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UBC Theses and Dissertations

The influence of cut-block size and adjacency rules on harvest levels and road networks Finn, Steven Terence


Previous harvesting practices in coastal British Columbia generally favoured large opening sizes with relatively short regeneration periods before adjacent blocks were removed. These large openings were both criticized for being aesthetically unpleasing and for not providing a proper age class distribution for wildlife habitat. To combat these problems, smaller opening sizes with longer times between harvesting of adjacent blocks have been proposed. It is believed that smaller opening sizes and more rigid adjacency constraints will impact cutting levels and harvesting and transportation costs. An area-based scheduling model was developed between 1989 and 1991 which quantifies these impacts and provides a better understanding of the harvest levels and costs associated with different cut block sizes and adjacency constraints. The effect on the Annual Allowable Cut (AAC) due to block size and exclusion period showed that the delay period had a greater effect on the AAC than did block size. As the block size decreased while keeping the delay period constant, the reduction in AAC ranged from 6.0% to 23.5%. As the delay or exclusion period increased, adjacency constraints limited the number of blocks available for harvest and therefore reduced the harvest volume. Increasing the delay period from I to 2 and from I to 3 caused volumes to drop an average of 18.6% and 40% respectively. Increasing the delay period and decreasing the block size resulted in large reductions in harvest volume of up to 50%. Another effect of increasing the delay period and decreasing the block size is that a large number of blocks may never be harvested. Values ranged from 6.8% to 43.8% of blocks not eligible for harvesting. A stumpage calculation showed that there is a drastic difference in the amount of stumpage payable when comparing the different sized blocks and adjacency requirements. Values ranged from $119.7 million to $52.8 million, a reduction of nearly $67 million as the block size was decreased and the adjacency requirements increased.

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