FE Ch 16. This workshop will give you some experience in calculating the nutrient content of a Douglas fir forest using information from Chapter 16.

The forest you are working with is a small woodland in Washington County, OR owned by Lyal and Sandy Purinton (http://www.homestead.com/WashCntyOSWA/treefarmtour.html). Their stand of Douglas fir has an average diameter breast height (DBH) of 33 cm with a stocking of 165 trees per acre. Your job is to estimate how much carbon, hydrogen, oxygen, nitrogen, calcium, potassium, magnesium, and sulfur are tied up in these trees. Refer to the tables in chapter 16 for amounts. If a range of values is given, use the middle of the range for your calculations.

To calculate biomass use the following equations for Douglas fir (from Gholz et al. 1979). * means to multiply. Note that these are exponential equations.

1. Calculate the Doug-fir biomass for one acre by tree part and the total.
2. Calculate the mass of C, H, O, N in the wood using the % given here (assume that the roots are mostly dry wood). Dry Douglas fir wood is 52.3% C, 6.3% H, 40.8% 0, and 0.1% N.
3. Calculate the mass of C, H, O, N in the foliage using the % in the chapter for tree foliage.
4. Using data from the chapter, calculate the amounts of N, P, Ca, K, Mg, and S in all parts of the tree. Assume that small root biomass is about 30% of total root biomass and that small and large branches are about 3% and 13%,respectively of the stem biomass.
5. Summarize your calculations in the table below. Give your answers in kg or grams, be consistent.