On the Ecology of Mountainous Forests in a Changing Climate: A ...

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164 Chapter 6 At the site Airolo (Fig. 6.5), spruce (P. excelsa), which is characteristic of montane mixed forests, is replaced by silver fir (A. alba), beech (F. silvatica), and other deciduous species under both climate scenarios. Comparing these results to the ones by Kienast (1991) is difficult because of the large sensitivity to species parameters in the FORECE model (cf. section 5.1), and further studies with the FORECE model would be required to allow for a meaningful comparison. At the site Bern (Fig. 6.5), only slight changes occur as compared to current climatic conditions. The major features of the current forests, especially the dominance of beech (F. silvatica) and silver fir (A. alba), remain characteristic also of future forests; under all scenarios, similar forest compositions are obtained. At Sion, major differences become evident concerning the physiognomy of the site under climatic change: While the IPCC scenario leads to steppification, a scrawny, low-biomass forest continues to exist under the Kienast scenario. Using FORECE, Kienast (1991) found that steppification may occur within 50 years after the onset of climatic change. Moreover, simulation results from FORCLIM-E/P/S under the regionalized scenario (A. Fischlin, pers. comm.) also project that forests would cease to grow at Sion. Hence, according to these simulation studies there is a considerable risk that sites close to the dry timberline may be confronted with forest dieback phenomena and steppification under climatic change. The behaviour of five forest models under the regionalized scenarios The simulation results from the five forest models at the sites Bever, Davos, and Bern are shown in Fig. 6.6. At the site Bever, the models produce strongly differing species composition under this scenario of climatic change. While the percentage similarity coefficient (PS, Eq. 2.3) between FORCLIM-E/P and E/P/S is 0.75, and PS = 0.85 between FORCLIM 1.1 and 1.3, there is little resemblance between these two groups and the FORECE species composition (PS < 0.4). At the site Davos, there are also considerable differences among the models, but they are more gradual than at Bever. The forest composition at the low-elevation site Bern exhibits the smallest differences among the five models (Fig. 6.6).
Model applications 165 Bever Biomass (t/ha) 400 200 * * = Pinus montana 0 ECE 1.1 1.3 2.4 2.4s Forest model Biomass (t/ha) 400 200 Davos Ulmus scabra Tilia platyphyllos Quercus robur Quercus petraea Populus nigra Fraxinus excelsior Fagus silvatica Castanea sativa Alnus viridis Acer pseudoplatanus Acer platanoides Pinus silvestris 0 ECE 1.1 1.3 2.4 2.4s Forest model Pinus cembra Picea excelsa Larix decidua Abies alba Bern Biomass (t/ha) 400 200 0 ECE 1.1 1.3 2.4 2.4s Forest model Fig. 6.6: Steady-state species compositions as simulated by various forest gap models under the same scenario of climatic change obtained by the downscaling methodology (Gyalistras et al. 1994, cf. Tab. 6.2). Symbols: ECE – FORECE model (Kienast 1987); 1.1 – FORCLIM version 1.1 (Bugmann & Fischlin 1994); 1.3 – FORCLIM version 1.3 (Bugmann & Fischlin 1994); 2.4 – FORCLIM-E/P, version 2.4 (this study); 2.4s – FORCLIM-E/P/S, version 2.4 (this study).
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Diss. ETH No. 10638 On the Ecology
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ii Table of contents A BSTRACT.....
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iv APPENDIX .......................
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vi Harald BUGMANN, 1994: On the eco
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viii Harald BUGMANN, 1994: Aspekte
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1 1 . Introduction 1.1 Climatic cha
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Introduction 3 1.2 Methods for the
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Introduction 5 in a changing climat
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Introduction 7 Their integrative ca
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Introduction 9 (1984) provides a mo
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Introduction 11 The main advantage
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13 2 . Analysis of existing forest
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Analysis of existing forest gap mod
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The forest model FORCLIM 45 carbon
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The forest model FORCLIM 47 TREE GR
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The forest model FORCLIM 49 gBFlag
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The forest model FORCLIM 51 Disturb
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The forest model FORCLIM 53 decay o
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The forest model FORCLIM 55 the est
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The forest model FORCLIM 57 3.3 Mod
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The forest model FORCLIM 59 Light a
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The forest model FORCLIM 61 Overall
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The forest model FORCLIM 63 D (cm)
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The forest model FORCLIM 65 a) b) c
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The forest model FORCLIM 67 Growth
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The forest model FORCLIM 69 Stress-
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The forest model FORCLIM 71 Tab. 3.
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The forest model FORCLIM 73 3.3.2 F
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The forest model FORCLIM 75 where k
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The forest model FORCLIM 77 NITROGE
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The forest model FORCLIM 79 peratur
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The forest model FORCLIM 81 of degr
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The forest model FORCLIM 83 microcl
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The forest model FORCLIM 85 Tab. 3.
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The forest model FORCLIM 87 3.4.3 F
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The forest model FORCLIM 89 All the
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The forest model FORCLIM 91 The mas
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The forest model FORCLIM 93 FORCLIM
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Behaviour of FORCLIM along a transe
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Page 107 and 108: Behaviour of FORCLIM along a transe
Page 115 and 116: Parameter sensitivity & model valid
Page 147 and 148: 153 6 . Model applications Climatic
Page 149 and 150: Model applications 155 The simulate
Page 151 and 152: Model applications 157 6.2 Possible
Page 153 and 154: Model applications 159 simulation s
Page 155 and 156: Model applications 161 Simulation e
Page 157: Model applications 163 At the site
Page 161 and 162: Model applications 167 tainty inher
Page 163 and 164: Model applications 169 scenario cho
Page 165 and 166: Discussion 171 Finally, the analysi
Page 167 and 168: Discussion 173 bitrarily chosen par
Page 169 and 170: Discussion 175 comparably small imp
Page 171 and 172: Discussion 177 end of the 21st cent
Page 173 and 174: Conclusions 179 Ecological factors
Page 175 and 176: Conclusions 181 species composition
Page 177 and 178: References 183 Begon, M., Harper, J
Page 179 and 180: References 185 Burger, H., 1951. Ho
Page 181 and 182: References 187 Faber, P.J., 1991. A
Page 183 and 184: References 189 Huntley, B. & Birks,
Page 185 and 186: References 191 Leemans, R. & Prenti
Page 187 and 188: References 193 Olson, J.S., 1963. E
Page 189 and 190: References 195 Rudloff, W., 1981. W
Page 191 and 192: References 197 Smith, T.M., Leemans
Page 193 and 194: References 199 Whittaker, R.H., 195
Page 195 and 196: Appendix 201 II. Derivation of para
Page 197 and 198: Appendix 203 Tab. A-4: Tree species
Page 199 and 200: Appendix 205 Tab. A-7: Values for m
Page 201 and 202: Appendix 207 The minimum winter tem
Page 203 and 204: Appendix 209 Tab. A-11: Shade toler
Page 205 and 206: Appendix 211 Tab. A-14: Climatic pa
Page 207 and 208: Appendix 213 IV. Source code of the
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Appendix 215 FROM SimBase IMPORT De
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Appendix 217 END; (* IF *) prevDay
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Appendix 219 PROCEDURE InitializeFW
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Appendix 221 InstallSeparator( fMen
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Appendix 223 FROM FCPFileIO IMPORT
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Appendix 225 modelSp^.p.kHm := sens
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Appendix 227 DeclMV( meanLitt[leafS
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Appendix 229 Swiss Federal Institut
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Appendix 231 (*********************
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Appendix 233 BEGIN WITH sp^ DO d :=
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Appendix 235 Definition module FCPB
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Appendix 237 Purpose Simulation mod
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Appendix 239 END Immobilization; PR
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Appendix 241 CONST lem = 3; VAR ef:
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Appendix 243 Purpose Provides the b
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Appendix 245 Example of a text file
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Appendix 247 Tab. A-15: Lower end o
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Appendix 249 Tab. A-17: Percentage
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Appendix 251 Tab. A-19: Significant
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Appendix 253 VI. Derivation of para
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Appendix 255 Tab. A-21: Species-spe
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Appendix 257 Tab. A-22 (continued)
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