During the summer of 1987, a series of discussions I was held at the International Institute for Applied Systems Analysis (nASA) in Laxenburg, Austria, to plan a study of global vegetation change. The work was aimed at promoting the Interna tional Geosphere-Biosphere Programme (IGBP), sponsored by the International Council of Scientific Unions (lCSU), of which nASA is a member. Our study was designed to provide initial guidance in the choice of approaches, data sets and objectives for constructing global models of the terrestrial biosphere. We hoped to provide substantive and concrete assistance in formulating the working plans of IGBP by involving program planners in the development and application of models which were assembled from available data sets and modeling ap proaches. Recent acceptance of the "nASA model" as the starting point for endeavors of the Global Change and Terrestrial Ecosystems Core Project of the IGBP suggests we were successful in that aim. The objective was implemented by our initiation of a mathematical model of global vegetation, including agriculture, as defined by the forces which control and change vegetation. The model was to illustrate the geographical consequences to vegetation structure and functioning of changing climate and land use, based on plant responses to environmental variables. The completed model was also expected to be useful for examining international environmental policy responses to global change, as well as for studying the validity of IIASA's experimental approaches to environmental policy development.

During the summer of 1987, a series of discussions I was held at the International Institute for Applied Systems Analysis (nASA) in Laxenburg, Austria, to plan a study of global vegetation change. The work was aimed at promoting the Interna tional Geosphere-Biosphere Programme (IGBP), sponsored by the International Council of Scientific Unions (lCSU), of which nASA is a member. Our study was designed to provide initial guidance in the choice of approaches, data sets and objectives for constructing global models of the terrestrial biosphere. We hoped to provide substantive and concrete assistance in formulating the working plans of IGBP by involving program planners in the development and application of models which were assembled from available data sets and modeling ap proaches. Recent acceptance of the "nASA model" as the starting point for endeavors of the Global Change and Terrestrial Ecosystems Core Project of the IGBP suggests we were successful in that aim. The objective was implemented by our initiation of a mathematical model of global vegetation, including agriculture, as defined by the forces which control and change vegetation. The model was to illustrate the geographical consequences to vegetation structure and functioning of changing climate and land use, based on plant responses to environmental variables. The completed model was also expected to be useful for examining international environmental policy responses to global change, as well as for studying the validity of IIASA's experimental approaches to environmental policy development.

The response of forests to global climate change is one of the most hotly contested issues in the greenhouse effect debate. Much effort is being devoted to the construction of models which describe the function of the forests and their rate of change. There are a wealth of techniques available to project large-scale vegetation patterns, all based on different underlying models that contain fundamental biological and ecological mechanisms. Vegetation Dynamics and Global Change will introduce both students and professionals to the sophisticated mathematical and computational tools used to predict the rate of change in the world's forests. It emphasizes the importance of scale in global studies. Leaders in the field of vegetation modeling cover physiological phenomena typically measured at small time and space scales; the stand dynamics of forests; large-scale models of forest dynamics; the reconstruction of forest vegetation of past climates as a way to understand current global changes; and the role of forests in the global carbon cycle. Several themes run through the book, including the need to understand how processes important at one time and space scale can be conceptualized at larger scales; the need to optimize the conceptual benefits of representing processes in detail and the attendant difficulties of estimating parameters and designing tests for elaborate models; and the need to identify the most appropriate system variables.

The boreal forests of the world, geographically situated to the south of the Arctic and generally north of latitude 50 degrees, are considered to be one of the earth's most significant terrestrial ecosystems in terms of their potential for interaction with other global scale systems, such as climate and anthropologenic activity. This book, developed by an international panel of ecologists, provides a synthesis of the important patterns and processes which occur in boreal forests and reviews the principal mechanisms which control the forests' pattern in space and time. The effects of cold temperatures, soil ice, insects, plant competition, wildfires and climatic change on the boreal forests are discussed as a basis for the development of the first global scale computer model of the dynamical change of a biome, able to project the change of the boreal forest over timescales of decades to millennia, and over the global extent of this forest.

Predicting how terrestrial ecosystems might respond in the future to large-scale human-generated changes is a major challenge for ecologists. In Terrestrial Ecosystems in Changing Environments, Herman H. Shugart describes the fundamental ecological concepts, theoretical developments, and quantitative analyses involved in understanding the responses of natural systems to change. The key ecological concepts described include the ecosystem paradigm, niche theory, vegetation/climate relationships, landscape ecology and ecological modeling. A variety of ecological models are presented, and their applications in predicting responses to change are considered. The challenge of producing ecological models capable of predicting long-term and large-area ecosystem dynamics is reviewed and several examples are provided. Finally, some of the exciting new findings regarding terrestrial landscapes and their feedback with their climatic setting are discussed in the context of human land use and global change.

To the human eye, a forest is a slowly changing ecosystem that, superficially, looks alike from one year to the next. This seeming quiet though is a balance between the tremendous progenerative potential of trees and an equally tremendous mortality rate. The intrinsic nature of the trees that comprise a forest make it all but impossible to collect complete data sets on the dynamics of natural forests and our understanding of the long-term dynamics of forests is based largely on scientific inference. Because of this reliance on inference, mathematical models of forest dynamics offer a valuable formalization of what we believe to be the important mechanisms involved in forest succession. Originally published in 1984, A Theory of Forest Dynamics is intended for scientists and graduate students in ecology and forestry. The book includes: a review of ecologic succession; coverage of forest dynamics models and detailed analysis of several models of forest succession. Mathematic models of forest dynamics are inspected and evaluated. The models are applied to ecologic problems on scales ranging from small forest gaps to entire landscapes and over years to millennia. "Almost twenty years after its first publication, this book continues to be a highly valuable resource for forest ecologists, whether they are engaged in dynamic modeling or not. It provides a thorough, mathematically underpinned theory of forest succession with a large array of application examples. I am thrilled that this volume is available again." Dr. Harald Bugmann, Professor of Mountain Forest Ecology, ETH Zurich, Switzerland "Since this book was first published in 1984, it has been a seminal publication describing the ecological processes controlling the dynamics of forest ecosystems. The scientific relevance and importance of the book have only increased over time. In particular, as climate modelers now realize that terrestrial ecosystems are an important feedback in the climate system they are including dynamic vegetation models in their climate models. This allows vegetation to change as climate changes, feeding back to affect climate. Hank Shugart's book outlines the theory of forest dynamics needed to successfully include dynamic vegetation within climate models." Dr. Gordon Bonan, National Center for Atmospheric Research, Boulder, Colorado "Hank Shugart's book A Theory of Forest Dynamics has served as a "bible" in the field of forestry and ecology since its original publication in 1984. It made the forest gap model known world-wide, which led to the application of a large number of forest gap models to almost all forest types and continents. It has become a classic in forest science. Traditionally, forest science was regarded as a statistical and experienced science because trees could not be observed by a single person for an entire life span, making it impossible to predict the consequences of forest management, disturbances and environmental changes. The invention of the forest gap model quickly changed that situation because forest gap models can record, simulate and forecast the past, present and future in an understandable scale so that long term dynamics of forests may be understood based on a small group of hypothesis related succession factors: birth, mortality, growth under competition of light, water and space, parameterized by simple forestry inventory in forestry and forest ecology. A Theory of Forest Dynamics can be used both for research and teaching in forest science. It was written for scientists interested in forest science, but it has also been used as a textbook in computer modeling and forest ecology." Yan Xiaodong, Deputy Director, START TEA RRC, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing