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

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168 Chapter 6 Step climatic change Ramp climatic change Biomass (t/ha) 400 200 400 200 0 700 900 1100 Year 1300 0 700 900 1100 Year 1300 Biomass (t/ha) 400 200 0 700 Sigmoid climatic change 900 1100 Year 1300 Ulmus scabra Quercus robur Populus nigra Fraxinus excelsior Acer pseudoplatanus Acer platanoides Pinus silvestris Pinus cembra Picea excelsa Larix decidua Abies alba Fig. 6.8: Effect of various assumptions about the nature of transient climatic change between the simulation years 800 and 900 on the transient behaviour of FORCLIM-E/P at the site Bever (cf. Fig. 6.7). changes are not important because such a climatic change proceeds very fast compared to successional dynamics. Only the assumptions about the level of a hypothesized future constant climate are crucial (cf. Fig. 6.8). 6.2.3 Conclusion Several conclusions can be drawn from the simulation studies with various forest models under various climate scenarios developed to represent a hypothetical constant climate at the end of the 21st century: First, the species composition simulated by FORCLIM-E/P under various scenarios of climatic change at sites close to the alpine and the dry timberline differs markedly from the one simulated under current climatic conditions. This pattern is independent of the climate
Model applications 169 scenario chosen. However, the exact species composition simulated by FORCLIM-E/P at these sites and under climatic change depends strongly on the scenario used. On the other hand, sites at mid altitudes show smaller and more uniform changes of their species composition across the various climate scenarios. Second, similar effects are visible when evaluating the response of various forest models to one specific scenario of climatic change: The species composition simulated close to the alpine timberline varies considerably depending on the forest model used, i.e. on the number of factors incorporated in a model and their formulation. It is surmised that the same is valid also for sites close to the dry timberline, but this was not investigated in the present study. Sites at mid altitudes appear to be less sensitive to the choice of the forest model. Third, the uncertainty inherent in the regionalized scenario of climatic change leads to a wide array of possible future forest compositions. Thus, even if one climate scenario could be identified as the “best estimate”, its uncertainty would preclude precise statements about future forest composition and aboveground carbon storage, especially at subalpine sites. Finally, the comparison of step, linear (ramp), and sigmoid climatic changes during 100 years show that the choice of the transient scenario is not important because the change of the abiotic conditions proceeds fast compared to the successional dynamics. However, if climatic change continues for several centuries, i.e. when the time scale of climatic change approaches the time scale of forest succession (Bugmann & Fischlin 1994), the differences between the various scenarios of transient climatic change certainly would be more pronounced; as mentioned in the introduction to this section, there is no evidence that climatic change would come to a halt by the end of the next century. Moreover, these findings may not hold for changes of the variance of climatic parameters, which have not been investigated here.
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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 111 and 112: Behaviour of FORCLIM along a transe
Page 113 and 114: 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 and 158: Model applications 163 At the site
Page 159 and 160: Model applications 165 Bever Biomas
Page 161: Model applications 167 tainty inher
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
Page 209 and 210: Appendix 215 FROM SimBase IMPORT De
Page 211 and 212: 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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