As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Strathcona 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.
The area of the Strathcona TSA that is considered available for timber harvesting under current management practices is about 236 000 hectares. The total volume of standing timber in the area is about 73 million cubic metres, of which 60 million cubic metres is of merchantable age. The area is dominated by stands of Douglas-fir, western hemlock, western redcedar and Sitka spruce.
The current AAC for the Strathcona TSA is 1 693 745 cubic metres per year before temporary reductions to account for harvesting deferrals in three areas that are currently under study as protected areas. These deferrals, and the temporary reduction of 188 000 cubic metres per year, are not modelled in this analysis. Portions of Quadra Island and Boughey Bay which have been recently added to the TSA and together contribute 28 000 cubic metres per year to the allowable annual cut, are not included in this analysis. Therefore, the current AAC is assumed to be 1 665 745 cubic metres per year from the areas included in this analysis.
Using current forest management assumptions, the analysis results indicate that the current harvest level must be reduced immediately by about 12% or 210 000 cubic metres per year to 1.45 million cubic metres per year in order to avoid major future disruptions in timber supply. To continue to avoid major harvest level disruptions, the harvest forecast declines from this reduced initial harvest level by about 12% per decade over the next 4 decades to a low of about 940 000 cubic metres per year, which is 13% below the steady long-term harvest level. This decline to below the long-term level is unavoidable. In about 110 years, when timber harvesting occurs in predominantly second growth stands, the harvest level increases to the steady long-term harvest level of about 1.1 million cubic metres per year.
The harvest level cannot be maintained at or above the steady long-term harvest level at all times, even if it is immediately reduced to the steady long-term level.
Several important factors effect the timber supply forecast. The most important factor is that the original abundance of mature forest which historically allowed harvest rates well above the long-term level no longer exists. In this situation harvest rates must decline towards the long-term level to avoid serious timber supply short falls in the future.
Also contributing to the decline in timber supply are forest cover requirements for non-timber resources such as wildlife and scenic values. However, it is important to note that even if these forest cover requirements were removed, the harvest forecast will show a decline in the near future because most of the original mature forest has been harvested.
Uncertainty in the data and assumptions used
in the analysis may affect results. The harvest forecast is moderately
increased by relaxing forest cover requirements for visual quality
or by increasing the size of the timber harvesting land base.
Increasing forest cover requirements greatly reduces the short-term
timber supply. For the same amount of change (e.g., plus or minus
10%) to an uncertain assumption or piece of data, decreases in
the harvest forecast were generally larger than positive effects.