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UBC Theses and Dissertations

Analysis of some physical and economic criteria for the determination of rotations for British Columbia forests Richmond, A. E.


In I968 the B.C. Forest Service provided growth and yield data in the form of nearly seven hundred volume/age curves. These were summarized quantitatively and sorted by electronic computer. Summaries were used for study of the criteria determining rotations in British Columbia. At the same time an assessment of these curves for other uses in forest land management was made. The curve summaries illustrated the need to consider differences in region,species, or growth type, site class and utilization standards. It was shown that a direct, negative correlation exists between rotation length and site index. This was done using the physical criterion which determines the rotation age at the culmination of mean annual increment in cubic foot volume. Because simple volume over age curves do not provide some important data such as numbers of trees per acre and average stand diameter, the study showed how several rough estimates of these would be derived theoretically. No positive conclusions could be drawn. The exercise did show, though, that the use of actual data describing stand density for fully stocked stands would benefit the forest land manager to a remarkable degree. The next step involved an assessment of the available financial alternatives to physical rotation determination, then compared them with approaches employed by two representative agencies in British Columbia. The possibility of using average stand diameter as a means of approximating the financial rotation was indicated. B.C. Forest Service volume/age curves now are useful as a tool of forest land management. They could be improved by the provision of information to define growth behaviour at full stocking, given various levels of stand density. Another conclusion was that the forest manager using the optimum accounting rate of return (single year) investment criterion and the economist using time preference criteria both have the same objective, namely the most efficient use of capital. This objective is more likely to be achieved by the manager in a series of Intermediate steps. At the same time the economist's time preference may span a single rotation. It was recommended that the B.C. Forest Service continue to develop forecasts of average stand diameter with their yield predictions as a means of introducing the financial implications of a chosen rotation.

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