Research Collection Doctoral Thesis On the interaction between atmosphere and vegetation under increasing radiative forcing a model analysis Author(s): Füssler, Jürg Stephan Publication Date: 1998 Permanent Link: https://doi.org/10.3929/ethz-a-002040376 Rights / License: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library Diss. ETH Nr. 12802 On the Interaction between Atmosphere and Vegetation under Increasing Radiative Forcing: A Model Analysis A dissertation submitted to the Swiss Federal Institute of Technology Zurich (ETHZ) for the degree of Doctor of Natural Sciences presented by Jtirg Stephan Fussier Dipl. Phys. ETH born 2 April 1968 citizen of Basel accepted on the recommendation of Prof. Dr. A. Wokaun, examiner Prof. Dr. F. Klotzli, co-examiner Dr. F. Gassmann, co-examiner 1998 Leer - Vide - Empty 1 Table of Contents Acknowledgements 7 Summary 10 Kurzfassung 12 Chapter 1 Introduction 15 Part I Background 19 Chapter 2 Models of Climate and Terrestrial Vegetation 21 2 1 The Climate System 21 2 1 1 Components and Interactions 21 2 1 2 Atmosphere-Vegetation Interactions 23 2 2 Models of Climate 29 2 2 1 Why Modelling Climate'' 29 2 2 2 A Hierarchy of Climate Models 31 2 2 3 Simple versus Complex Models 35 2 3 Models of Terrestrial Vegetation 37 2 3 1 Soil Vegetation-Atmosphere Transfer Schemes 37 2 3 2 Biogeochemical Models, Models of Carbon Fluxes 41 2 3 3 Gap Models 43 2 3 4 Biogeography Models, Models of Biome Distribution 43 2 3 5 Coupling between Models of Vegetation 44 2 4 Modelling Atmosphere-Vegetation Interaction 45 2 5 Problems in the Modelling of Atmosphere Vegetation Interaction 46 4 Part II The Conceptual Model 49 Chapter 3 A Conceptual Model of Local Atmosphere-Vegetation Interaction 51 Chapter 4 Model Part I: Surface Energy Balance 55 4 1 Introduction 55 4 2 Formulation of the Surface Energy Balance 55 4 3 Parameter Estimation 59 4 3 1 Short-wave Energy Balance 59 4 3 2 Long wave Energy Balance 61 4 3 3 Impact of Tempeiature and Biomass on Surface Fluxes 63 Chapter 5 Model Part II: Biomass Dynamics 67 5 1 Introduction 67 5 2 Formulation ot the Biomass Dynamics 68 5 3 Parametei Estimation 71 5 3 1 Biomass Gain and Loss 71 5 3 2 Impact of Temperature and Drought on Growth and Mortality 72 Chapter 6 Atmosphere-Vegetation Interaction with Dynamic Vegetation 77 6 1 Simulation Experiments 77 6 2 Results from the Basic Model 77 62 1 Transient Response to an Incieasing Forcing 77 6 2 2 Model Sensitivity 79 6 3 Discussion 86 Part III Model Extensions 89 Chapter 7 Model Extension I: Dynamics of Roots and Soil Water Availability 91 7 1 Introduction 91 7 2 Formulation of the Dynamics of Roots and Soil Watei Availability 92 7 3 Parameter / 93 M 7 4 Simulation Experiments 93 7 5 Results from the Model with Root Water Availability Feedback 94 7 5 1 Steady State Response 94 7 5 2 Response to a Perturbation in the Bistable Range 97 7 5 3 Model Sensitivity 97 7 6 Discussion '01 Chapter 8 Model Extension II: Cloud Feedback 105 8 1 Introduction 105 8 2 The Parameterization of Cloudiness 105 8 3 Parameter '/E' 106 8 4 Simulation Experiments 107 8 5 Results from the Model with Cloud Feedback 107 8 6 Discussion 109 5 Chapter 9 Model Extension III: Adaptation 113 9 1 Introduction 113 911 Adaptation and Pre-adaptation within a Species 113 9 1 2 Shifts in Vegetation Composition 114 9 1 3 Rooting Depth 114 9 2 Model Description 115 9 2 1 Adaptation Parameter 115 9 22 Adaptation in Roots and Mortality Rate 116 9 3 Parameter Estimation 117 9 4 Simulation Experiments 118 9 5 Results from the Model with Adaptation 118 9 6 Discussion 120 Chapter 10 Conclusions 123 10 1 A Conceptual Modelling Framework 123 10 2 Atmosphere-Vegetation Interactions Influence the Trajectory of Future Climate 124 10 3 How Fast Will the Terrestrial Vegetation Respond'' 125 10 4 Outlook 126 References 129 Appendix 143 A 1 Model Parameters 143 A 2 Alternative Model Parametenzations 145 A 2 1 Logistic Equation 145 A 2 2 Dependence of Growth Factor on Temperature 145 A3 List of Acronyms and Abbreviations 147 A 4 Model Code Implementation and Algorithms 148 A 5 Source Code 149 Curriculum Vitae 161 6 Acknowledgements 7 Acknowledgements I would like to express my gratitude to the many persons which, through the last three years, contributed in one or another way to the work presented in this the¬ sis. First, I would like to thank Prof. Alexander Wokaun at the Paul Scherrer Institute (PSI) for the support and supervision of the thesis, his interest in the conceptual model, his comments and ideas, and for the detailed review of the manuscript. The initial idea for this thesis is due to Dr. Fritz Gassmann at PSI. His knowl¬ edge and interest in the climate system with all its components, his enthusiasm in nonlinear dynamical systems in general, his confidence and assistance were very helpful and stimulating. He also carefully reviewed the manuscript. Other support at PSI came from Dr. Rolf Siegwolf, who proved to be a valua¬ ble help for the various biology-related questions that bothered the physicist, covering subjects from fine root growth to the processes of leaf shedding. Dr. Matthias Saurer gave valuable advice on tree rings and Yvonne Scheidegger assisted in the jungle of taxa. Dr. Paul Kesselring helped me to start at PSI, and Dr. Esmond Newson supported me with his British humour, excellent cookies and tea. I am deeply indebted to Prof. Frank Klbtzli at the Geobotanical Institute of the Swiss Federal Institute of Technology (ETHZ) in Zurich. His commitment and interest enabled a fruitful collaboration over the boundaries between 'phys¬ ics' and 'biology'. His broad experience and knowledge of the response of plant communities around the globe to climatic or other disturbances were an impor¬ tant input to the thesis, which he carefully reviewed. Dr. Harald Bugmann, then at the Potsdam Institute of Climate Impact Research (PIK), now at the National Center for Atmospheric Research (NCAR) in Boulder, CO, was a reliable and very valuable advisor for all questions regarding vegetation dynamics, the drafting of scientific papers, and the survival of Ph.D. students in general. The use of transect data was suggested by Prof. Wolfgang Cramer at PIK. Another valuable help regarding vegetation dynamics was Dr. Heike Lischke at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL). In Dr. Axel Kleidon, then at the Max Planck Institute for Meteorology in Ham¬ burg, now at Stanford University, CA, I found an expert of rooting systems and their dynamics, and an enthusiastic advocate of simple models. For the modelling of atmospheric processes, specially for the parameteriza¬ tion of the radiation balance and the surface fluxes, Andreas Roesch and Dr. Martin Wild at the Institute of Geography of ETHZ supported me with their great expertise and with data. In addition, they introduced me to the subtleties of 8 Acknowledgements the art of GCM simulation. My thanks go also to Dr. Richard Betts at the Had- ley Centre, Bracknell, UK, and Samuel Levis at the University of Wisconsin, MA, to whom I owe a profound insight in the progress and the problems of cur¬ rent studies of two-way coupling of atmosphere and vegetation in Global Circu¬ lation Models. Part of the work described in this thesis was carried out at the Collegium Hel- veticum, Interdisciplinary Research Institute of ETHZ. This fellowship was a very valuable and fruitful experience, which allowed me to put my scientific work into a much broader social and cultural context. I would like to thank Prof. Adolf Muschg, Prof. Yehuda Elkana, Prof. Helga Nowotny, Prof. Thomas P. Hughes, Brigitte Kronauer and all the colleagues and the staff at the Collegium Helveticum, specially Patricia Fry, Matthias Wachter and Priska Gisler, who reviewed parts of the thesis. Mathis Fussier designed the cover and improved the layout of the thesis. The financial support of the Paul Scherrer Institute, the Collegium Helveti¬ cum, and the Alliance for Global Sustainability is gratefully acknowledged. I would like to thank my family. Acknowledgements 9 10 Summary Summary Jurg Stephan Fussier, 1998 On the Inteiaction between Atmosphete and Vegetation undei Incieasinq Radiatne Foicinq A Model Analysts PhD thesis No 12802, Swiss Federal Institute of Technology Zurich (ETHZ), 161 pp Atmosphet e-^ eqetatwn inteiaction Terrestrial vegetation exerts a significant influence on the atmosphere For instance, it determines by its reflectivity (albedo) the input in shortwave energy from the sun, it controls the fluxes of water vapour and of carbon dioxide, and influ¬ ences by its surface roughness the flow in the planetary boundary layer In contrast, the struc¬ ture and functionality of the terrestrial vegetation are shaped to a large degree by the prevailing climatic conditions Terrestrial vegetation must therefore be seen as an integral and dynamic component of the climate system, which is linked to the atmosphere in a two-way interaction However, in current global climate models that are used to project the evolution of the glo¬ bal climate under an increasing greenhouse gas induced radiative forcing, the structure of ter restnal vegetation, which determines the properties and the functionality of the land's surface with respect to the atmosphere, is assumed to remain constant and not responsive to the changing climatic conditions First attempts to implement dynamic representations of