Midterm Make-up Question for Extra Credit

Due Date: 03 November, 2000, 09:00 am

  1. 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:
    1. 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;
    2. plant at a moderate density of 9'x9' spacing, and conduct only one commercial thinning before the final harvest; or
    3. 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:

  1. 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);
  2. indicate when (in terms of stand age) you would conduct your thinning operations for options (i) and (ii);
  3. determine the expected volume of wood that could be obtained from each thinning;
  4. indicate when you expect the stand to reach a quadratic mean stand diameter of 15-in under each option; and
  5. 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)?
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?

Submission of work:
Submit your responses to parts (b)-(e), and questions 1-3 via email (to ebevilacqua@esf.edu) 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