Service (the value of timber harvested in a year, or so called "cut prices") and from commercial price reports for some regions.
The primary difficulty with this valuation approach is selecting the discount rate (r) to be used. Similar difficulties arise in minerals accounting when the net present value approach is introduced. No valuation method escapes this difficulty, except with strong and unrealistic assumptions about intertemporal price paths. A practical approach is to reestimate the discount rate periodically on the basis of an asset pricing model for timberland. The discount rate is then treated in the same manner as timber prices, with a separate revaluation account to reflect changes in the discount rate.