but measures only the logs indicated by the sampling rate. All 

 personal bias in choosing the log to be measured must be eliminated 

 by strict rules of selectiono Accuracies of 2^ percent or better 

 can be obtained, which compares favorably with accuracies of complete 

 log scaling based on check scales. The advantages lie solely in 

 the reduced cost of scaling. If the time saved by a scaler in sample 

 scaling cannot be profitably used elsewhere, he might just as well 

 scale every log. Sample scaling is not being used much at the present 

 time because large collections of logs are usually not available. 

 Commonly, a scaler is kept busy by scaling only a few logs at several 

 different sales, or he is r'equired to stay on duty at one mill or 

 landing v/here logs are not coming in at a rate that would make sampling 

 advantageous. The present high stumpage values and the variety of 

 species and prices in the same sale have also discouraged the use of 

 sampling . 



TREE MEASUREMENT 



The high cost of log scaling and the large work load it creates on 

 ranger districts vjhere numerous sales are simultaneously in progress 

 have led to the use of tree measurement in many Forest Service sales, 

 With partial cutting and generally better silviculture being stressed 

 in national forest timber m.anagement, marking every tree to be cut on 

 timber sales is essential. The opportunity is therefore at hand for 

 m.easuring the board-foot contents of the trees at the same time. The 

 tree measurement process consists of measuring the dob oh, and estimat- 

 ing the height. The volume for each tree is read from a volume table 

 for the species concerned and recorded in a scale book. Numbering, as 

 well as marking, each tree either with a blaze or a paint gun both 

 above and below the point of cut is required,, A certain percentage of 

 the trees must be check scaled by measuring the logs after the trees 

 have been felled and bucked in order to adjust the volumes determined 

 by the tree measuring process, A ratio of scaled volume to tree 

 measured volume for the same trees gives a correction factor to apply 

 to the total tree measured volume. Errors in measurement, errors due 

 to defect and breakage, and discrepancies in volume tables are found 

 and adjusted by the check scale. Throughout this report, the term 

 check scale will refer to the above-described process and not to the 

 conventional process of re-scaling a number of logs to check the 

 original scale. 



Tree measurement has several advantages over log scaling. The timber 

 can be marked and measured in one operation. Often better utilization 

 can be obtained because the purchaser pays for every tree that is 

 marked and must, therefore, remove all marked trees or suffer a loss. 

 The necessity of a check scale requires the forest officer to visit 

 the sale area frequently. Frequent visits to the sale area should 

 result in better inspection and supervision. Tree measurement elimi- 

 nates the need for cruising of sale areas. Units ready to be logged 



