About Forest Products Measurement
The Forest Products Measurement Unit is part of the Forest Management Service Center. The Forest Management Service Center is a sub-staff of the USDA Forest Service National Headquarters' Forest Management Staff.
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Cruising is the process of measuring forest stands to determine stand characteristics, such as average tree sizes, volume, and quality. The primary purpose of cruising is to obtain a volume estimation to appraise and prepare timber sales. We provide technical expertise in statistical sampling, measurement protocols, and volume estimation procedures. In addition, we develop and/or maintain cruising software, documents, training, and technical support.
Scaling is the determination of the gross and net volume of logs. The primary purpose of scaling is to determine the volume by product or species that will be charged at a predetermined rate, also known as “scaling for payment”. Conventional scaling entails measuring log diameters and lengths, and applying an approved set of rules to deduct for defects. This process is to determine the gross and net volume of a given number (generally log truck loads) of logs. Every log in every load (1-in-1, or 100%) can be scaled, or any one of a number of approved sampling methods can be used, such as scaling a portion of the loads, 3P scaling, or sample weight scaling. Another method being used more frequently is weight scaling, especially on low value material where there is a single species/product, or where all the products being weighed are close to or of the same value. Scale volume may be expressed in terms of cubic feet, board feet, cords, tons, linear feet, or number of pieces.
The Forest Management Service Center provides expertise in estimating volume from logs and standing trees. Our staff provides regional volume estimators for other programs. To promote consistent volume estimation, we maintain the National Volume Estimator Library (NVEL). The NVEL is a collection of the standing tree volume estimators used by the Forest Service. The Service Center also provides support to validate volume estimators, including the current estimators or new estimators a Region might be considering. We provide training for designing a validation study, collecting the appropriate measurements, and the validation software to analyze the data.
An accurate area determination is needed for several methods of estimating volume. The Forest Products Measurement Unit maintains the Forest Service Handbook, FSH 2409.12, Timber Cruising Handbook. Section 50 - Area Determination, and associated parts of other sections, are being reviewed for revision/modification to eliminate conflicting parts and allow the potential use of emerging technology.