For about 40 years 1 have been engaged in timberline research. Thus, one could suppose that writing this book should not have been too difficult. It was harder, however, than expected, and in the end 1 feIt that more questions had arisen than could be answered within its pages. Perhaps it would have been easier to write the book twenty years aga and then leave the subject to mature. But the late Prof. Heinz Ellenberg convinced me to portray a much needed and complete pieture of what we know of the timberline with special respect to its great physiognomie, structural and ecological variety. The first version of this book was published in the German language (Holt­ meier, 2000). An extensive summary and translated figure and photo cap­ tions and table headings were added to enable non-German speaking people to make use of the book as weIl. Nevertheless, 1 was very delighted when Prof. Martin Beniston encouraged me to prepare an English edition for the series "Advances in Global Change Research", which will guarantee a wider circulation.

Inhalt

Preface. Acknowledgements. 1: Introduction. 2: History and Present State of Timberline Research. 2.1. Early timberline research. 2.2. Modern timberline research. 3: Definitions, Terminology. 4: Physiognomic and Ecological Differentiation of Timberline. 4.1. Tree species at timberline. 4.2. Relationship of timberline elevation to macroclimate, climate character, and the mass-elevation effect. 4.3. Ecological conditions and processes at the timberline. 4.3.1. Heat deficiency. 4.3.2. Carbon balance. 4.3.3. Freezing and frost drought. 4.3.3.1. Frost tolerance and damages. 4.3.3.2. Frost drought. 4.3.4. Soil temperature. 4.3.5. Wind. 4.3.6. Snow cover. 4.3.6.1. Distribution and characteristics of snow cover. 4.3.6.2. Effects of the snow cover on sites. 4.3.7. Soils. 4.3.8. Topography. 4.3.8.1. Slope gradient and geomorphic structure. 4.3.8.2. Exposure. 4.3.9. Regeneration. 4.3.9.1. Seed-produced regeneration. 4.3.9.2. Vegetative reproduction. 4.3.10. Influence of site conditions on growth form. 4.3.11. Influence of trees and free stands on site conditions. 4.3.12. Anthropogenic impact on timberline. 5: Timberline Fluctuations. 5.1. Approach to past and present changes. 5.2. Conclusions and perspectives. References. Index.