Using a spreadsheet program, calculate the volume of timber each year after planting for a period of up to 130 years for a single unfelled stand of timber for which the age–volume relationship is given by S = 50t + 2t 2 − 0.02t 3

(where S and t are defined as in the text of this chapter). Is it meaningful to use this equation to generate stock figures up to this stand age?

Also calculate:

(a) The year after planting at which the amount of biological growth, G(S), is maximised.

(b) The present-value-maximising age for clear felling (assuming the stand is not to be replanted) for the costs and prices used in Table 18.4 and a discount rate of 5%.

(We suggest that you attempt to construct your own spreadsheet program to answer this question. If you find that this is not possible, you can obtain the answers by adapting Sheet 4 in Chapter18.xls.)