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Forest Measurements

Keywords: forest products, tree measures, forestry tools; Grade Level: tenth through twelfth grade; Total Time for Lesson: five standard (40- to 45-minute) class periods; Setting: classroom and mature forest, wooded park, or older tree-lined residential neighborhood

Materials

  • Biltmore sticks (one per two students), available from: Forestry Suppliers, Inc., P.O. Box 8397, Jackson, MS 39202 (approx. $10 each) or yard sticks with "cruising stick" cutouts pasted on them (see activity #l)
  • 3 x 5 index cards
  • 12-inch rulers (or unsharpened pencils or strips of wood approximately the same length) (one per two students)
  • Elmer's paper glue or equivalent.
  • two rolls of 1-inch wide masking tape per class.
  • photocopied material: "Forest Mensuration" brochures and study guides and for activities.
  • are for the teacher.
  • calculators (optional)

Concepts to Be Covered

  • Several techniques exist for measuring timber and logs.
  • Accurate measurements are necessary before the landowner, forester, logging contractor, and buyer can put a monetary value on standing timber.
  • Measurements are taken on both standing timber and logs, and on sawed lumber.
  • The goal is to covert standing timber into the number of board feet of lumber that could be sawed from logs that are cut from the trees of that standing timber.

Goals for the Lesson

  • Students will understand the importance of accurate forestry measurements.
  • Students will be able to make simple estimates and use formal measuring techniques.
  • Students will be familiar with some of the measuring terminology used by a forester, logging contractor, or sawmill operator or employee.
  • Students will be able to relate specific measurement units to the products on which they are used to measure.

Methods

  • Direct Instruction: For presentation of terminology and demonstration of measurement techniques; based on material from "Forest Mensuration" brochure.
  • Hands-on Learning: Making measuring devices and actual measuring of trees.
  • Cooperative Learning: Students will complete activities while working in teams of two.
  • Out-of-Class Practice: study guide questions are to be completed as a homework assignment.

State Standards Addressed: E & E: Renewable and Nonrenewable Resources (4.2)

Topics: dimensions of trees and logs in height, diameter, and circumference; quantitative measurements of trees, logs, pulpwood, firewood, and lumber in board feet, cubic feet or cubic inches, cords, or tons; measuring of trees, logs, and lumber as in scaling or grading and the use of tools such as the Biltmore stick; and, briefly, qualitative assessments such as scaling and grading and veneer categories

Evaluation/Assessment

  1. Study guides from "Forest Mensuration" brochure can be graded.
  2. During measuring activities, make sure that students can use the Biltmore sticks correctly and record the data as required.
  3. Measurement techniques and terms and board feet and cord volumetric equivalents can be assessed on subsequent tests.
  4. Tally charts can be graded.

Outline

  • Day 1. Introduction, discussion from "Forest Mensuration" brochure using overhead slides , and hand out brochures and study guides to students
  • Day 2. Activity #l: Make diameter tapes and "cruising sticks" and explain estimating techniques
  • Day 3. Activity #2: Simple estimates of tree heights and diameter measurements with tapes.
  • Day 4. Activity #3: Use of Biltmore sticks (or "cruising sticks") and diameter tapes to measure heights, number of harvestable logs, and possible board feet within five different tree species
  • Day 5. Finish Activity #3 by completing tally sheets , compare and discuss results, conclude lesson, and collect papers.

Day 1

Introduction

  1. In addition to knowing the species of trees on the landowner's property, the marketable timber must be quantified (how many and how much) before a monetary value can be assessed.
  2. The landowner, the logging contractor, and the timber buyer all need to have an accurate estimate on the stumpage value because each party expects to make money on the impending sale.
  3. If saw logs are involved, the lumber mill operator will also need accurate measurements for calculating the expected yield in sawed lumber.
  4. A forester or landowner cannot calculate growth rates without knowing how much there is at a given time.
  5. Therefore, it is essential for all parties involved to be familiar with measuring terminology and techniques.
  6. Although quality is an equally important variable, it should be covered in depth within a subsequent lesson.

Presentation

  • Use overhead slides from appendix to cover and discuss this lesson.
  • Hand out photocopies of "Forest Mensuration" brochure and the study guide prior the end of this class period.

Day 2: Activity # 1

  1. Wrap up the discussion from day one, if necessary.
  2. Assign students to work in teams of two. (Note: They are to remain in the same teams for the duration of the lesson.)
  3. Make diameter tapes: Use any tape-like, non-stretchable material or use two strips of 1-inch wide masking tape, sticky side pressed to the other sticky side. More than two hands will be needed to do this. Mark every 3.14 inch on the tape. Number the first mark as 1, the second mark as 2, and so forth. A typical 24-inch diameter tree will need 24 marks and the tape will be over 6 feet long. Each 3.14 inch mark on the tape will correspond to 1 inch in diameter. See "The Diameter Tape" attached to this lesson plan.
  4. Make "cruising sticks": If you do not have access to Biltmore sticks, you can make a "cruising stick," which can be used as a substitute. Cut out and glue sections from photocopies onto yardsticks or narrow strips of wood at least 1 inch wide and 26 inches long. See "cruising strip" attached to this lesson plan.
  5. If time remains, demonstrate the use of the Biltmore sticks or the "cruising sticks."

Day 3: Activity #2

  1. Students are to continue working in their assigned teams of two.
  2. You will need to take the teams outside to any location with trees (utility poles may be used).
  3. One student ("student A") is to stand at the base of the tree to be measured. A second student ("student B") is to hold a 12-inch ruler (or an unsharpened pencil or similar strip of wood) in a vertical position. Student B will line up the bottom of the measuring device against the bottom trunk of the tree and start walking backward, away from the tree, until the top of the measuring device lines up with the top of the tree. At that distance, student B will stop and rotate the measuring device to a horizontal position as if the tree had been toppled in a windstorm. Student A is to start walking, at a 90 degree angle, from the base of the tree and is to stop when lining up with the "top" of student B's measuring device. Only student B will know when this occurs. The point on the ground that lines up with the tip of the measuring device represents the top of the tree if it were to topple over. Student A is to mark that spot on the ground and count paces back to the tree. To find the estimated height of the tree, convert paces to feet, and multiply by the number of paces.
  4. Have the teams practice using their diameter tapes on the same tree.
  5. The teams are to write their data on 3 x 5 index cards and give them to the instructor after returning to the classroom.
  6. Some students may need assistance converting inches to feet and need to use calculators when multiplying the number of paces by the number of feet in a pace.

Day 4: Activity #3

  1. Students are to continue working in their assigned teams of two.
  2. You will need to take students to a location where there are at least five different species of trees located closely together that would be suitable for harvesting into saw logs. Minimum size requirements are a 12-inch DBH and containing a least one marketable log 8-foot log (preferably one 16-foot log) measured from the stump (18 inches above the soil).
  3. Teams are to use diameter tapes to measure each of five numbered trees (previously marked with a ribbon and numbered) and record their data on 3 x 5 index cards.
  4. Teams are to use Biltmore sticks (or homemade "cruising sticks") to measure the number of 16-foot marketable logs that can be cut from each of the numbered trees. Next use the measuring sticks to estimate the diameters for each numbered tree. Those using Biltmore sticks can record the estimated board feet from the tree directly from a scale on the stick. Teams are to record all data on their 3 x 5 index cards.
  5. For efficiency reasons, teams should remain at each tree until all measurements have been made and recorded. The following data for each tree should appear on each card: number, species, taped diameter, number of 16-foot logs, diameter from either measuring stick, and number of board feet from Biltmore stick (if available).

Day 5: Continue Activity #3

  1. Teams are to complete their tally sheets using reference sheets from data recorded on 3 x 5 index cards.
  2. Add estimated board feet from International Quarter Rule using taped diameters and the number of 16-foot logs from measured data.
  3. Discuss variations between teams.
  4. Discuss variations of estimated board feet between taped diameters and measured diameters by Biltmore sticks.
  5. Collect answers from "Forest Mensuration" study guides. Collect tally sheets .

Conclusion

  1. Reiterate the importance of accurate measurements for the landowner, forester, contracting logger, log buyer, chipping plant operator, paper mill operator, sawmill operator, and manufacturer of finished products such as furniture.
  2. As with any business, businesses-related to wood products are highly competitive. A single timber sale can make millions for those with accurate information or it can result in bankruptcy for those with faulty information on which to base their decisions.

Modifications

  1. For additional procedures to estimate the height of a tree, consult with someone from the math department.
  2. To save two days, eliminate Activities #1 and #2 and only use Biltmore sticks.
  3. For a more realistic study, add more than one tree from the same species to Activity #3.
  4. If you need to have students bused to a suitable forested area, then add other activities such as identification and make an enjoyable day of it for all.

References

Beattie, M., C. Thompson, and L. Levine (1985). Working with Your Woodland, A Landowner's Guide. Hanover, N.H.: University Press of New England.

Forest Service, U.S. Department of Agriculture (1973). National Forest Log Scaling Handbook. FSH 2409.11. United States Government Printing Office.

The Pennsylvania State University. (1999). Advancing in Forestry, 4H Forest Resources Advance Guide. University Park, Pa.: The Pennsylvania State University.

Hansen, Robert S., and James C. Finley (1996). Trees + Me = Forestry . University Park, Pa.: The Pennsylvania State University.

Author

Allen D. McLaughlin, Eisenhower High School