Notes on Forestry and Wood-Use

Purdue University	Mimeo F-49
Cooperative Extension Service	December, 1964
Lafayette, Indiana
CRUISING FOR PULPWOOD BY THE TON WITHOUT CONCERN FOR TREE DIAMETER: POINT SAMPLING WITH DIAMETER OBVIATION
Thomas W. Beers, Department of Forestry and Conservation
Introduction
In general, the modern field forester is aware of and applies point sampling in routine inventory work. He should, however, be alert for refinements and new approaches which can make his work more efficient and/or more usable. The technique discussed here is an example of such a refinement, for by slight modification of the basic tree volume formula (or table) the time-consuming chore of measuring (or even estimating) tree diameter can be completely avoided with no loss in the accuracy of the results.
The practice of scaling and cruising of timber by weight has been picking up momentum in recent years since in many cases it has been found more efficient than the usual volumetric system in terms of cubic feet or cords . Concurrently, point sampling has been developing, and many refined approaches were proposed, one of which enabled the cruiser to classify trees into broad diameter groups (ocularly) and thereby speed up the field work with some sacrifice in the accuracy of the results. It was not, however, until the published observation by Miller (1963) that the refinement of completely ignoring tree diameter with no loss in accuracy was made clear.
By combining this refinement with the desire to cruise directly in terms of tons, a
powerful field technique is available. The purpose of this paper is to describe the method in sufficient detail so that modifications using refined constants suitable for local conditions can be made. The tally form and constants used in the example should be satisfactory for most Indiana hardwood forests.
A complete example utilizing a tally format found to be suitable at Purdue is shown in Figure 1. In the field the forester visits a pre-determined number of sample points and makes a dot tally by species (if desired) and merchantable height in terms of number of sections of the appropriate length. Only those trees are tallied which "qualify" when scrutinized with a wedge prism or other suitable angle gauge. The only other item needed from the field is the number of points visited, the tally of which is facilitated by the column of numbers along the left edge of the form.
Work-up of the Field Tally
The procedures necessary for the completion of the form are summarized below. All calculations can be made on the form using a desk calculator, slide rule, or as a last resort "mental magic."
1.	Enter basal area factor and expansion constant obtained from Table 1 or by