Timber appraisals are accomplished by tree counting or cruising. An appraisal should determine the average sawlog, peeler log and pulpwood volumes by species. Tree counting involves measuring every tree to record total volume, while a cruise involves measuring a representative sample of trees to estimate the total timber volume.
A cruise is made on a predetermined number of plots on which every tree is measured and listed by product. The number of plots sampled is determined by timber size and density variation of the tract and the desired accuracy. From this smaller sampling, the total quantity and value of products to be sold can be determined.
The following examples are based on cruising a 130-acre tract. A total of 25 sample areas, each 1/5-acre in size, are used to estimate the total volume in the tract. Note that only 4% of the total acreage is counted which will yield an accurate estimate provided the stand has little variability. Example cruise tally sheets for sawlogs and pulpwood are shown in Table 1 and 2. These field tally sheets record the number of trees within diameter and height categories. The volume is calculated using published volume tables. See the Tools Section for different volume tables. In Table 1 for instance, the cruise revealed 10 trees that were 10" DBH that had only (1) 16' Log, 15 trees that were 10" DBH with 1 ½ logs all the way up to 5 trees that were 26" DBH with 3 logs. Once the sample group has been classified by DBH and Height, volume tables are used to determine the board foot volume. The volumes of sawlogs are recorded in thousands of board feet (MBF) while pulpwood volume is recorded in cords.
| # Logs | 1 | 1.5 | 2 | 2.5 | 3 | 3.5 | 4 | Volume Bd. Ft. * |
|---|---|---|---|---|---|---|---|---|
| DBH | Number of Trees | |||||||
| 10 | 10 | 15 | 395 | |||||
| 12 | 10 | 25 | 1435 | |||||
| 14 | 5 | 50 | 5 | 4345 | ||||
| 16 | 12 | 5 | 5 | 2797 | ||||
| 18 | 10 | 5 | 2975 | |||||
| 20 | 5 | 20 | 5 | 7236 | ||||
| 22 | ||||||||
| 24 | 5 | 5 | 4645 | |||||
| 26 | 5 | 5 | 3095 | |||||
| Total | 26,963 | |||||||
Average board feet per acre = 26,963 bd. ft. / 5 acres = 5,392 bd.
ft.
* Calculated using Doyle Scale and Form Class 78
| HEIGHT | 12 | 16 | 20 | 24 | 28 | 32 | 36 | 40 | 44 | 48 | 52 | 56 | Vol. cu ft * |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| DBH | Number of Trees | ||||||||||||
| 6 | 60 | 21 | 9 | 6 | |||||||||
| 8 | 24 | 9 | 39 | 60 | |||||||||
| 10 | 24 | 21 | 6 | 3 | 3 | 3 | |||||||
| 12 | 6 | 9 | 12 | ||||||||||
| Total | 2,593.20 | ||||||||||||
Total cords = 2,593.2 cu. ft. / 128 cubic feet per cord = 20.3 cords
Cords per acre = 20.3 cords / 5 acres = 4.1 cords/acres
* Values obtained using published U.S. Forest Service volume tables
The total board foot volumes contained from the cruise data are used to calculate an average board foot volume per acre (Table 1). This average value, since it is representative of the entire timber stand tract, is used to estimate the total board feet volume for the entire tract. This is achieved by multiplying this average volume per acre by the total number of acres in the tract of timber. In Table 1, the average volume is 5,392 board feet per acre. Thus, if the total timberland tract is 130 acres, there is approximately 700,000 total board feet (700MBF) of sawlogs logs in the entire tract. You must know the quantity of products you have for sale to maximize your economic gains. For example, if a buyer offers a lump sum for all the sawlog timber on your tract, divide the offered amount by the total number of board feet you have for sale to see how much was offered per thousand board feet. If the current average price for sawlogs is $300 per MBF, and someone offers $100,000 for your 700 MBF, given in the above example, the offer appears low. But, if one didn't know he had 700 MBF to sell, the $100,000 may seem like a lot of money and you might quickly agree to the offer. Current prices available in the TimberQuote Tools section represent average values. Thus, your timber could be worth more or less depending on tree quality and size, tract location, hauling distance to the mill, volume of sale, size of tract, difficulty of terrain, local markets and other factors. Price variation can be as much as $100 per thousand board feet.
Similarly, the cruise data can also be used to estimate the pulpwood cords available. A standard cord is a stack of wood containing 128 cubic feet, nominally 4' wide, 4' high and 8' long, but it can be any dimensions that give 128 cubic feet. The number of cords for the pulpwood trees measured on the sample plots of the timber cruise is recorded in Table 2 using published volume tables that give cubic feet of each tree based on DBH and merchantable tree stem length. The total cubic volumes obtained from the cruise are used to calculate the average per acre of the entire timber tract, and to estimate the total. In Table 2, the average pine pulpwood volume is 4.1 cords per acre. Thus, if the total timberland tract is 130 acres, there is approximately 533 cords of pine pulpwood in the entire tract.
You must know the volume of pulpwood on your tract to have a complete estimate of the total quantity of products you have for sale. For example, we now combine the previous estimate of 700 MBF of sawlogs with the 533 cords of pine pulpwood to get the complete quantity of products available for sale on the example 130 acres of timberland. If the current average price for sawlogs is $300 per thousand board feet and $15 per cord for pine pulpwood, the total value of the timber products for sale is $218,000. Thus, one can now evaluate offers made for this tract of timber or make sound economic decisions regarding the management of this tract of land.
Cruising timber is best handled by experienced foresters, but with practice and the rights tools, the timberland owner can become competent in determining timber volumes.
