| Abstract
| - This paper propounds a new method of calculating numerical thinning schedules for conifers which are designed to give, on the average, any reasonable pattern of ring width at breast height in the 100 largest trees in a plantation. It starts from the Forestry Commission's Revised yield Tables for Conifers in Great Britain and is based on the principle that, if the current annual increment in a plantation is unaffected by the grade of thinning, the ring widths must be inversely proportional to the bole area per acre, i.e. the total area of cambium on the main stems of the trees. Sources of error in the method of calculation are discussed, and it is considered that such errors are not so serious as to endanger the use of the method as a means of calculating approximate thinning schedules. As an approximate yield table can be constructed for each thinning grade, the method can be used to estimate the relative costs of growing trees of various diameters with various ring width patterns.
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