An active co-operation between forest ecologists and physicists has continued for decades at the University of Helsinki. These scientists have the common vision that material and energy fluxes are the key to a proper understanding of natural phenomena. The authors of this book come from very different disciplines: tree ecophysiology, silviculture, aerosol physics, meteorology, soil science, chemistry, microbiology, botany and applied electronics. However, the shared vision has resulted in coherent research which crosses the disciplinary bounders and has produced an integrated programme covering a range of temporal and spatial scales.

The measurements at two long-term stations SMEAR I and II have been designed to study material and energy fluxes over forests at two geophysical locations. The result is a unique data set, providing insights into the climatological control of the carbon cycle in coniferous forests of northern Europe. The analysis starts from the space and time element level and is extended via ecosystems to boreal forests. The predictive power of the several theories proposed is high.

There are several crucial feedbacks from forests to the climate system. The mechanisms for those feedbacks are elaborated in the book: they involve changes in the carbon cycle, albedo, N2O emissions and the production of aerosols. Much of this work is new and the feedback relationships have not yet been incorporated into models of the climate system.

The book will be an important introduction for students and climate modellers alike, providing conceptual tools and ideas that are broadly applicable to terrestrial systems

Zusammenfassung
The Forest Primary Production Research Group was born in the Department of S- viculture, University of Helsinki in the early 1970s. Intensive ?eld measurements of photosynthesis and growth of forest vegetation and use of dynamic models in the interpretation of the results were characteristic of the research in the group. Electric instrumentation was based on analogue techniques and the analysis of the obtained measurements was based on self-written programs. Joint research projects with the Research Group of Environmental Physics at the Department of Physics, lead by Taisto Raunemaa (19392006) started in the late 1970s. The two research groups shared the same quantitative methodology, which made the co-operation fruitful. Since 1980 until the collapse of the Soviet Union the Academy of Finland and the Soviet Academy of Sciences had a co-operation program which included our team. The research groups in Tartu, Estonia, lead by Juhan Ross (19252002) and in Petrozawodsk, lead by Leo Kaipiainen (19322004) were involved on the Soviet side. We had annual ?eld measuring campaigns in Finland and in Soviet Union and research seminars. The main emphasis was on developing forest growth models. The research of Chernobyl fallout started a new era in the co-operation between forest ecologists and physicists in Helsinki. The importance of material ?uxes was realized and introduced explicitly in the theoretical thinking and measurements.

Inhalt

Methodologies.- Environmental Factors.- Transport.- Structure.- Processes.- From Processes and Transport to Trees, Ecosystems and Atmosphere.- Connections Between Processes, Transport and Structure.- MicroForest.- Interactions Between Boreal Forests and Climate Change.- Concluding Remarks.