Abstract
Clearcutting is the predominant silviculture system currently practiced throughout the Nelson Forest Region (62.7% of the area harvested), followed by seedtree (20.8%), single tree selection (6.7%), group selection (5.7%), and shelterwood (4.1%).
Recently completed Timber Supply Reviews indicate significant reductions in both short and long term wood supply. Additional reductions are anticipated with the implementation of the Forest Practices Code (FPC) and the Kootenay Boundary Land Use Plan (KBLUP). These initiatives indicate that increased reliance on partial cutting systems will be necessary in order to meet biodiversity, visual quality and green-up management objectives while minimizing the wood flow reductions.
This report identifies "low risk" timber types, as well as general silvicultural and operational guidelines for various partial cutting silviculture systems that are applicable to this region. "Low risk" refers to biological suitability and high probability of regeneration success while minimizing the negative effects of Armillaria or other forest pathogens.
Uneven-aged group selection and even-aged patch clearcut and shelterwood systems are the most promising to meet a wide variety of management objectives. Current and regenerated stand structures can be manipulated to maintain or introduce more disease resistant species throughout the rotation.
Partial cutting growth curves for several common stand types were developed using the PROGNOSIS stand growth model. The effects on mean annual increment (MAI) of varying the time of first partial cutting entry, years to final harvest, residual basal area after partial cutting and two levels of Armillaria were identified.
A methodology for incorporating PROGNOSIS stand level partial cutting growth curves into the FSSIM harvest forecast model was successfully developed and the effects of partial cutting and Armillaria on harvest levels was then examined in Boundary and Cranbrook Forest Districts. The results varied between the two districts. In one District, partial cutting maintained short-term wood supply for a longer period of time, with little impact on the long-term wood supply, by addressing constraints imposed by the Forest Practices Code and the draft Kootenay Boundary Land Plan and providing greater flexibility in selecting stands for harvesting. However, when Armillaria was present, losses to the long run sustained yield increased with partial cutting.
A more balanced mixture of clearcutting and partial cutting silviculture systems is recommended. The choice of system is not limited to one of the classical models, but may include variants that take advantage of current stand conditions to meet management, biological and social objectives. An increase in the amount of area harvested annually in the Nelson Forest Region using low risk partial cutting silviculture systems is recommended.
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Updated April 12, 2007
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