly important because the projected increase in timber supply, relative to the current AAC, is due primarily to the increased inclusion of marginally economic stands that were previously considered non-merchantable. The timber supply analysis does not account for possible future changes in the land base due to the Protected Areas Strategy, Forest Practices Code, Land and Resource Management Plans, Native land claims and Local Resource Use Plans.
Another important factor contributing to the projected increase in timber supply is the use of managed stand yield estimates to project the volume of regenerated stands. In general, the managed stand yield estimates are about 20% more productive than the existing stands they will replace.
The results of sensitivity analysis indicate
that the harvest forecast shown in the base case is generally
unaffected by changes to forest management assumptions, especially
in the short term. This is due primarily to the abundance of
existing mature timber that allows flexibility in the schedule
of harvests.