As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Quesnel Timber Supply Area (TSA). The analysis assesses how current forest management practices affect the supply of wood available for harvesting over the next 250 years. 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 harvest forecasts in this 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. This report does not include an analysis of the potential timber supply impacts of the CaribooChilcotin Land Use Plan, or timber harvesting requirements under pulpwood agreements in the Quesnel TSA.
The total area of the Quesnel TSA is approximately 1.65 million hectares. The area of the TSA that is considered available for timber harvesting under current management practices is approximately one million hectares. The total volume of standing timber in this area is currently about 180 million cubic metres, of which 160 million cubic metres are of harvestable age. The area available for timber harvesting is dominated by stands of lodgepole pine, with some spruce and Douglasfir.
The current coniferous AAC for the Quesnel TSA (excluding the volume allocated to woodlot licences) is 2 265 500 cubic metres per year. The coniferous AAC is partitioned into two components: 1 965 500 cubic metres per year from traditional forest licence areas, and 300 000 cubic metres per year from highdensity stands of lodgepole pine and other problem forest types. The Quesnel TSA also has a deciduous AAC of 50 000 cubic metres per year, but because no deciduous harvesting licences have been issued to date, the deciduous timber supply is not analysed in this report.
Using current forest management assumptions and timber volume estimates, the analysis results indicate that the current harvest level may be maintained for 70 years. To avoid major future shortfalls, the harvest level must then be reduced over a 20year period to the longterm harvest level of 1 955 500 cubic metres per year, 14% below the current harvest level.
This analysis shows that the initial harvest level can be increased to 2.9 million cubic metres per year without causing future shortages in timber supply. However, this harvest level can only be maintained for 2 decades before declining by 10% per decade to reach the longterm harvest level 50 years from now. To attain this initial increase, harvest levels 40 to 80 years from now would be significantly lower than in the base case.
Several important assumptions affect the supply of timber over time. The most important factor is the contribution of problem forest types to the timber supply. Problem forest types have been harvested for the past 3 years. The analysis assumes that harvesting in these highdensity pine stands will continue at an increasing rate. This analysis also assumes that 70 000 hectares of land not considered to be satisfactorily restocked with trees will be rehabilitated to productive forest over the next decade, and that no more of these areas will be created. Furthermore, the analysis assumes that skid trails, fireguards and landings will be reforested, without a loss in growing site productivity. Each of these assumptions influences the harvest forecast, and changes in these assumptions could affect how long the current harvest level can be maintained.
Uncertainty in the data and assumptions used in the analysis
may affect results. The results of the sensitivity analyses indicate
that a more restrictive, 5pass harvest system may be
adopted in the Quesnel TSA without requiring a reduction
in harvest levels. A 10% reduction in the area available for
timber harvesting would permit the current harvest level to be
maintained for 4 decades, although the longterm harvest
level would be reduced. Increases in mature forest cover requirements
and greenup requirements would have an impact on the longterm
harvest level, but would not have an impact on harvest levels
for the first 3 decades. Eliminating forest cover requirements
would permit the current harvest level to be maintained for 10 decades.
The harvest forecast is also sensitive to uncertainty in the
estimates of existing stand volumes. If existing stand volumes
are 20% greater than has been estimated, the current AAC may be
maintained for up to 20 decades. However, if existing stand
volumes are 20% less than has been estimated, an immediate 35%
reduction in the harvest level would be necessary to avoid timber
supply shortages in the future.