EXAM II                                              FR 3218/5218                              Semester II - 2002

 

            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. It is my experience that divine intervention seldom occurs during examinations.

            The number preceding the question number is the point value of that particular question. Unless explicitly stated, any number of multiple-choice options (including zero) may be correct responses to the question statement; circle all correct responses. Total points = 45.

 

(4) 1. You have been given the responsibility of sampling the lake bottom of Lake Mille Lacs (a very large lake, 200 square miles, in central Minnesota) for a contaminant. Interest lies in the mean concentration (milligrams of contaminant per gram lake bottom substrate) for the lake as a whole. Describe characteristics of a sample collection process that would lead you to use a two-stage design for this problem (rather than simple random sampling).

 

 

 

 

 

 

 

 

 

 

 

(4) 2. Interest lies in the mean length of windbreaks (windbreaks vary considerably in length) in Morrison County, MN. Ten-chain sample transects (line segments) are randomly placed throughout the county and the length of intercepted windbreaks measured. If the sample average of these lengths is used to estimate the population mean length, the estimate will likely be too ________ (a. high, b. low). What estimator should be used instead?

 

 

 

 

(4) 3. What variable(s) is (are) common to (appears in) all the volume equation types we studied?

            a. form

            b. species

            c. DBH

            d. height

(4) 4. Briefly describe the steps, from data collection to final equation identification, involved in developing a local volume equation given the equation

            V = 0.134 + 0.0023 D2H

where D=DBH and H=total height, is known to be applicable to the population of interest.

 

 

 

 

 

 

 

 

 

(2) 5. List one advantage of a volume ratio system over a series of individual volume tables for estimating multiple, merchantable tree volumes (we, and your book, identified at least two).

 

 

 

(5) 6. Given the taper equation

 

           

 

with variables as defined in class, find the cubic foot volume from ground line to a 6-inch top diameter for a 12-inch DBH tree that is 60-feet tall.

 

 

 

 

 

 

 

 

 

 

(3) 7. Assuming sampling with replacement, we know required sample size is given by

 

           

 

where C is coefficient of variation and P is desired standard error (as a percent of the true value). If 12, 1/10-acre plots are required to achieve desired precision, what is your best estimate of the number of 1/20-acre plots required?

 

 

 

 

 

 

(3) 8. Choice of a “best” plot size in a common timber inventory is a tradeoff between (one correct answer):

            a. cost of measurement and variability among trees on a plot

            b. cost of measurement and variability among plots

            c. variability among trees on a plot and variability among plots

            d. variability among trees on a plot and distance between plots

 

(2) 9. Why are “fixed-radius plots” actually elliptical in shape when used on sloping terrain? What is the orientation of the major axis of the ellipse with-respect-to slope?

 

 

 

 

 

 

 

 

 


(6) 10. The following 8-inch DBH aspen were tallied on 15, 1/10-acre fixed-radius plots:

 

No. Sticks

3

4

5

No. Trees Tallied

5

7

3

 

Use the attached volume table to compute per acre stand and stock table entries for 8-inch DBH aspen. Be sure to label your answers (which is stand and which is stock).

 

 

 

 

 

 

 

(3) 11. In a given stand of trees, does an 8-inch DBH tree have a greater probability of selection with a 1/20-acre fixed-radius plot or a 20BAF variable-radius plot? A 16-inch DBH tree? (be sure to show your work! – guesses will not receive full credit)

 

 

 

 

 

 

 

(2) 12. For an angle gauge, the gauge width and the distance the gauge is held from the eye determine the horizontal angle generated. The “Cruiser’s Crutch,” illustrated in class, compensated for sloping terrain by tapering the gauge width. An alternative means of compensating would be to adjust the distance the gauge is held from the eye. Such an adjustment would require ____________ (a. shortening, b. lengthening, c. sometimes shortening/sometimes lengthening) the distance over what is used on flat terrain.

 

 

(3) 13. The first day on your new job your boss gives you a sketch map of a tract (see below) and asks that you provide her with an estimate of total cords in the tract by species. She says to do a line-plot cruise with a 5% intensity using 1/20-acre fixed-radius plots. She provides you the company individual tree volume table that reports cords by DBH and total height.  She has an important meeting to attend so can’t talk to you further about her request. She says, “Just go do it!”.

 

How many plots will you take?

 

What spacing between plots on a sample line and between sample lines will you use (multiple correct answers)?

 

 

Sketch on the map (does not need to be to scale) how you would lay out the sample lines.

 

What will you need to record for “in” trees on the plots?

 

How could you incorporate some “randomness” into your cruise?