As part of the provincial Timber Supply Review, the B.C. Forest Service has examined the availability of timber in the Golden 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 various harvest forecasts included in this report only indicate the implications for timber supply of current practices and the associated uncertainty. As such, the forecasts should be used for discussion purposes only; they are not intended to imply any particular AAC recommendations.
The Golden TSA covers a total of 921 000 hectares, of which about 174 600 hectares are considered available for timber harvesting under current management practices. Total volume of timber in the area is about 33 million cubic metres, of which 27.5 million cubic metres is of merchantable age. The area is dominated by spruce, Douglas-fir and lodgepole pine stands. The current AAC for the TSA is 650 000 cubic metres.
Given current management assumptions, the analysis shows the current AAC cannot be maintained without causing a drop in future harvest levels. To avoid this drop, the maximum harvest over the first decade is 605 000 cubic metres per year, 7% below the current AAC. Beginning in the second decade, harvests must decrease 10% per decade until the long-term harvest level of 309 000 cubic metres per year is reached 80 years from now.
Initial harvest levels greater than 605 000 cubic metres per year or rates of decline less than 10% per decade results in harvests falling significantly below the long term level, usually around 80 years from now. Conversely, if slower rates of decline are desired, the initial harvest must drop below 605 000 cubic metres per year.
Many of the data and assumptions used in the analysis are subject to varying degrees of uncertainty. In particular, Golden Forest District staff believe that the volumes for existing older stands may be optimistic. they also suggest that the regenerated yields used in this analysis may be too low. Sensitivity analysis was used to examine how uncertainty about these and other data and assumptions affect the results of the timber supply analysis.
In the short term, harvest levels are most sensitive to decreased yield estimates for existing stands. Short-term harvest levels are also sensitive to a decrease in the area of mature forest available for harvesting, tightening of forest cover requirements for non-timber values such as visual quality and wildlife, increased yield estimates for existing stands and increased minimum harvest ages.
The long-term harvest level is highly sensitive to uncertainty about regenerated stand yields and tightening of forest cover requirements. It is also very sensitive to uncertainty about the area available for harvesting. In general the long-term harvest level is not very sensitive to uncertainty about other data and assumptions.