Some Questions Relating to the Age Dynamics of Boreal Forests

This manuscript is a result of discussions prior to and during the workshops "Impacts of Change In Climate and Atmospheric Chemistry on Northern Forest Ecosystems and Their Boundaries" (August 1987) and "Global Vegetation Change" (April 1988) and is an initial step in the development of a synthesis between realistic (e.g. biological-detail-rich) computer oriented models of forest and more mathematically, tractable, but simpler forest models. The work is focused on the boreal forests of the world (an important carbon reservoir and an important reserve of softwood timber). The boreal forests are also potentially strong impact systems under current scenarios of CO2-induced climate warming. One purpose of building a model is to get an understanding of what may happen to the climate if, for example, all of the boreal belt were to disappear, or if its functional efficiency were to double. Could such a disappearance occur simultaneously with changes in the tropical forests? How would this change the exchange between atmosphere and the earth surface? The authors try to describe a forest (or vegetation as a whole) as a boundary layer between fast atmospheric processes and slow processes in soil and underground water systems, and consider the geometry of canopies and roots as a function of extremes corresponding to a stable equilibrium of soil and underground water systems. The authors hope to consider these and similar problems during their continuing cooperation

Ecophysiological Models of Forest Stand Dynamics

It is well known that woodlands play a crucial role in stabilizing the natural environment. They greatly influence and regulate hydraulic cycles, and thus the flow of waters and local humidity conditions. They also filter air pollutants, thus protecting vulnerable soils and water bodies within forested watersheds. Therefore, as global belts of Boreal, Moderate and Tropical Forests actively take part in different biogeochemical and physical cycles in the biosphere, and play an extremely important role in the exchange of heat and moisture between the atmosphere and continents, an assessment of the forests in different time and spatial scales is of considerable value to the life of the human society. The systems approach permits us to look at these interrelationships in a comprehensive way and to see many negative and positive feedbacks which, together, provide a dynamical equilibrium of the waves in the all forest belts mentioned above (including others organic and inorganic waves, such as waves of insects, diseases, fires etc.). In the course of its existence IlASA has constantly been occupied with different aspects of the forest life. From time to time international working groups are formed on a IlASA base to examine the different aspects of the forest and forestry dynamics. The most recent example is a book on systems analysis of the Boreal Forest Dynamics, published by Cambridge University Press (Shugart et al., eds., September 1991). A group of American, European, Canadian and Soviet authors have worked together through a collaborative network. The products of the group include a general boreal forest model (which is currently being used to evaluate the potential effects of global climate change on the North American Boreal Zone); models on fire dynamics, seed dispersal, permafrost dynamics, herbivory and CO2 flux have been developed, providing a general modeling framework for simulating patterns and processes in the boreal zone. The present paper may be considered as some additional input to the problem, in the form of Ecophysiological Models, which were partially missing in the above-mentioned book. The paper partially intersects with the contents of the book, but from a different angle, especially as many papers considering the Russian view of the problem are added. The book on "System Analysis of the Boreal Forest Dynamics" and this outline stress the necessity of the development of a collaborative research effort to continue the development of computer models of the boreal forest (analogue to the GCM -- see, for example, Shugart, Bonan), and the so-called analytical models (analogue to the Global Average Models (GAM) -- see for example Antonovsky, Korzukhin) in response to environmental change. Assessments of anthropogenic stress on forests that show such complex dynamics are daunting. There is a clear need for a continuation of process-oriented comparative studies in polluted and non-polluted regions of the boreal forests to better understand these effects. It is clear from the reviews of actual observations and experimental evidence from the boreal forest and from the boreal forest models that the landscape response of boreal forests to stress is complex and not easily obtained from static measurements. Furthermore, the feedback complexities in the boreal forest ecosystem suggest that a multiple research program of experimentation, modeling and observation may lead to a better understanding of the forest dynamics under stress or novel situations than one-dimensional research programs

Realizing Opportunities in Forest Growth Modelling

The world is continually changing: the emergence of new technology and new demands for pertinent information pose new challenges and possibilities for forest management. Are forest growth models keeping up with client needs? To remain relevant, modelers need to anticipate client needs, gauge the data needed to satisfy these demands, develop the tools to collect and analyze these data efficiently, and resolve how best to deliver the resulting models and other findings. Researchers and managers should jointly identify and articulate anticipated needs for the future, and initiate action to satisfy them. New technology that offers potential for innovation in forest growth modelling include modelling software, automated data collection, and animation of model outputs. New sensors in the sky and on forest machines can routinely provide data previously considered unattainable (e.g., tree coordinates, crown dimensions), as census rather than sample data. What does this revolution in data availability imply for forest growth models, especially for our choice of driving variables

Vegetation Dynamics and Global Change

In the greenhouse debate, one of the most critical questions is how the world's forests will respond to a changing climate. This book introduces ecologists, environmentalists, foresters and earth scientists to the models which describe the forests and their rate of change. A number of techniques are available for projecting large-scale vegetation patterns, based on models incorporating fundamental biological mechanisms. This volume surveys the sophisticated mathematical and computational tools used in making predictions. Special attention is paid to the importance of scale in global studies. The chapters range from physiological phenomena typically measured at small scale to stand dynamics of forests, large-scale models of forest dynamics, the reconstruction of forest vegetation as a means of understanding current global change, and the role of forests in the global carbon cycle

Discriminant analysis of some east Tennessee forest herb niches. Environmental Sciences Division Publication No. 752

The purpose of this study was to evaluate the effectiveness of using discriminant analysis in assessing plant niches. As a component of research by the Environmental Research Park Project at Oak Ridge, Tennessee, five sites were inventoried for herbaceous species. From this inventory, four sympatric species of Galium and seventeen co-occurring herbaceous species were selected for discriminant analysis. The four species of Galium were treated as two data sets: one was composed of information collected at one site (a mesic hardwood area) and the other contained data from two cedar sites of shallow soil over limestone bedrock. The seventeen herbaceous species all occurred in the mesic hardwood area