Download Final_Exam 2006

NRM 340 – Final Exam
Name ___________________
1. Explain one advantage and one disadvantage for each of the following sampling
schemes systematic sampling, simple random sampling, and stratified random
sampling.
2. Match the following terms with the correct definition:
a. carrying capacity
b. evenness
c. habitat
____ is the maximum number of animals of a given population that can be
supported by available resources.
____ is the distribution of individuals among the species present
____ describes the resources and conditions present in an area that produce
species occupancy (including survival and reproduction)
3. If the standard deviation of a sample of 72 tree diameters (dbh) is 8 cm calculate
the standard error of the mean.
4. If the mean diameter in the previous problem was found to be 20 cm what would
be the coefficient of variation?
5. What phrase best describes the meaning of “the standard error of the mean”?
a.
b.
c.
d.
the mean deviation of the measurements
the mean of the means
the standard deviation of the means
the coefficient of determination
6. Compare the variability in tree heights in a 20-year-old natural stand of balsam fir
with those in a 4-year-old plantation, given the following data:
Natural Stand
mean = 40 ft
standard deviation = 4.4 ft
Plantation
= 5.9 ft
standard deviation = 0.649 ft
mean
7. What are the three main components of habitat?
8. The following volume data were computed from 15 1/5-acre line-cruise plots on a
34-acre tract:
Plot
1
2
3
4
5
Volume
(ft3/plot)
500
710
425
900
610
Plot
6
7
8
9
10
Volume
(ft3/plot)
415
310
200
490
600
Plot
11
12
13
14
15
The average volume per plot was calculated as 516 ft3. Calculate:
a. The estimated volume per acre
b. The estimated volume for the entire tract
9. Explain what a 95% confidence interval means.
Volume
(ft3/plot)
470
545
450
605
510
10. Calculate Simpson’s Index for the following data:
Species
1
2
3
Abundance
50
25
10
11. How do you interpret the Simpson’s Index value calculated above?
12. You are given the following information:
Stratum
1
2
3
Acreage
125
190
50
# of 1/10-acre
Plots
35
52
13
Average
Volume
(ft3/plot)
275
312
178
Calculate:
a. an estimate of the overall population mean
b. the standard error of the population (w/o replacement)
c. a 95% confidence interval for the population
d. determine the correct proportional allocation of the samples
Variance
24,000
32,000
18,000
13. True or False? Richness is the number of units (i.e., species, ecosystems, etc.) per
unit area.
14. Eleven 1/20-acre sample plots were measured in a 50-acre tract for cubic foot
volume of pulpwood-size trees. The data are as follows:
Yi (ft3/plot)
Plot
1
2
3
4
5
6
7
8
9
10
11
75
75
68
92
75
44
92
44
75
48
68
Calculate the following:
a. The sample mean.
b. The sample mode.
c. The sample median.
15. You have collected data on weight of moose forage for a willow shrub site and
have found for a sample size of 16 that the mean weight per plot (1/10-acre) is 24
kg with a coefficient of variation of 50%. Calculate the 95% confidence limits:
16. Suppose we have conducted a preliminary inventory of 25 plots to estimate
volume per acre of a timber stand. From that sample we estimated the mean to be
4,400 board feet per acre and a standard deviation of 2,000 board feet per acre.
Determine the sampling intensity needed to be within plus-or-minus 5% of the
mean, with a confidence level of 95%.
17. You are told to develop a stratified random sample and allocate a total of 150
1/10-acre plots. You are given the following information:
h
1
2
3
4
Nh
15
45
110
60
Sh
20
70
35
45
a. Allocate these optimally to reduce variability within strata.
18. A forester wishes to estimate the proportion of surviving seedlings in a young
plantation. The seedlings were planted at regular spacing and the forester
randomly surveyed 50 seedlings, finding 40 of the seedlings to be alive. The total
number of seedlings planted in the plantation was 5,000. Calculate a 95%
confidence interval.
19. What is the difference between a dendrometer and hypsometer?