A special cascading fixed charge structure can be used to characterize a |orest management ptanning problem in which the objectives are to identify the optimal shape of forest harvest cutting units and simultaneously to assign facilities for logging those units. We describe a four-part methodology that has been developed to assist forest managers in analyzing areas proposed for harvesting. This methodology performs an analysis of harvesting feasibility, computes the optimal solution to the cascading fixed charge problem, undertakes a GASP IV simulation to provide additional information about the proposed harvesting operation, and permits the forest manager to perform a time-cost analysis that may lead to a more realistic, and thus improved, solution.Designing optimal forest harvest cutting areas, or units, and assigning logging equipment to them are two of the more difficult problems faced by those involved in commercial forest management. During the 1930s, forest managers became interested in the problem of defining the optimal shape of forest harvest cutting units. Matthews (1942) intuitively derived the optimal cutting unit shapes for two forest management situations. The first was an isolated cutting unit, that is, a unit without boundary interaction with adjacent units. For this case, Matthews argued that the optimal shape was circular, assuming that the timber on the area was uniformly distributed and that logging costs were composed of a fixed component plus a variable component that was linearly related to the distance from the tree to the central landing (where the logs are assembled to be loaded onto trucks). The second situation involved the same assumptions as the first, but allowed for interaction with adjacent units. For this case, Matthews thought that the optimal shape was a rectangle.Analytical work by Lussier (1961) and Peters (1978) has shown that, for the assumptions listed above, Matthews' conclusions are essentially correct. However, Peters has been able to prove that under certain conditions the boundaries between adjacent interacting units are slightly curved rather than strictly linear.Matthews' procedures for determining optimal cutting unit size and shape have been widely used in the forest industry for 35 years. For regions where his assumptions are applicable (much of the southeastern and mid-KEY WORDS: Fores1 management, Timber harvesting, Cascading fixed charge structure, Mathematical programming, Computer simulation. Environmental Management, Vol. 4, No. 6, pp. 491~.98western US, and eastern Canada), there is little motivation to revise them. In many forested areas, however, these assumptions simply do not apply. One such area is the Douglas fir region of the Pacific Northwest. This region is characterized by rugged, non-uniform terrain and by timber that is distributed in type islands, or patches, rather than uniformly over the ground. As a result, logging costs are functionally related not only to the distance from the stump to the landing but also to the terrain and the distribu...