In forestry management it is important to know the net stumpage value of a stand (that is, a group) of trees. This is the commercial value of the trees minus the costs of felling, hauling, etc. The graph in the figure shows the net stumpage value V, in dollars per acre, of a Douglas fir stand in the Pacific Northwest as a function of the age t, in years, of the stand.†
(a) Estimate the net stumpage value of a Douglas fir stand that is 100 years old.
(b) Estimate the age of a Douglas fir stand whose net stumpage value is $20,000 per acre. yr