This book provides the information necessary to understand and use the forest growth model. It describes some aspects of forested ecosytems and the ecology of trees. It sets the forest model within the broader context of the science of ecology and ecological theory and issues that confront society in the management of forests. It may serve as a prototype for approaches to other renewable natural resources issues. The current version of the model is keyed to this book; it is a available on diskettes for use on microcomputers, so that the reader can use and test the model. My purposes in writing this book are three: to place the model within the development of the science of ecology; to provide an explanation of the JABOWA model so that readers can understand the model, use it, test it, and develop their own extensions and modifications of it; and to suggest what might be and what is not likely to be possible in the development of theory for complex ecological systems. It is not my purpose to provide a complete literature review of all the derivatives of the original model. While this could be useful, it might confuse the reader who is trying to understand one version of the model. Therefore for the sake of clarity I have focused the discussion on the two major versions I have developed and used myself. This restriction is in no way meant to detract from the progress made by other investigators in their use of the model and their development of variants of it. In the last chapter, I attempt to relate my use of the model to the work of others and Appendix VII provides a list of references to many of these work as well as to related studies. I would like to acknowledge my appreciation to all the people who have used and extended the model and who recognize the connections between their versions and the original JABOWA model. The wide application of the model is a tribute to its strength and utility. Because there has been widespread use and adaptation of the JABOWA model, some readers may be interested in a brief history and a family tree. The original model was developed in 1970 as a summer research project by James Janak, James Wallis, and me under a cooperative agreement between the IBM corporation and Yale University. By the end of the summer the first version of the model was operating, and our initial presentation was made that same year (Botkin, Janak, and Wallis, 1970). To my knowledge, most computer models developed since then that are known as "gap-phase" models of forests are derived from the original JABOWA model, mainly along one of two family trees. These have been given a variety of names, including CLIMACS, FIRESUM, FORET, FORENA, LINKAGES, SILVA, ZELIG. John Aber, then a graduate student at Yale, worked with me to develop a version of the model that incorporated soil nitrogen effects; we applied this model to questions about ...
564 (Voraussage des Zuwachses) 568 (Andere zahlenmäßige Untersuchungen der Bestandesstruktur und ihrer Veränderungen. Wachstumsgang nach Baumklassen usw.)
