This is the third annual compendium of a Technical Session of the Physiology Working Group of the Society of American Foresters held at the National Convention. Specialists in a dedicated area of tree physiology were invited to prepare chapter contributions synthesizing the status of knowledge in their area of expertise. Plant growth regulators (PGRs) was selected as the topic for in-depth examination at the 1986 Technical Session because a knowledge of how these "secondary messengers" regulate tree morphogenesis is vital to applications of biocontrol and biotechnology. Plant growth regulators have been the subject of numerous reviews in recent years. However, few have dealt specifically with woody perennials, and they are generally confined to single processes and/or organs. This volume attempts to provide a more comprehensive treatise of PGRs as they influence various ontogenetic events in forest trees. Reproductive physiology, both sexual and asexual, is emphasized because of its relevance to current efforts directed at increasing efficiency in the breeding and production of genetically improved trees for reforestation. The chapters on vegetative growth will be of interest to silviculturists and urban foresters as they consider cultural treatments in the management of forests and individual trees for specific products and purposes. This book should serve as a valuable text and source of reference for students, researchers and other professionals interested in gaining a better understanding of PGRs. The reader, however, who expects definitive answers to how PGRs function or can be used to control specific processes is likely to be disappointed.

This is the third annual compendium of a Technical Session of the Physiology Working Group of the Society of American Foresters held at the National Convention. Specialists in a dedicated area of tree physiology were invited to prepare chapter contributions synthesizing the status of knowledge in their area of expertise. Plant growth regulators (PGRs) was selected as the topic for in-depth examination at the 1986 Technical Session because a knowledge of how these "secondary messengers" regulate tree morphogenesis is vital to applications of biocontrol and biotechnology. Plant growth regulators have been the subject of numerous reviews in recent years. However, few have dealt specifically with woody perennials, and they are generally confined to single processes and/or organs. This volume attempts to provide a more comprehensive treatise of PGRs as they influence various ontogenetic events in forest trees. Reproductive physiology, both sexual and asexual, is emphasized because of its relevance to current efforts directed at increasing efficiency in the breeding and production of genetically improved trees for reforestation. The chapters on vegetative growth will be of interest to silviculturists and urban foresters as they consider cultural treatments in the management of forests and individual trees for specific products and purposes. This book should serve as a valuable text and source of reference for students, researchers and other professionals interested in gaining a better understanding of PGRs. The reader, however, who expects definitive answers to how PGRs function or can be used to control specific processes is likely to be disappointed.

Maintaining or increasing stand productivity is the concern of forest land managers worldwide. Consequently, there is increasing interest in understanding the impact of environmental stress on productivity and the development of management strategies that ameliorate or reduce the deleterious effects. Invited scientists gathered in Fort Collins, Colorado on July 30, 1985, to present the current state of knowledge regarding the impact of environmental stress on forest stand productivity. Particular attention was given to elucidating the mode of action by which individual stress elements reduce productivity. Environmental factors and the levels that constitute stressed (suboptimal) conditions in forest stands were identified, and the effects of stress intensity and duration on key stand parameters, including photosynthesis, respiration, assimilate partitioning, senescence and mortality, were emphasized. The role of genetics and silvicultural treatments in lessening the stress impact on stand productivity was presented, particularly in regards to alternative methods for environmental stress management. Modeling of stand dynamics in response to environmental stress was explored as an effective research and management tool. VIII Improved forest management practices will develop as we improve our understanding of the nature of important environmental stresses and as we comprehend their impact on tree and stand performance, manifested through physiological processes and genetic potential. This book is dedicated to such an understanding and comprehension.