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

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58 Chapter 3 TREE ESTABLISHMENT All the ecological establishment factors are formulated as boolean variables that allow (value = 1) or prevent (value = 0) establishment. The symbols used in the establishment submodel of FORCLIM-P are given in Tab. 3.2. Winter temperature The influence of low winter temperatures on sapling establishment rates is formulated according to the descriptions by Ellenberg (1986), Woodward (1987), and Prentice & Helmisaari (1991), i.e. sapling establishment is assumed to be impossible if winter temperature (uWiT) is below a species-specific threshold temperature (kWiT s ): gWFlag s = 0 uWiT < kWiT s 1 else (3.1) Tab. 3.2: Symbols used in the establishment submodel of FORCLIM-P. “Eq.” denotes the number of the equation where state and auxiliary variables are calculated. Factor Symbol Unit Explanation Eq. Winter temperature gWFlag s – boolean auxiliary variable 3.1 kWiT s °C minimum winter temperature tolerated Light availability gLFlag – boolean auxiliary variable 3.2 gAL 0 %/100 light availability at forest floor (height 0 meters) 3.18 kThres s %/100 threshold for establisment 3.3 kL y,s [1..9] light requirement of tree saplings Browsing gBFlag s – boolean auxiliary variable 3.4 gBrP s %/100 mortality due to browsing 3.4 kBrow s [1..3] browsing susceptibility kBrPr [0..10] browsing intensity Degree-day range gDFlag s – boolean auxiliary variable 3.5 kDDMin s °C⋅d minimum annual degree-day sum kDDMax s °C⋅d maximum annual degree-day sum Immigration gIFlag s – boolean auxiliary variable 3.6 kImmYr s yr simulation time of first occurrence of the species Establishment gP Est,s %/100 probability of establishment 3.7 kEstP s %/100 establishment probability parameter kEstNr #·m -2·yr-1 maximum rate of tree establishment kInitDBH cm initial diameter at breast height of tree saplings kPatchSize m 2 size of a forest patch
The forest model FORCLIM 59 Light availability If available light at the forest floor (gAL 0 , calculated according to Eq. 3.18) drops below a species-specific threshold (kThres s ) defined as a fraction of full sunlight, sapling establishment is prevented according to Eq. 3.2 & 3.3: gLFlag s = 0 gAL 0 < kThres s 1 else (3.2) where the species-specific threshold kThres s is calculated according to Ellenberg (1986, Fig. 3.5 left) based on the parameter kL y,s , which denotes the light requirements of saplings (“young trees”) on a nominal scale in the range [1..9]: kThres s = 0.025·(kL y,s –1) kL y,s < 5 0.1·kL y,s - 0.4 else (3.3) Browsing pressure The constant browsing intensity simulated in the FORECE model (Kienast 1987) was modified in a simple way which allows to explore the possible effects of varying browsing intensities on sapling establishment rates (Fig. 3.5 right): 0.50 1.0 kThres s 0.25 s gBrP 0.8 0.6 0.4 0.2 kBrow s = 3 0.00 1 3 5 kLys 7 9 0.0 -0.2 0 kBrow s = 1 5 10 kBrPr Fig. 3.5: Factors influencing sapling establishment. Left: The threshold parameter kThres s (% of full sunlight) is a function of the species parameter kL y,s (Eq. 3.3). Right: The probability that establishment is prevented (gBrP s ) depends on browsing pressure (kBrPr) and the susceptibility to browsing of the tree species (kBrow s ).
Page 1: Diss. ETH No. 10638 On the Ecology
Page 4 and 5: ii Table of contents A BSTRACT.....
Page 6 and 7: iv APPENDIX .......................
Page 8 and 9: vi Harald BUGMANN, 1994: On the eco
Page 10 and 11: viii Harald BUGMANN, 1994: Aspekte
Page 13 and 14: 1 1 . Introduction 1.1 Climatic cha
Page 15 and 16: Introduction 3 1.2 Methods for the
Page 17 and 18: Introduction 5 in a changing climat
Page 19 and 20: Introduction 7 Their integrative ca
Page 21 and 22: Introduction 9 (1984) provides a mo
Page 23 and 24: Introduction 11 The main advantage
Page 25 and 26: 13 2 . Analysis of existing forest
Page 27 and 28: Analysis of existing forest gap mod
Page 39 and 40: The forest model FORCLIM 45 carbon
Page 41 and 42: The forest model FORCLIM 47 TREE GR
Page 43 and 44: The forest model FORCLIM 49 gBFlag
Page 45 and 46: The forest model FORCLIM 51 Disturb
Page 47 and 48: The forest model FORCLIM 53 decay o
Page 49 and 50: The forest model FORCLIM 55 the est
Page 51: The forest model FORCLIM 57 3.3 Mod
Page 55 and 56: The forest model FORCLIM 61 Overall
Page 57 and 58: The forest model FORCLIM 63 D (cm)
Page 59 and 60: The forest model FORCLIM 65 a) b) c
Page 61 and 62: The forest model FORCLIM 67 Growth
Page 63 and 64: The forest model FORCLIM 69 Stress-
Page 65 and 66: The forest model FORCLIM 71 Tab. 3.
Page 67 and 68: The forest model FORCLIM 73 3.3.2 F
Page 69 and 70: The forest model FORCLIM 75 where k
Page 71 and 72: The forest model FORCLIM 77 NITROGE
Page 73 and 74: The forest model FORCLIM 79 peratur
Page 75 and 76: The forest model FORCLIM 81 of degr
Page 77 and 78: The forest model FORCLIM 83 microcl
Page 79 and 80: The forest model FORCLIM 85 Tab. 3.
Page 81 and 82: The forest model FORCLIM 87 3.4.3 F
Page 83 and 84: The forest model FORCLIM 89 All the
Page 85 and 86: The forest model FORCLIM 91 The mas
Page 87 and 88: The forest model FORCLIM 93 FORCLIM
Page 89 and 90: Behaviour of FORCLIM along a transe
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Behaviour of FORCLIM along a transe
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Parameter sensitivity & model valid
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153 6 . Model applications Climatic
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Model applications 155 The simulate
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Model applications 157 6.2 Possible
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Model applications 159 simulation s
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Model applications 161 Simulation e
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Model applications 163 At the site
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Model applications 165 Bever Biomas
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Model applications 167 tainty inher
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Model applications 169 scenario cho
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Discussion 171 Finally, the analysi
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Discussion 173 bitrarily chosen par
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Discussion 175 comparably small imp
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Discussion 177 end of the 21st cent
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Conclusions 179 Ecological factors
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Conclusions 181 species composition
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References 183 Begon, M., Harper, J
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References 185 Burger, H., 1951. Ho
Page 181 and 182:
References 187 Faber, P.J., 1991. A
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References 189 Huntley, B. & Birks,
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References 191 Leemans, R. & Prenti
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References 193 Olson, J.S., 1963. E
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References 195 Rudloff, W., 1981. W
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References 197 Smith, T.M., Leemans
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References 199 Whittaker, R.H., 195
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Appendix 201 II. Derivation of para
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Appendix 203 Tab. A-4: Tree species
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Appendix 205 Tab. A-7: Values for m
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Appendix 207 The minimum winter tem
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Appendix 209 Tab. A-11: Shade toler
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Appendix 211 Tab. A-14: Climatic pa
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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
Page 251 and 252:
Appendix 257 Tab. A-22 (continued)
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