Midterm Make-up Question for Extra Credit
Due Date: 03 November, 2000, 09:00 am
- You will need to print out the SDMD (Drew and Flewelling 1979. For. Sci. 25: 518-32) and SI curves (Forbes. 1961. Forestry Handbook, Ronald Press) for Douglas-fir to answer this question. They are available at:
< https://www.esf.edu/course/ebevilacqua/for322/midterm/sdmd_df.htm > and
< https://www.esf.edu/course/ebevilacqua/for322/midterm/si_df.htm >, respectively.
A forester has a parcel of land that was recently clear-cut and is in need of planting. Prior to the cut, the stand contained predominately Douglas-fir trees. The forester wants to replant the site with genetically improved Douglas-fir seedlings. Based on the site productivity of the previous stand, and the expected increased growth of the new seedlings, the forester expects that the new stand will have a height development trajectory equivalent to the SI = 120 foot for natural stands (index age=100 years). Based on current levels of technology and wood utilization, it is expected that a newly planted forest will be ready for harvest when the quadratic mean diameter of the trees reaches 15-in.
The forester has three options for planting and stand tending:
- plant at a dense spacing of 7'x7', and apply two stand tending operations, one pre-commercial thinning when the quadratic mean stand diameter is 6-in and one commercial thinning before the final harvest;
- plant at a moderate density of 9'x9' spacing, and conduct only one commercial thinning before the final harvest; or
- plant at a wide spacing of 12'x12', conduct no stand tending operations (i.e., no thinnings), let natural density-dependent mortality take its course, and harvest the stand when the trees reach merchantable size.
Using the information given above:
- plot out the trajectory of each option on the SDMD for Douglas-fir (assume you always thin down to the lower limit of zone of optimum density);
- indicate when (in terms of stand age) you would conduct your thinning operations for options (i) and (ii);
- determine the expected volume of wood that could be obtained from each thinning;
- indicate when you expect the stand to reach a quadratic mean stand diameter of 15-in under each option; and
- determine the expected yield at the time of the final harvest.
1. How long will it take for the stand to reach crown closure under option (iii)?
Submission of work:
2. Which of the three options do you feel is the most appropriate? Explain.
3. What are some of the limitations of using a SDMD in this application?
Submit your responses to parts (b)-(e), and questions 1-3 via email (to firstname.lastname@example.org) by 9:00 am, Friday, November 3, 2000. Your response to part(a) (i.e., including both the SDMD and SI curves) must be submitted to my office (301 Bray) by 4:00 p.m., Friday, November 3, 2000. Be sure to clearly illustrate on both SDMD and SI curves how you obtained your answers to parts (b)-(e).
Last Updated by E.Bevilacqua 11/2/00