Measuring the Forest

Ecology Lab

Forests are a valuable resource, vital to the health of humans and other wildlife. In addition to the many goods forests provide (lumber, foods (e.g. mushrooms, deer, etc.), forests perform many ecosystem services including water and air purification, creation of fertile soil, wildlife habitat, carbon storage, and many others. In today’s lab we will discuss forest thinning and learn ecological techniques to sample a forest for merchantable timber and biodiversity.

Objectives:

  1. To engage the class in a discussion of managing tradeoffs between ecological diversity and health, and utilizing harvested resources such as timber products.
  2. To introduce the idea of sustainable harvesting by thinning to extract timber products.
  3. To increase the understanding of Forest ecosystem services to the health and well-being of humans and wildlife diversity.
  4. Perform and evaluate different techniques used to estimate the amount of lumber in a forest by random sampling.
  5. To evaluate the diversity of living and non-living groups in a mature forest stand.

BACKGROUND

A good example of a forest service is New York City’s water supply system, in which water is used from one of the largest protected wilderness areas in the United States. As a result, New York City is one of only 5 major U.S. cities that only need to chlorinate water to ensure purity (for microbial removal).

Ashokan Reservoir, one of NYC’s clean and natural water sources. Notice the surrounding landscape is forested.

Today, the United States contains about 7.4 million acres of forested land. Forested land is definedby the U.S. Forest Service as: ≥1 acre and≥10 percent occupied by forest trees of any size or formerly having had such tree cover and not currently developed for non-forest use. About 1/3 of forested land is owned by the Federal Government. The remaining ~490 million acres are owned by State or local governments, private citizens, or companies. About 2/3 of the forested land in the U.S. (~490 million acres) are classified as timberland (used for the production of commercial wood products). The eastern U.S. contains 70% of these timberlands.

The conservation of our forests is important due to the economic and social value that forests provide. The U.S. is currently the leading producer (and consumer) of forestry products worldwide. Forestry companies research sustainable forestry techniques in an attempt to utilize practices that will ensure the long-term use of forested land. Moreover, because large forestry companies often own large tracts of land, they are constantly monitoring and researching the wildlife in their forests in an attempt to minimize impacts to wildlife populations and ecosystems. It is important to understand how to sustainably utilize forest goods, which can minimize damageto the forest, allow for recovery and continual production of timber products, and maintain thriving populations of many diverse organisms.

When selling timber, the amount of merchantable timberthat can be produced is estimated from a live forest stand. Merchantable timber is the volume of wood that has commercial value, estimated using the diameter at breast height (DBH, 1.37 meters, 4.5 feet above ground on the uphill side of the tree) and height of the tree. As a result, the tips of trees and branches are not taken into account. The value of a tree varies with the economic market, and depends on the amount of merchantable timber, the tree species (most important in determining value), the soundness of the tree (healthy vs. rotted, diseased), and product class.

Three common product classes are used in the forestry industry:

Pulpwood: Trees ≥6-9” DBH are typically chipped into small pieces, chemically treated, and used as paper products, least value.

Sawtimber: Trees ≥14” DBH are cut into lumber and waste material is used as pulpwood, moderate value that depends on tree species / quality.

Veneer: Trees ≥ 16” DBH are converted into continuous sheets of thin wood for production of plywood and furiniture, high value that depends on tree species / quality.

**The lumber of 5 black walnut (Juglands nigra) trees with DBH <18” can sell as veneer for $5,000+.

Today we will travel to Haw River State Park and sample an area of forested land. We will practice random quadrat sampling to evaluate the amount of merchantable timber in the forest and examine the biodiversity of the forest habitat.

PROCEDURES:

A. First Lab

  1. Travel to the forested site and collect measurement data
  2. Collect pictures & Leaves
  3. Use Biltmore Stick to estimate DBH and merchantable tree height
  4. Measure tree circumference and angle of elevation
  5. Estimate habitat coverage of living and non-living groups

***HOMEWORK*** IDENTIFY THE TREES YOU MEASURED TO GENUS / SPECIES USING PICTURES OF BARK AND LEAVES COLLECTED IN FIELD

B. Second Lab

  1. Organize data in an excel spreadsheet
  2. Statistically compare the volume of board feet (using Doyle’s Rule) when estimated using the Biltmore stick vs. Actual measurements using a t-test.

REFERENCES / FURTHER READING

1995. Climate Change Mitigation Strategies in the Forest and Agriculture Sectors. U.S. Environmental

Protection Agency, Office of Policy, Planning and Evaluation, Climate Change Division, Washington,

D.C., USA.

Gardner, W. and Stanton, W. Woodland Owner Notes. NC State University and A&T State University

Cooperative Extension. North Carolina Cooperative Extension Service.

2009 Watershed Water Quality Annual Report. New York City Department of Environmental Protection.

Updated May 2011.

Tools per pair of students: 1 measuring tape, 1 Biltmore stick, 1 meter stick, 1 protractor with attached string & washer, ≥1 pencil, ≥1 set of each data sheet for recording your measures, >20 flagging flags,

2 plastic bags, Camera or Cell phone with camera,

FIELD WORK

Terminology and Abbreviations:

  • (DBH) Diameter at breast height = 1.37 m above ground on the uphill side of the tree
  • In the English linear measurement system (the one used in America, with inches, feet) I use the following abbreviations:
  • 2 inches = 2” ; 2 feet = 2’

Random Quadrat Sampling for the Class:

0m / 5 / 6 / 15 / 16 / 25
10m / 4 / 7 / 14 / 17 / 24
20m / 3 / 8 / 13 / 18 / 23
30m / 2 / 9 / 12 / 19 / 22
40m / 1 / 10 / 11 / 20 / 21
50m / 40m / 30m / 20m / 10m / 0m

The class will measure a 50x50 m square. A flag will be placed at increments of 10m along two sides to facilitate in identification of quadrats. Each pair of students will randomly be assigned to one 10 x 10m quadrat.

FIRST, record who will be Partner 1, and Partner 2 on your data sheet.

Within each quadrat:

Flag the 4 corners of your quadrat

1)Identify the first tree in your quadrat withDBH >12”. This will be tree 1 on your data sheet.

  1. Gather information to help you identify the species of your tree when we return to the lab.
  2. Take a picture of the tree bark
  3. Are there any leaves on the tree?
  4. If yes, obtain one leaf to bring back to the lab
  5. If no, of the leaves on the ground, identify which type is the most common right under the tree
  6. Obtain one leaf to bring back to the lab
  7. Put the leaf in a bag labeled “Tree 1”

ESTIMATIONS WITH THE BILTMORE STICK

2)EstimateDBH

  1. Partner 1:
  2. Hold the Biltmore stick with the side that reads “TREE SCALE STICK” facing you.
  3. Hold the Biltmore stick level, against the tree at 4.5’ above the ground, on the uphill side of the tree.
  4. Adjust your position so your eye is 25” from the stick.
  5. Estimate the diameter of the tree in inches using the scale at the top of the stick.
  6. Record your estimated diameter.
  7. Partner 2: Repeat DBH measurement for the same tree.
  8. Mark the tree trunk about 2 feet above the ground with a ribbon.
  9. Measure a distance 66’ from the base of the tree, and continue to step 3.

3)Estimate tree height in 16 foot logs

  1. Partner 2: Stand 66’ from the base of the tree
  2. Hold the Biltmore stick with the side that reads “Stand 66 FEET FROM TREE, BLUMB STICK 25 INCHES….etc.” facing you.
  3. Line up the bottom of the stick with the ribbon you placed on the tree trunk.
  4. Adjust your position so your eye is 25” from the stick.
  5. Estimate the height of the tree in 16 foot logs (to the nearest 0.5) until the tree:
  6. Tapers to a diameter below 10”
  7. Contains deformities including bends, rotting, holes, etc.
  8. Major branching.
  9. (We want to measure how long the tree trunk is “straight.”)
  10. Record your estimated tree height.
  11. Partner 1: Repeat height measurement for the same tree.
  12. Stay where you are and continue to next section

USING ACTUAL MEASUREMENTS

4)Measure the angle of elevation

  1. Find a location that is approximately:
  2. Level with the ground at the tree’s base where you can see the point on the tree that you used to measure the height in step 3, e, AND
  3. At least as far away from the tree as your estimate of tree height in step 3 (66’ from tree will work in most cases.

(if you estimated the tree height to be 2.5 16-foot logs, then you must be at least 40’ from the tree for this step. 2.5 * 16’ = 40’)

  1. Partner 1: Using a measuring tape, measure the distance in a straight line to the trunk of the tree to that location.
  2. Partner 2: From the location, measure the angle of elevation to the point in the tree you used to estimate height in step 3, e. Record the angle.
  3. Partner 1: Repeat step 4, c.

5)Measure the tree circumference

  1. Partner 2: Using your measuring tape, measure the circumference of the tree 4.5’ above the ground.
  2. Record your measurement.
  3. Partner 1: Repeat tree circumference measurement for the same tree.

6)Identify the second tree in your quadrat with DBH >12“. This will be tree 2 on your data sheet.

  1. Repeat all steps 1-6 for tree 2

7)Repeat all measurements on trees 3, 4, 5, etc. until every tree in your quadrat with DBH > 12” has been measured.

8) Give your partner a high-five.

Tree 1 / Partner 1's measures / Partner 2's measures / Tree 4 / Partner 1's measures / Partner 2's measures
Species: / Species:
BILTMORE STICK / BILTMORE STICK
2) DBH: / 2) DBH:
3) Height in 16 foot logs: / 3) Height in 16 foot logs:
Board Feet: / Board Feet:
ACTUAL MEASUREMENTS / ACTUAL MEASUREMENTS
4) Circumference: / 4) Circumference:
5b) Distance to location: / 5b) Distance to location:
5d) Angle to point used in 3e / 5d) Angle to point used in 3e
Tree 2 / Partner 1's measures / Partner 2's measures / Tree 5 / Partner 1's measures / Partner 2's measures
Species: / Species:
BILTMORE STICK / BILTMORE STICK
2) DBH: / 2) DBH:
3) Height in 16 foot logs: / 3) Height in 16 foot logs:
Board Feet: / Board Feet:
ACTUAL MEASUREMENTS / ACTUAL MEASUREMENTS
4) Circumference: / 4) Circumference:
5b) Distance to location: / 5b) Distance to location:
5d) Angle to point used in 3e / 5d) Angle to point used in 3e
Tree 3 / Partner 1's measures / Partner 2's measures / Tree 6 / Partner 1's measures / Partner 2's measures
Species: / Species:
BILTMORE STICK / BILTMORE STICK
2) DBH: / 2) DBH:
3) Height in 16 foot logs: / 3) Height in 16 foot logs:
Board Feet: / Board Feet:
ACTUAL MEASUREMENTS / ACTUAL MEASUREMENTS
4) Circumference: / 4) Circumference:
5b) Distance to location: / 5b) Distance to location:
5d) Angle to point used in 3e / 5d) Angle to point used in 3e

HABITAT SAMPLING:

10m / 5 / 6 / 15 / 16 / 25
8m / 4 / 7 / 14 / 17 / 24
6m / 3 / 8 / 13 / 18 / 23
4m / 2 / 9 / 12 / 19 / 22
2m / 1 / 10 / 11 / 20 / 21
0m / 2m / 4m / 6m / 8m / 10m

1)Divide your quadrat evenly into 25 sub-quadrats.

  1. If 10 x 10 m, divide into 2 x 2 m sub-quadrats.

2)Identify the location of your 3 assigned sub-quadrats using the numbered chart above.

3)Flag the corners of the 3 sub-quadrats you will be using.

In each sub-quadrat:

4)Estimate the percent of ground covered by each living and non-living group.

  1. Use your best judgment to estimate the actual percentage of the ground covered by each group.
  2. Use the scale of class cover to assign each group a data integer.
  3. Record these estimates on your sub-quadrat charts.

5)Identify the number of different species in each living group.

  1. Ferns, Forbs, Hardwoods, Vines:
  2. Species will differ in leaf shape, bark pattern, bark color, flower color
  3. Grasses:
  4. Species will differ in blade thickness, shape, color
  5. Fungus, Mosses:
  6. Species will differ in color, shape, height, texture
  7. Softwoods:
  8. Species will differ in needle length, # needles per bunch, needle color, cone shape, bark texture, bark color

6)Record the number of species for living groups on your sub-quadrat charts.

7)Give your Partner a high-five.

CALCULATIONS:

Produce an excel spreadsheet to organize your data which shows:

Biltmore Stick / Actual Measurements
Tree Label / DBH (Inches) / Height (16-foot logs) / Doyles Board Feet / International Board Feet / DBH (Inches) / Height (16-foot logs) / Doyles Board Feet / International Board Feet
example / 14 / 2.5 / 90 / 160 / 16 / 3 / 160 / 250
Tree 2
Tree 3
etc…
  1. Using your Biltmore stick estimates, find the number of board-feet using the Doyle Rule and using the International ¼-Inch Rule.
  2. Convert your measure of circumference to diameter using the formula:

C = πD

  1. C = circumference
  2. D = Diameter
  1. Find the tangent of the angle of elevation.
  2. Measure the height of Partner 1’s and Partner 2’s eye from the ground.
  3. Find the height of the merchantable tree using the formula:

H - (height of Partner 1’s or Partner 2’s eye from the ground) = tan() * d

  1. H = Height of the tree
  2. tan() = The tangent of the angle of elevation
  3. d = the distance you stood from the tree
  1. Round your measured height to the nearest 0.5 16-foot logs.
  2. Find the number of board-feet using the Doyle Rule and using the International ¼-Inch Rule.

STATISTICS:

  1. Using the class data, test whether the volume of board feet (Using Doyle’s Rule) differed when estimated using the Biltmore stick vs. Actual measurements using a t-test.

QUESTIONS: (Answer in complete sentences for full credit)

  1. How have forests contributed to your health and well-being?
  1. Propose a hypothesis regarding the accuracy of DBH measured with the Biltmore stick vs. Actual measurements.
  1. Propose a hypothesis regarding the accuracy of tree height measured with the Biltmore stick vs. Actual measurements.
  1. Do the results of a t-test support or refute your hypothesis? (include t-statistics, d.f, and p-value)
  1. How many board feet of each tree species do you estimate will be harvestable in 2,500 m2 of forest using the Doyle Rule?
  1. Should people who own forested land be allowed to harvest their own land freely or should their ability to harvest this land be regulated by government officials?
  1. Does your knowledge about the ecosystem services that forests provide influence your answer to question 6? Why or why not?
  1. What group(s) predominantly covered the forest floor?
  1. Was the most common group you sampled in your quadrat represented by the greatest number of species?
  1. Produce a graph that illustrates the percent coverage of the forest floor using the scale class of cover estimates.
  1. Attach the excel spreadsheet of your organized data as listed under CALCULATIONS.