Chapter 5 Questions and Answers
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Traditional Questions
5.1 A subject stand of naturally regenerated Douglas-fir is growing on site 140 land. It is currently 50 years old and has 5000 f 3 of growing stock. McArdle's normal yield estimates (table 4.4) are the only models available. Make an estimate of the yield available for harvest at age 80 under the following assumptions:
(a) The growth of the subject stand is proportionate to its stocking relative to the normal stand.
(b) The subject stand can realize all of the normal growth potential of the site.
(c) Understocked stands grow fast enough to increase their stocking by 5 percentage points per decade until they are fully stocked.
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5.2 The equation to predict volume per acre in a stand is
ln V = 4 - (100/S) - (12/A) + 0.9 ln BA
The equation to predict future basal area is
ln BA 2 = (A 1 / A 2) ln BA 1 + 5 (1 - (A 1 / A 2))
Where
V = Volume
S = site index
A 1 = current age
A 2 = future age
BA 1 = current basal area per acre
BA 2 = future basal area per acre
Derive an equation to predict future volume V 2 as a function of S, A 1, A 2, and BA.
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5.3 A natural old-field loblolly pine stand is growing on site 70 land and is currently 35 years old, with a basal area of 130 f 2 per acre. The owner has the stand scheduled for harvest in 15 years. You are using the Brender-Clutter model of equation (5.7) and are asked to estimate the following (Hint: Use equation 5.7 to estimate both current and future volume.)
(a) The expected harvest in 15 years.
(b) The periodic annual increment over the next 15 years.
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5.4 A company just purchased considerable acreage of uneven-aged northern spruce-hemlock timberland. The owners want you to evaluate residual stocking levels of 60, 80, and 100 f 2 of basal area for periodic harvests every 10 years to remove all growth. The expected value of poletimber per cubic foot is $0.20, and the value of sawtimber is $0.90. The yield data of Soloman and Frank (table 5.4) are all that is available. The evaluation is to be in terms of periodic annual stand growth value per acre.
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5.5 Given the following stand table and growth-death model, calculate the number of trees by diameter class after one growth period. The growth-death system is given as
Ingrowth into first DBH class = (50 / 0.01 BAS)
Upgrowth from DBH class D to DBH class D+1 = (10 X D / XAL 0.5)
Mortality of DBH class D = (X D / BAS 0.5)
Where
X D= number of trees in diameter class D at beginning of growth period
BAS = basal area of stand at beginning of growth period
XAL = number of trees in stand at beginning of growth period
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5.6 Stand table projections. Given the following growth rates and stand structure before growth, calculate the stand structure after growth. Use the second table projection method that applies average diameter increments, recognizing dispersion within classes.
DBH class midpoint (4 in. classes) |
Number of trees before growth |
Average class DBH growth during period, in. |
Number of trees after growth |
|---|---|---|---|
| 2 | 20 | 3 | |
| 6 | 12 | 4 | |
| 10 | 6 | 3 | |
| 14 | 2 | 1 | |
| 18 | --- | --- |
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5.7 A proposed per-acre stand basal area growth equation is
BAG = 1.5 + 0.04 BA + 0.001 BA 2 - 0.07 A + 0.0001 A 2 - 0.2 S
Where
BAG = annual basal area growth
A = age, in years
BA = basal area, in square feet per acre
S = site index, in feet
Evaluate this proposed equation in terms of growth response to changes in the variables A, BA, and S to determine whether the variable is presented in a biologically defendable manner. Evaluate over the following ranges:
S = 50-100 (index)
A = 30-80 years
BA = 50-400 f 2
Review the last section of the chapter as a guide to this question.
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5.8 List and discuss the important assumptions and factors you would consider before deciding that a candidate growth model is acceptable for estimating the growth and yield of a subject stand managed under a specific prescription.
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ITM Questions
Questions 5.9 to 5.13 that follow are based on the 6 plot tutorial data set for individual tree models described in tables 5.7, 5.8, and 5.9 and figures 5.11, 5.12, and 5.13.
5.9 Make a map showing the habitat type(s) for the 6-acre parcel in year 30 and year 50 before any harvest.
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5.10 Suppose rare endangered pine grouse is only found where there are 15 or less snags per acre and in medium density pine and pine-oak habitats of size 4 and 5. Make a map that shows when and where, if any, such habitat is available to this curious bird.
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5.11 Estimate the three outcomes and conditions for two other management plans. In plan B all units are assigned to prescription 1. In plan C, all units are assigned to prescriptions 2 or 3. Compare your results with what was obtained in the plan shown in table 5.9. What do these results suggest about sustaining long-term diversity of habitat within a forest unit?
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5.12 Define criteria to decide if the habitat mix is both diverse and sustainable. Use your definitions to propose a management policy that you expect will achieve this sustainable condition. Evaluate implementation of the policy with respect to all three conditions and outcomes to see is the criteria are, in fact, satisfied.
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5.13 The individual tree model tutorial presented in the text uses made-up data. It can be converted to a real database for common local forest types in your area for a much more effective teaching tool. Building such a working example is a good team or class term project. A good map, individual tree inventory plots located on the map, and an ITM simulator applicable to the subject forest and forest types are needed. Programs are needed to read the tree lists produced by the ITM model to generate the yield tables. The rules to classify tree lists into forest or habitat types are needed to consistently generate habitat type outcomes for the yield table. If a habitat suitability index database for many wildlife and or plant species is available and if the whole system is linked together in a GIS database, then species-specific habitat suitability outcomes can be generated in the yield tables. Examples of such data sets and the needed programs are found on the book website. They can be used as is, or adapted to local conditions.
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Habitat Questions
5.14 The arithmetic, or average HSI index has also been used to evaluate habitat quality for species K based on the habitat elements of reproduction (R k ), feeding (F k), and resting cover (C k). It is calculated as (R k + F k + C k)/3. Using the same 1.0, 0.67, 0.33, and 0.0 scale for the habitat elements, describe logically and biologically how this compares to the geometric mean model presented in the text as equation (5.26). Which would you expect to show the most good quality habitat in a large rating area? Why? Use the data in table 5.12 to illustrate your answer.
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5.15 Compare the evaluations of pine marten habitat to that of deer habitat over time, both made with spatial habitat models in the Sierra project in figures 5.17 and 5.18. Which of these species is more of a generalist and able to comfortably exist over a wider range of habitat conditions? What are some other generalist animal species and what are some species that are very specific and demanding in their habitat needs? Can you think of some local species of both plants and animals that fall into these categories?
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5.16 The case of a multispecies evaluation of habitat changes over time due to two different management policies are summarized in figure 5.19 (differences in 2190) and figure 5.20 (changes in habitat between 1990 and 2190). Additionally, for every species there is also available a graph like figure 5.18 that tracks the decade to decade change in habitat over the interval. If you were trying to evaluate the relative wisdom of the two policies from a wildlife point of view, that is the most important information to use? Why? If one or two species were listed as threatened or endangered would this make a difference? Should all species be given equal weight in the decisions? Who should assign the weights? Is selecting the best policy a question capable of scientific or analytical resolution?
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Diversity Questions
5.17 How much diversity is, at a minimum, enough to protect or enrich an ecosystem? Can this be represented adequately by numerical values of a diversity index, amounts of habitat by patch or stand size, habitat fragmentation, or spatial pattern indices for a subject ecosystem? (Is this even an answerable question?)
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5.18 What information would need to be examined to determine if the biological diversity of a management unit is sustainable under a proposed management policy?
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5.19 What information and methods to collect it could be used to determine, through monitoring, if, in fact, desired diversity is being sustained?
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