This reprinting of the User's Guide to the Prognosis Model describes the Prognosis Model as released in September, 1981 (Version 4.0). Although we will soon release version 5.0, most of the material in this guide will remain applicable to the new version. There will be, however, modifications in the small tree growth models and in the crown-dubbing and crown-changing procedures that improve model behavior. These modifications will necessitate revisions of pages 52, 65-67, and 77-80.These revisions, and descriptions of new features, are contained in a supplement to this guide that will be released with the new version. The new features include:-A regeneration establishment component;-SHRUB and COVER extensions;-An event monitor for dynamic activity scheduling;-A classification algorithm used to shorten the tree record list by combining like records;-Expansion of management options.We have endeavored to make changes in such a way that the procedures for using version 4.0 will operate the same way in version 5.0.

This paper describes a set of computer programs for combining quantitative silvicultural knowledge with past growth data from a sampled stand to make a prognosis of the course of development that the forest stand is expected to follow under alternative management prescriptions. An important design criterion of this procedure is that the prognosis model should apply to stands containing any mixture of species or age and size classes that grow as a community. The model simulates the deviation-amplifying aspect of the growth process by a unique procedure for introducing the stochastic elements in a deterministic computing algorithm. The growth rates predicted by the built-in models for diameter change are compared to the actual past growth of the sample trees to calibrate these models for the particular stand for which the prognosis is to be computed. Selection of trees to be cut at any period can utilize a variety of tree characters to emulate a wide range of silvicultural prescriptions.An application of these programs to develop prognoses for lodgepole pine stands in the presence of an infestation of mountain pine beetles is described.

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the same way in version 5.0. December 1983 THE AUTHORS RESEARCH SUMMARY WILLIAM R. WYKOFF is a research forester with the Station's quantitative analysis of forest management practices and resources for planning and control research work unit at Moscow, Idaho. Mr. Wykoff received his B.S. in forest management (1970) from the University of Minnesota, St. Paul, and his M.S. in forest management (1975) from Washington State University, Pullman. Since joining the Station in 1974, he has worked on the development of tree growth models and the implementation of these models into the Stand Prognosis system. NICHOLAS L. CROOKSTON is a research associate, College of Forestry, Wildlife and Range Sciences, provided excellent technical reviews. The research support staff in Moscow endured both fickleness and changing technology, and processed each revision with more good humor than could be expected. In addition, personnel from National Forest Systems and from industry within the Inland Empire have used the Prognosis Model and early versions of documentation for about 7 years. In this period there has been considerable feedback leading to new options and revisions of the models and documentation. Finally, we would like to thank colleagues at the Forestry Sciences Lab in Moscow and cooperators at the University of Idaho for contributing to the development and testing of models.

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