Exam 2                                                 FR 3218/5218                                 Semester II, 2006

 

If it is not clear what a question is asking, request clarification from the instructor. Misreading a question is not grounds for partial credit. To receive partial credit for the calculation problems, formulas and intermediate calculations must be legibly shown. A good strategy would be to go through and answer/set up as much of each calculation question as you can and then go back to fill in details. Time could be an issue.

 

The number preceding the question number is the point value of that particular question. Total points = 90.

 

 (6) 1. We identified two, general circumstances where one might consider using (or be forced to use) two-stage sampling as an alternative to simple random sampling. List the two circumstances OR list one of the circumstances and provide a natural resources example of how/where it arises.

 

 

 

 

(6) 2. What type of water bodies, existing across a regional area, would it make more sense to select a sample of using the line intercept method: lakes or streams? Why?

 

 

 

 

(8) 3. Estimate the cubic foot volume inside bark in the first 12 feet of a 14-inch DBH, 80-foot tall tree using the attached tables. Be sure to show your work and identify the tables you are using.

 

 

 

 

 

 

(6) 4. Use the taper equation

 

           

 

(where d=stem diameter in inches at height h feet up the tree stem of a tree with DBH D and total height H) to find cubic foot volume from a 0.5-foot stump to a 4-inch top diameter of a tree with DBH=10 and total height=60. (you will receive full credit for setting up the necessary equation; “solve” the equation for extra credit only if you have time)

 

 

 

 

 

 

 

 

 

(8) 5. You tallied 200 trees in a timber cruise (interest lie in volume per acre). You only measured height on 50 of the trees; you have DBH on all 200 trees. The volume equation available estimates tree volume using DBH and height. How will you obtain volume for all 200 trees? Be explicit as to the steps you will take.

 

 

 

 

 

 

 

 

(4) 6. Why isn’t stratification often used in what we defined as “in-place” timber inventories?

 

 

 

(6) 7. When you conduct a standard line-plot timber cruise in a stand using plots, you tally trees and get volume, somehow, for the trees tallied. What values do you use in a statistical variance formula in order to assess cruise reliability?

 

 

 

 

(8) 8. You have been told to conduct a line-plot cruise in a 15-acre stand using 25, 1/15-acre fixed-radius plots.

            i. What will your sampling grid be (distance between lines and distance between plots on a line)? (multiple correct answers so show your work)

 

 

 

 

            ii. What plot radius will you use to determine if trees are “in” (43560 square feet per acre)?

 

 

 

            iii. How would you incorporate some “randomness” into plot location?

 

(10) 9. You tallied the following balsam fir trees in a cruise of 25, 1/20-acre fixed-radius plots:

 

Tree DBH

Number 8-foot sticks

Number of trees tallied

8

2

40

8

4

10

10

3

5

10

5

10

10

6

6

12

5

12

 

Obtain tree volumes in cords from the most appropriate of the attached tables.

 

            i. What is the stand table entry for 8-inch DBH balsam fir?

 

 

 

 

            ii. What is the stock table entry for 8-inch DBH balsam fir?

 

 

 

 

(6) 10. Circle the trees on the diagram below that would be counted (tallied) as two trees based on the “walk through” method of boundary overlap correction for the plot.

 

X
 

X
 

 
 

 
 

 

 

 

 

 

(4) 11. What is the motivation for using variable-radius plots (versus fixed-radius plots), as we defined them, when interest lies in estimating value of a stand of timber?

 

 

 

 

 

(6) 12. What needs to be kept over plot center when tallying trees using variable-radius plots with:

            i. a prism

 

 

            ii. an angle gauge

 

 

(6) 13. If you hold the prism tilted as shown in the diagram below when tallying trees in flat terrain (like Minnesota) will you tally (too few, too many, the right number of – circle one) trees.

 

Tree
 

Prism
 

 

 

(6) 14. A 10-inch DBH tree is found to be 20.2 feet from plot center (horizontal distance plot center to tree center) when tallying a 20BAF variable-radius plot. Should the tree be tallied (counted)? You must show the necessary calculation to receive credit.