Mountain Timberlines ADVANCES IN GLOBAL CHANGE RESEARCH VOLUME36 Editor-in-Chief MartinBeniston,UniversityofGeneva,Switzerland Editorial Advisory Board B. Allen-Diaz, Department ESPM-Ecosystem Sciences, University of California, Berkeley,CA,U.S.A. R.S. Bradley, Department of Geosciences, University of Massachusetts, Amherst, MA,U.S.A. W.Cramer,DepartmentofGlobalChangeandNaturalSystems,PotsdamInstitute forClimateImpactResearch,Potsdam,Germany. H.F.Diaz,ClimateDiagnosticsCenter,OceanicandAtmosphericResearch,NOAA, Boulder,CO,U.S.A. S. Erkman, Institute for communication and Analysis of Science and Technology– ICAST,Geneva,Switzerland R.GarciaHerrera,FaculateddeFisicas,UniversidadComplutense,Madrid,Spain M.Lal,CenterforAtmosphericSciences,IndianInstituteofTechnology,NewDelhi, India. U. Luterbacher, The Graduate Institute of International Studies, University of Geneva,Geneva,Switzerland. I. Noble, CRC for Greenhouse Accounting and Research School of Biological Science,AustralianNationalUniversity,Canberra,Australia. L.Tessier,InstitutMediterranéend’EcologieetPaléoécologie,Marseille,France. F.Toth,InternationalInstituteforAppliedSystemsAnalysisLaxenburg,Austria. M.M. Verstraete, Institute for Environment and Sustainability, Ec Joint Research Centre,Ispra(VA),Italy. Forothertitlespublishedinthisseries,goto www.springer.com/series/5588 Friedrich-Karl Holtmeier Mountain Timberlines Ecology, Patchiness, and Dynamics Prof. Dr.Friedrich-Karl Holtmeier Dionysiusstr. 6 48329 Havixbeck Germany ISBN978-1-4020-9704-1 e-ISBN978-1-4020-9705-8 LibraryofCongressControlNumber:2008942996 AllRightsReserved (cid:176)c 2009 SpringerScience+BusinessMediaB.V.Printedin2008,reprintedwithcorrectionsin2009. 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Printedonacid-freepaper 9 8 7 6 5 4 3 2 1 springer.com CONTENTS PREFACE vii ACKNOWLEDGEMENTS ix 1 INTRODUCTION 1 2 H ISTORY AND PRESENT STATE 5 OF TIMBERLINE RESEARCH 2.1 E arly timberline research 5 2.2 Modern timberline research 7 3 DEFINITIONS, TERMINOLOGY 11 4 PHYSIOGNOMIC AND ECOLOGICAL 29 DIFFERENTIATION OF MOUNTAIN TIMBERLINE 4.1 T ree species at timberline 29 4.1.1 Influence of geological and floral history 29 4.1.2 Tree species at temperate and northern timberlines 32 4.1.3 Tree species at timberlines in the southern hemisphere 42 and in the tropics 4.2 R elationship of timberline elevation to macroclimate, 49 c limate character, and the mass-elevation effect 4.3 E cological conditions and processes at the timberlines 58 4.3.1 Heat deficiency 58 4.3.2 Carbon balance, carbon limitation 61 4.3.3 Frost tolerance and damage 65 4.3.3.1 Temperate and northern timberlines 65 4.3.3.2 Tropical timberlines 73 4.3.4 Winter desiccation and abrasion 75 4.3.5 Soil temperature 86 4.3.6 Wind 104 4.3.7 Snow cover 107 v vi Mountain Timberlines 4.3.7.1 Distribution and characteristics of snow cover 108 4.3.7.2 Effects of the snow cover on sites 111 4.3.8 Soils 122 4.3.9 Topography/geomorphology 135 4.3.9.1 Slope gradient and geomorphic structure 136 4.3.9.2 Exposure 162 4.3.10 Regeneration 167 4.3.10.1 Seed-produced regeneration 167 4.3.10.2 Vegetative reproduction 182 4.3.11 Influence of site conditions on growth form 188 4.3.12 Influence of trees and tree stands on site conditions 220 4.3.13 Influence of animals on timberline 244 4.3.13.1 Large herbivorous mammals 245 4.3.13.2 Burrowing herbivorous mammals 253 4.3.13.3 Birds 254 4.3.13.4 Defoliating insects (Epirrita autumnata, 264 Operophtera brumata) 4.3.14 Anthropogenic impact on timberline 268 4.3.14.1 Lowering the timberline 268 4.3.14.2 After-effects of timberline decline and present 278 impact 5 TIMBERLINE FLUCTUATIONS 293 5.1 General aspects 293 5.2 Timberline fluctuations in the past 297 5.3 Driving processes and adverse factors controlling 299 present timberline dynamics 5.4 Regional variation in timberline response after the 301 ‘Little Ice Age’ 5.5 Conclusions and perspectives 326 6 TIMBERLINE PROSPECTS AND RESEARCH 335 NEEDS REFERENCES 343 INDEX 421 PREFACE For more than 40 years I 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 I felt that more questions had arisen than could be answered within its pages. Perhaps it would have been easier to write the book 30 years ago and then leave the subject to mature. Lastly it was the late Prof. Heinz Ellenberg who had convinced me to portray a much needed and complete picture of what we know of the timberline with special respect to its great physiognomic, structural and ecological variety. The first version of this book was pub- lished in the German language (Holtmeier, 2000). Nevertheless, I was very delighted when Prof. Martin Beniston encouraged me to prepare an English edition for the series ‘Advances in Global Change Research’, which guaranteed a wider circulation. Timberline is a worldwide and very heterogeneous phenomenon, which can only be presented by way of examples. My own field experience is necessarily limited to certain timberline areas, such as the Alps, northern Scandinavia, northern Finland and many high mountain ranges in the western United States and Canada. However, my own observations and the results of my and my previous collaborators research were essential for developing the concept of the book and became integrated into the picture of timberline that is presented in the following chapters. Since the most thorough-going study of the literature cannot compensate for lack of one’s own field experience and observation, the main discussion is focused on the timberline regions in the northern hemisphere where I have carried out extensive field research. Nevertheless, tropical timberlines and temperate timberlines in the southern hemisphere are also considered based on informa- tion from literature and on communication with colleagues. This book is a conclusive synthesis of my own and my collaborators studies, and the evaluation of a wealth of literature. The intellectual conception of this volume has not principally changed compared to its first English edition. However, since the first English edition of this book was published much new material has accumulated. I have incorporated relevant new results of timberline research and other useful information into this edition. The text has been partly reorganized. Moreover, I added a few photos and graphs. Several graphs have been modified. Different from the first edition, examples of the influence of animals on timberline are given now in separate chapters. The ample reference list has grown again to now vii viii Mountain Timberlines about 1.500 titles. However, in view of the worldwide existence of mountain timberline and of the many possible scientific approaches to timberline (botany, ecology, climatology, soil science, forestry, historical science, etc.) this list cannot be expected to be complete, and surely the reader will miss inclusion of one or another familiar publication. On the other hand, the references include many papers and books that were written in German. Anglophone researchers seldom or never refer to these papers. But these publications are reflecting a long tradition in timberline research by German speaking scientists and provide much useful information that I have tried to make available to those researchers not acquainted with the extensive 19th and 20th century publications written in German. I have also included older publications to show that many ideas on causes of altitudinal and northern timberlines are not as new as one might believe in view of the reference lists given in many recent papers citing only the most recent publications on the particular topic just being considered. As in the previous edition, instructive illustration has been kept up. It is part of the conception of this book. Most of the photos were taken in my special research areas. In addition, friends and colleagues provided a few pictures from timberline regions that I did not visit by myself. All my photos were taken exclusively for documentation of timberline, which means that they do not show landscapes where also timberline was portrayed more or less accidentally. Still as ever there is no other comparable timberline-specific photo collection. The illustration is to give a detailed picture of the great physiognomic variety of timberline, which also mirrors its heterogeneity and ecological variety. This should be underlined as in a time of increasing modelling the visual element has been generally neglected. I hope this book will contribute to better understand the interplay of the many factors causing mountain timberlines and their great variety and dynamics. Havixbeck, December 2008 Friedrich-Karl Holtmeier ACKNOWLEDGEMENTS This book could not have been written without revising by friends, col- leagues and collaborators. Although being retired for almost 5 years I still feel deeply obliged to my academic teacher Prof. Dr. Dr. h. c. Carl Troll (1899–1975, Institute of Geography, University of Bonn) and also to Prof. Dr. Ulrich Schweinfurth (1925–2005, Institute of Geography, South Asia Institute, University of Heidelberg). Both introduced me into the wide field of landscape ecology and particularly into timberline problems already when I was a student. My thanks also go to Prof. Dr. Dr. h.c. Joachim Blüthgen (1912–1973, Institute of Geography, University of Münster), himself a pioneer in northern tree line research, who gave me the first chance to carry out field research in northern Finnish Lapland in the late 1960s. Moreover, I gratefully remember my friend Prof. Dr. Paavo Kallio (1914–1992, Kevo Subarctic Research Institute, University of Turku) who watched my tree line studies in Lapland with great interest and provided use of all facilities at the Kevo Subarctic Research Station in northern Finnish Lapland. My special thanks go to those friends and colleagues who essentially contributed to developing the conception of this book or supported my fieldwork by their great hospitality and good company in the field. First of all I mention Prof. Dr. Gabriele Broll (Division of Geoecology, University of Vechta, Germany), Dr. James B. Benedict (Center for Mountain Archeology, Ward, Colorado), Mrs. Audrey DeLella-Benedict (Cloudy Ridge Naturalists, Ward, Colorado) and Dr. Wyman C. Schmidt (Research Scientist Emeritus, Intermountain Forestry Sciences Laboratory, Montana State University, Bozeman). I am also obliged to Dr. Maaike Y. Bader (Institute for Biology and Environmental Sciences, University of Oldenburg), Dr. Robert Brandes (Institute for Geography, University of Erlangen), Prof. Dr. Frank Klötzli (Institute of Geobotany, University of Zürich), Prof. Dr. Ernst Löffler (Physical Geography, University Saarbrücken), Prof. Dr. Hermann Mattes (Institute of Landscape Ecology, University of Münster), Prof. Dr. Richard Pott (Institute of Geobotany, University of Hannover), Dr. M. Daud Rafiqpoor (Institute of Geography, University of Bonn), Prof. Dr. Michael Richter (Institute of Geography, University of Erlangen), Prof. Dr. Udo Schickhoff (Institute of Geography, University of Hamburg), Dr. Hans-Uwe Schütz (Schöppingen), Dr. Andreas Vogel (Institute of Landscape Ecology, University of Münster) and Prof. Dr. Masatoshi Yoshino (Institute of Geography, Auchi University, Toyohashi-City, Japan). These colleagues provided me with pictures from timberlines that I did not visit myself. Not ix