As in the case of the fishery, the analysis of the values of alternative uses of the forest is
based on a bioeconomic model. The biological component of the model describes the growth
of the volume of timber over time on a hectare of forest land. The economic component of
the model places dollar values on the output of forested land under alternative patterns of use.
These values are obtained by subtracting the cost of a particular use from the market value of
the good or service produced. As noted above, some uses, such as recreation, occur more or
less continuously, whereas logging occurs intermittently. The values of alternative uses of the
forest can be assessed by comparing the present values of alternative flows of goods and
services - the site value under alternative uses - or by converting site values to constant
annual rental values for comparison.