As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Fort St. John 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 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 total area of the Fort St. John TSA is 4 673 000 hectares. About 1 194 000 hectares of the area are considered available for timber harvesting under current management practices, of which 769 733 hectares are composed of coniferous forest and 424 391 hectares are covered by deciduous forest. The estimated volume of timber that is currently old enough to harvest is about 110.20 million cubic metres in coniferous stands and approximately 40.50 million cubic metres in deciduous stands.
Pine and spruce are the dominant coniferous tree species and aspen is the main deciduous tree species.
The Fort St. John TSA has separate AAC levels for coniferous and deciduous stands. The AAC for coniferous stands is currently 900 162 cubic metres per year. The current AAC for deciduous stands is 915 000 cubic metres per year.
The results of this timber supply analysis suggest that the coniferous timber supply in the Fort St. John TSA is capable of supporting a nondeclining harvest level of 1.76 million cubic metres per year (95% higher than the current AAC of 900 162 cubic metres per year). This analysis also indicates that the current AAC from deciduous stands can be maintained for 20 years and that the rate of harvest must be reduced after that time to avoid severe drops below the longterm deciduous timber supply level.
The projected increase in the coniferous timber supply relative to the current AAC is due primarily to the inclusion of areas previously not contributing to the timber supply. Pine stands constitute 56% of the coniferous timber harvesting land base. Another important factor contributing to the increase of the coniferous timber supply is increased estimates of timber volumes from regenerated stands. In general, regenerated managed stands are expected to produce more timber at harvest than the existing stands that they are replacing.
The above results reflect 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 indicates that these uncertainties can affect timber supply to varying degrees.
The results of sensitivity analysis indicate that the coniferous base case harvest forecast shows almost no sensitivity to uncertainty in forest management assumptions or information, especially in the short term. This is largely a result of the nondeclining harvesting pattern used in the base case. This base case harvest pattern results in an abundance of mature volume available in the shortterm which can absorb many of the changes tested in the sensitivity analysis.
The forecasted decline in the deciduous timber supply, relative to the current AAC, 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 timber yields from deciduous stands are lower than previously estimated.
The deciduous timber supply is highly affected, in the medium
and longterm, by uncertainty in either the deciduous timber
harvesting land base or deciduous stand volumes.