As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Queen Charlotte 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 Queen Charlotte TSA covers a total area of about 465 000 hectares, of which about 61 000 hectares are considered available for timber harvesting under current management practices. The area is dominated by stands of older-aged western hemlock, western redcedar and Sitka spruce. The current AAC for the Queen Charlotte TSA is 514 335 cubic metres per year, apportioned to a mixture of temporary and replaceable licences.
Using current forest management assumptions, the analysis results indicate that the current harvest level must be reduced immediately by about 14% or 72 000 cubic metres per year to 442 000 cubic metres per year in order to avoid significant future shortfalls in timber supply. To continue to avoid major harvest shortfalls, the harvest forecast declines from this reduced initial harvest level by about 12% per decade over the next 6 decades to a low of about 205 000 cubic metres per year, which is 17% below the steady long-term harvest level. In about 150-180 years, when timber harvesting is projected to occur in predominantly second-growth stands, the harvest level increases to the steady long-term harvest level of about 248 000 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 factors contribute to the decline in the timber supply forecast. The most important factor is that the base harvest forecast is well above the steady, long-term harvest level. In this situation harvest rates must decline towards the long-term level to avoid serious timber supply shortfalls in the future. Also contributing to the decline in timber supply, to some extent, are forest cover requirements for forest resources such as biodiversity and scenic values. However, it is important to note that even if these forest cover requirements are removed, the harvest forecast still shows a decline in the near future. An additional contributing factor is that existing forests are dominated by older stands on poor growing sites yielding lower than average volumes of timber.
Uncertainty in the data and assumptions used in the analysis may
affect results. For example, the projected harvest forecast is
increased slightly by relaxing forest cover requirements for visual
quality and biodiversity. In general, changes in the expected
yields of existing and regenerated stands as well as changes in
the size of the timber harvesting land base has the greatest effect
on both short- and long-term timber supply projections.