As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Dawson Creek Timber Supply Area (TSA). The analysis assesses how current forest management practices affect the supply of wood 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 total area of the Dawson Creek TSA is approximately 2 278 000 hectares. About 740 000 hectares of the area are considered available for timber harvesting under current management practices of which 529 000 hectares is composed of coniferous forest and 216 000 hectares is covered by deciduous forest. The estimated volume of timber that is currently old enough to harvest is about 87 million cubic metres in coniferous stands and about 22 million cubic metres in deciduous stands. Spruce and pine are the dominant coniferous tree species and aspen is the main deciduous tree species.
The Dawson Creek TSA has separate AAC levels for coniferous and deciduous stands. The AAC from coniferous stands (excluding designated woodlot areas) is currently 841 323 cubic metres per year. The current AAC from deciduous stands (again excluding designated woodlot areas) is 985 000 cubic metres per year.
The results of this analysis indicate that the coniferous timber supply in the Dawson Creek TSA is capable of supporting a nondeclining harvest level that is 12% higher than the current AAC of 841 323 cubic metres per year. However, this analysis also indicates that the current AAC from deciduous stands cannot be supported, and that the rate of harvest from these stands must be reduced if we are to avoid severe drops below the long-term harvest level of deciduous timber supply.
The projected increase in the coniferous timber supply is due primarily to the inclusion of small pine types that have not been previously considered harvestable. Over the long term, these small pine types contribute about 16% of the total coniferous harvest. Another important factor contributing to the increase in the coniferous timber supply is increased timber volume for regenerated stands. In general, regenerated stands are assumed to produce more timber than the existing stands that they are replacing.
The results of sensitivity analysis indicate that the coniferous base harvest forecast shows almost no sensitivity to changes in forest management assumptions, especially in the short term. As a result of the evenflow harvest policy, the large inventory of older existing coniferous stands would be harvested relatively slowly over the next 150 to 200 years. Maintaining this large inventory over the short term provides a great deal of flexibility for dealing with changes in forest management assumptions. As a result, changes to forest management assumptions that reduce the maximum possible rate of harvest have no effect on the harvest forecast because the evenflow harvest level is already well below the maximum harvest rate.
The immediate and severe decline in the deciduous timber supply occurs in part because the deciduous timber harvesting land base is smaller than indicated in previous deciduous timber supply estimates. However, the most significant factor affecting the deciduous timber supply is that the estimated yield of timber from deciduous stands is now far less than previously estimated.
The deciduous timber supply is severely affected in both the short-
and long-term by uncertainty in either the area of the deciduous
land base or stand volume estimates.