As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the 100 Mile House Timber Supply Area (TSA). The analysis assesses how current forest management practices affect the supply of wood available for harvesting over the both the short (next 30 years) and long (next 200 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 100 Mile House TSA covers a total area of approximately 1.22 million hectares, of which about 0.74 million hectares are considered available for timber harvesting under current management practices. The total volume of standing timber in the area is about 115 million cubic metres, of which 72 million cubic metres is of merchantable age. The area is dominated by stands of lodgepole pine, Douglasfir, and spruce.
The current AAC for the 100 Mile House TSA is 1 250 000 cubic metres per year, of which 13 000 cubic metres is allocated to woodlot licences. However, the volume allocated to woodlots is not considered in this analysis, and therefore the current AAC is assumed to be 1 237 000 cubic metres per year in this analysis.
Under current forest management assumptions, the analysis results indicate that the current harvest level of 1 237 000 cubic metres per year can be maintained throughout the 200year planning horizon. At some point beyond that 200year horizon, the harvest level can increase to the longterm harvest level of 1 250 000 cubic metres per year. Increasing to the longterm harvest level earlier will result in harvest shortfalls in the short or longterm.
The current harvest level can be maintained for 200 years in part because 60% of the timber harvesting land base is currently old enough to harvest. There is enough mature timber to maintain the current harvest level; however, the longterm harvest level cannot be achieved until the mature stands have been replaced by highly productive regenerated stands.
There are several factors affecting the length of time it takes to reach the longterm harvest level for the 100 Mile House TSA. First, the current harvest level is only 1% below the longterm harvest level. Furthermore, the average volume per hectare harvested is projected to be 13% less in the long term than in the short term. As a result, it takes a long period of time to accumulate enough volume to increase to the longterm level. For these reasons, it is not until beyond the 200year planning horizon that the harvest level is projected to increase by 13 000 cubic metres per year to the longterm harvest level.
Uncertainty in the data and assumptions used in the analysis may affect results in the following ways. The supply of timber, both the short and longterm, may be moderately increased if less area is required to meet oldgrowth requirements or if the size of the timber harvesting land base is increased. Similarly, requiring more area to meet oldgrowth requirements, or decreasing the size of the timber harvesting land base may moderately decrease the timber supply. Uncertainty in existing stand yields may have a small impact on the shortterm harvest level, but it has no impact on the longterm harvest level. Uncertainty in regenerated stand yields has no impact on the shortterm harvest forecast, although there may be a moderate to high impact on the longterm harvest forecast. All the other ranges of uncertainty considered in the analysis have either a low impact or no impact at all on both the short and longterm harvest forecasts.