Exam 2                                                   FR 3218/5218                                    Semester II, 2005

 

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.

 

You can choose one (1) 4-point value question not to answer (cross that question out).

 

The number preceding each question is the point value of that particular question. Total points = 49.

 

(4) 1. For the same total number of sample units, simple random sampling will almost always result in a lower standard error, i.e. higher precision, than two-stage sampling (n in simple random sampling equal to n*m in two-stage sampling). So why is two-stage sampling ever used? There are two reasons/types of circumstances.

            i.

 

 

            ii.

 

 

 

(4) 2. Line intercept sampling is to be used to estimate the number of downed (laying on the ground) trees in an old-growth forest. What, if anything, needs to be measured on “intercepted trees” (trees that a sample transect intercepts) to compute the estimate of number of downed trees?

 

 

 

(4) 3. We identified four types of volume tables (equations): form class, standard, composite, and local. How does a composite volume table differ from a standard volume table?

 

 

 

 

(4) 4. You are interested in inside bark cubic foot volume below a 5-inch top diameter for a 12-inch DBH, 60-foot tall tree. You estimate the 5-inch top occurs at 45 feet up the tree bole. Use the attached table(s) to estimate the volume you are interested in. Identify which table(s) you use.

 

 

 

 

 

(4) 5. For question 2. on the homework assignment you just completed you evaluated using

           

as the basis for a local volume equation. Which was preferred? Why?

 

 

 

(5) 6. You are going to use a line-plot cruise, with random starts, in a square grid pattern for a 25-acre stand. You will take 10 plots total. (be sure to indicate units with your answers)

a.       How far from the tract edge should you place the first line?

 

 

b.       How far apart should the remaining lines be?

 

 

c.       How will you place the first plot on each line? Be specific.

 

 

d.       How far apart should the remaining plots on a line be?

 

 

e.       You complete cruise as outlined and end up taking only 8 plots. What do you do? Be specific.

 

 

 

(4) 7. What is the radius (in feet) of a 1/20-acre circular plot?

 

 

 

(8) 8. The following trees (8 total) were tallied on a 1/20-acre fixed-radius plot:

 

Number of trees tallied

Tree DBH (in.)

Individual tree volume (cords)

3

8

.07

1

8

.08

4

10

.12

 

Compute the following observations (specify units):

a.       trees per acre

 

 

b.       basal area per acre

 

 

 

c.       volume per acre

 

 

 

(4) 9. Eighteen (18), 8-inch DBH aspen were tallied on 25, 1/15-acre fixed-radius plots. Compute the stand and stock table entries for 8-inch DBH aspen or tell me why you cannot compute an entry.

 

 

 

 

(4) 10. Why are variable-radius plots used more commonly than fixed-radius plots when interest lies in the timber value of a forest tract?

 

 

(4) 11. How far can a 10.5-inch DBH tree be from a sample location and still be “in” on a 15BAF variable-radius plot? What distance should you measure (BE SPECIFIC) to compare the computed value to?

 

 

 

 

 

(4) 12. You are using the walk-through method of boundary overlap correction with variable-radius plots. Refer to the schematic diagram below. Trees X and Y have been determined to be “in” for the sample location. Which, if either, tree(s) should be double counted due to boundary overlap?

 

X