Background: Historically the Applegate RD presale department has relied heavily on the 3P (Probability Proportional to Prediction) cruise method for tree measurement timber sales. 3P cruising is relatively quick and easy to learn and implement though recently some shortcomings have arisen when using this cruise method on timber sales on the Applegate RD.
One is the lack of specific data regarding size breakdown of the trees marked for cutting. Both internally and externally this information has become desirable in terms of the need to know the size and amount of timber that is being marked for cutting. 3P cruising tended to only give the total amount of volume by species or species groupings rather than a breakdown by the count and sizes within those species or species groupings.
Another shortcoming has to do with the efficiency of the marking/cruising crew when using the Husky FS2 field data recorders with the NATCDE cruising program. 3P cruising requires a minimum of three keystrokes for each tree tallied with some trees requiring up to six keystrokes. When in the production marking/cruising mode this can really slow the crew down in order for the tally person entering the data on the Husky FS2 to keep up.
Another type of cruise method - Sample Tree (STR) - has been found to overcome these shortcomings encountered when using the 3P method.
Findings and Applications: The presale department on the Applegate RD has utilized the STR cruise method on a number of timber sales in the past couple of years. In designing the cruises using the sample tree method, sample groups within a species or species grouping are set up based on diameter class groupings.
Recently there has been great interest from the concerned public as to the size and number of the trees that were being marked to be cut on timber sales, in particular those trees over 20". By setting a sample group break at the 20' diameter, the desired information can then be collected at the same time the timber sale is marked and cruised while still meeting cruising standards. A separate tally does not need to be kept nor does the sale have to be revisited to determine those trees that were marked that were 20' and over.
In the same vane, a number of the recent timber sales have had a helicopter component that had included smaller diameter, less economical material. In this case a sample group break at 10' or 12' has been useful for logging system design and appraisals for keeping tally on the less economical portion that is marked for cut in those units.
STR also has proven itself to be easier for timber markers/cruisers to consistently apply when calling out the marked trees to the data recording person. Instead of estimating a dbh to the nearest 2"'class and then determining a KPI value for the tree as in the 3P method, the marker/cruiser only has to remember two or three diameter break points for the sample groups. In the case of the Sturgis timber sale, markers/cruisers only needed to know whether a tree was <12', between 12' and 24', or 25' and greater. Calling out marked trees to the data recording person was much quicker since the dbh only had to be estimated closely when it fell near one of the diameter break points for a sample group. Also it was much easier for those employees from different departments who occasionally help out that normally don't mark/cruise on a regular basis.
By using the STR cruise method, the marking/cruising crew has also been able to be more efficient when actually implementing the cruise in the field using the NATCDE cruise program on the Husky FS2 field data recorders. The STR cruise program requires only one keystroke to record an entry that makes it easier for the data recording person to keep pace with the calls from the markers/cruisers.
Follow-up: Based on the timber sales utilizing the STR cruise method during the past couple of years on the Applegate RD, the presale department plans to continue to design timber cruises utilizing the STR cruise method where feasible to be able to meet cruise design standards while at the same time providing the desired sale information to customers both internally and externally.
Submitted by Bob Schroeter; Applegate RD; 541-899-1812