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OPTIMAL HARVESTING OF FOREST AGE CLASSES: A SURVEY OF SOME RECENT RESULTS

Dynamic optimization problems with vintage or age class structures involve complexities that are not encountered in economic models with fewer state variables. These problems have been faced for centuries in forest harvesting decisions, and the earliest ideas for tackling them date from the early 15th century. However, only recently has the harvesting problem with multiple age classes been specified in a form that is fruitful for economic analysis. This survey discusses some of the main properties of the nonlinear discrete time forestry model, which has proven to be tractable in analytical studies and has been used in empirical policy-oriented research. It is shown that the model's stationary state is represented by a set of cyclic solutions and that the maximum radius of the cycle depends on the period length applied in the model specification. The result suggests that it is essential to note that implications of using continuous or discrete variables in specifying time and age structure in age class models with economic optimization.