Master’s thesis CLIMATE-GROWTH RELATIONSHIPS IN MIXED FIR-SPRUCE STANDS IN THE WESTERN RHODOPES, BULGARIA GERHARD SCHMIED Master’s course Forestry and Wood Science Ecosystem Dynamics and Forest Management Group Technical University of Munich (TUM) Matriculation number: 03698312 Supervision: 1. SEBASTIAN KIENLEIN (TUM) 2. DR. PETIA NIKOLOVA (WSL) In collaboration with: Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) Department for Forest Resources and Management Institute of Biodiversity and Ecosystem Research (IBER) Department for Ecosystem Research, Environmental Risk Assessment and Conservation Biology Imprint Department Ecosystem Dynamics and Forest Management Group Technical University of Munich Hans-Carl-von-Carlowitz-Platz 2 85354 Freising Author Gerhard Johannes Michael Schmied Elisabethstraße 14 80796 München Keywords Climate-growth relationship, Picea abies, Abies alba, Dendroclimatology, mixed stands, Western Rhodopes Recommendation for citation SCHMIED, GERHARD (2020): Climate-growth relationships in mixed fir-spruce stands in the Western Rhodopes, Bulgaria. Master’s thesis. Technical University of Munich. Ecosystem Dynamics and Forest Management Group. Freising. Acknowledgments First, I would like to thank Sebastian Kienlein and Dr. Petia Nikolova for their extensive supervision. Dr. Peter Brang (WSL), Prof. Dr. Tzvetan Zlatanov (IBER) and Dr. Wolfgang Beck I would like to thank for their professional input and support and Dr. Martin Gutsch (PIK Potsdam) for the supply of the climate data. Last but not least, I would like to thank my family and friends for their unlimited support and motivation- especially my colleague Dominik Ambs, who conducted the field work with me and who brought in a lot of useful new ideas. Cover image Mixed fir-spruce (-beech) stand near Smolyan in the Western Rhodopes © Gerhard Schmied Table of contents Table of contents ............................................................................................................................................ I Table of figures ........................................................................................................................................... IV List of tables ..............................................................................................................................................VIII Abstract ....................................................................................................................................................... IX 1. Introduction ........................................................................................................................................... 1 1.1. Climate change, its impact on forest ecosystems and the possibility for assessment .................... 1 1.2. Silver fir and Norway spruce under climate change ...................................................................... 3 1.3. Aim of the study ............................................................................................................................ 6 2. Methodology and materials ................................................................................................................... 8 2.1. Study area ...................................................................................................................................... 8 2.1.1. Selection of the study region ................................................................................................. 8 2.1.2. Site selection .......................................................................................................................... 8 2.1.3. Tree selection ...................................................................................................................... 10 2.1.4. Climatic conditions .............................................................................................................. 11 2.1.5. Soil....................................................................................................................................... 14 2.2. Plot design description ................................................................................................................ 14 2.3. Assessment of the general stand information .............................................................................. 16 2.4. Assessing information for dendrochronological research ........................................................... 16 2.4.1. Description of the cored trees .............................................................................................. 16 2.4.1.1. Vitality and stability of the trees.................................................................................. 16 2.4.1.2. Social status and competition ...................................................................................... 17 2.4.2. Tree sampling ...................................................................................................................... 18 2.4.3. Core beam preparations and measurements ........................................................................ 19 2.5. Tree-ring analysis ........................................................................................................................ 20 2.5.1. Standardization .................................................................................................................... 20 2.5.2. Chronology building and basic assessment and statistics.................................................... 24 2.5.2.1. Chronology building .................................................................................................... 24 2.5.2.2. Basic chronology assessment and statistics ................................................................. 26 2.5.2.2.1. Expressed Population Signal (EPS) .......................................................................... 26 2.5.2.2.2. Signal-to-Noise Ratio (S/N, SNR)............................................................................ 27 2.5.2.2.3. Selection of the detrending method .......................................................................... 27 2.5.2.2.4. Mean sensitivity (MS) .............................................................................................. 28 2.5.2.2.5. Gleichläufigkeit (Glk) .............................................................................................. 28 I 2.5.3. Tree-Ring/ Environment interactions .................................................................................. 30 2.5.3.1. Pointer year analysis .................................................................................................... 30 2.5.3.2. Determination of extreme climatic events ................................................................... 31 2.5.3.3. Growth responses to disturbances ............................................................................... 32 2.5.3.4. Examination of climate-growth relationships using program CLIMTREG ................ 33 3. Results ................................................................................................................................................. 37 3.1. General site descriptions.............................................................................................................. 37 3.1.1. Inclination and exposition ................................................................................................... 37 3.1.2. Basal area ............................................................................................................................ 38 3.1.3. Height .................................................................................................................................. 39 3.1.4. Age ...................................................................................................................................... 40 3.1.5. Determination of yield capacity .......................................................................................... 41 3.2. Characterization of the sampling trees ........................................................................................ 41 3.2.1. Stability of the sampling trees ............................................................................................. 41 3.2.2. Competition ......................................................................................................................... 42 3.3. Dendroclimatological analysis .................................................................................................... 43 3.3.1. Course of the growth ........................................................................................................... 43 3.3.2. Growth fluctuations ............................................................................................................. 45 3.3.3. Chronology characteristics .................................................................................................. 47 3.3.4. Pointer year analysis ............................................................................................................ 51 3.3.5. Evaluation of possible extreme climatic events .................................................................. 53 3.3.6. Growth response to disturbance in 1987 ............................................................................. 55 3.3.7. Determination of the climate-growth relationship of P. abies and A. alba ......................... 59 3.3.7.1. Climate- growth relationship of