Harvest flow. Large timber volumes in older forests often enable a variety of short-term harvesting levels without jeopardising the long-term sustainable timber supply. These alternative harvest flows may have a decline to a long-term level, an even flow or step up to a long- term level or even a decline to a level below the long-term before stepping up to the long- term level. For the IFPA review analysis, I requested several alternative harvest flows to aid in understanding the dynamics of the timber supply. These included non-declining and declining harvest flows. The chief forester in his memo on timber supply analysis methodology suggested selecting, if relevant, a ‘base case’ harvest flow that reflects the harvest flow used in the Timber Supply Review base case. In the recent Kamloops TSA timber supply review, the timber supply analysis base case for conventional harvest showed a harvest flow with only a 5% decline between the short-term and the long-term. Consistent with advice in the chief forester's memo on timber supply analysis methodology, I will use non-declining harvest flows for assessing the timber supply impact of innovative practices. I make this choice because the Kamloops TSA timber supply review base case closely approximates an even-flow forecast. Further, I feel that a comparison of this non-declining harvest flow with the non-declining harvest flow that includes the innovative practices reduces the risks to long-term sustainability because the risk of an over-estimate of a short-term AAC increase, that might result solely from the manipulation of harvest flow in later periods, is reduced. Nevertheless, I recognise that a harvest flow at the TSA-level cannot always be mimicked at a sub-unit level. There may be trade-offs at different time periods between sub-units that enable a greater harvest flow at the TSA-level. For the IFPA area, given that the negotiation of operating areas did not use timber supply analysis methodologies, it would be unlikely that the harvest flow would match exactly the TSA harvest flow. I will discuss this factor further under ‘Impacts on other licensees’.
Harvest flow. The purpose of a timber supply analysis is to show the temporal dynamics of timber supply availability in relation to harvest and other management objectives. In a simulation model, as used in this analysis, the harvest flow (i.e., the harvest over time) is dependent on both the underlying model data set and on choices by the modeller. While a modeller has choice of harvest, the selection of a specific harvest flow in one time period can cause changes in harvest flow in other periods. As modelled, the short-term for the IFPA/expedited base has an initial harvest flow that can be maintained for six decades. The IFPA/expedited base analysis, that includes all of the innovative projects, shows little flexibility in the availability of merchantable stock throughout the planning period. This raises concern that, if the managed stands do not realize the predicted yields in the mid-term, there is the potential of mid-term shortages. This shortage would be a direct result of the increased short-term harvesting. Harvesting more in the short-term also has the potential to push other current management objectives to their limits and could prevent future flexibility to adjust for changes in other management objectives such as Mountain pine beetle epidemics and catastrophic events. District staff indicate that they are not experiencing the level of inflexibility suggested by the model. The model has applied a direct spatial adjacency constraint. Branch and regional timber supply analysts have found that the model, CASH6, used the application of the spatial adjacency rules which tends to be more restrictive than what is found operationally. To understand the dynamics of the timber supply, it is desirable to view alternative harvest flows. However, as the IFPA/expedited analysis was near the highest initial harvest level, NSIFS provided no alternative harvest flows for the IFPA/expedited base. The unprecedented increase in the spread of the Mountain pine beetle infestation is predicted (using the MOF Research Branch model and assuming no intervention), to result in approximately 21 million m3 of dead volume by 2009. To address Mountain pine beetle, both as a management tool to slow beetle spread, and for salvage, will likely result in relaxation of forest cover constraints associated with objectives such as visuals. As such, the Mountain pine beetle sensitivity provides a look at higher initial harvest levels where adjacency constraints have been relaxed. These sensitivi...
Harvest flow. I believe that the timber supply availability is not as constraining as modelled, particularly I am willing to assume greater flexibility or relaxation of other management objectives in light of expected Mountain pine beetle management. Nevertheless, I have chosen to reduce the base AAC increase request by 46 375 cubic metres as a level of caution to account for uncertainty around the modelled limited availability. The IFPA-holders in their analysis could have recognized the potential for concern around the limited availability in the short-term and provided greater information on what is constraining and how realistic is the constraint. Further, while the society has recently provided an updated monitoring plan, I am concerned that the society did not pursue providing and implementing the monitoring plan as per the timeline in the previous determination. I will maintain the requirement for monitoring as a condition. Further, I highly recommend, in future analyses, that the IFPA-holders consider providing greater detail around harvest flow issues.
