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

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102 Chapter 4 a nitrogen availability (uAvN) of 100 kg/ha was assumed at all sites. The simulation results of the FORCLIM-P model are shown in Fig. 4.6 & 4.7. They will be discussed for each site in turn: At the site Bever (Fig. 4.6), the FORCLIM-P model simulates a larch (Larix decidua) – spruce (Picea excelsa) forest. Swiss stone pine (Pinus cembra) is of minor importance only, although it should dominate according to Ellenberg & Klötzli (1972). The same happens at the northern slope (not shown), so that forests in Bever according to FORCLIM-P exclusively belong to the Larici-Piceetum. At Davos (Fig. 4.6), FORCLIM-P correctly simulates a larch-spruce forest with some Swiss stone pine (P. cembra) as well as Scots pine (Pinus silvestris). The occurrence of black poplar (Populus nigra) may represent an anomaly; this species should be competitive on wet soils only (Hess et al. 1980). In the FORECE model, P. nigra was excluded by the static soil moisture indicator concept (Kienast 1987), which was omitted in FORCLIM (cf. section 2.3.1). Simulation results at the site Bern (Fig. 4.7) are characterized by a strong dominance of beech (Fagus silvatica), accompanied by silver fir (Abies alba), Norway spruce (P. excelsa), maple (Acer spp.), and black poplar (P. nigra). Especially during early succession, oak (Quercus petraea, Q. robur) are important species. This pattern conforms more to the descriptions by Ellenberg & Klötzli (1972) than the forest simulated by FORECE, which was dominated by beech, silver fir, maple, and linden (Tilia spp.). In the FORECE simulations, oak was not present at all, and maple (especially A. platanoides) was too abundant (Kienast 1987). In FORCLIM-P, silver fir may be too abundant, but it is less so than in FORECE. Tab. 4.4: Litter production [t·ha -1·yr -1 ] of the FORCLIM-P model simulated in isolation, averaged from the model output between the simulation years 1000 and 1200 (200 patches). Symbols: uFL – foliage litter (1 = fast, 2 = medium, 3 = slow decay); uTL – twig litter; uWL – stemwood litter; a.g. – aboveground; uRL – fine root litter. Site uFL1 uFL2 uFL3 uTL uWL total a.g. uRL Bever N 0.02 0.05 1.3 0.8 1.9 4.1 5.5 Bever S 0.02 0.06 1.2 0.8 1.4 3.5 5.0 Davos 0.02 0.3 1.1 0.8 2.1 4.3 5.8 Bern 0.22 2.0 0.05 1.0 4.4 7.7 9.2 Sion 0.02 1.5 0.04 0.6 4.4 7.7 9.2 Locarno 0.23 2.2 0 1.0 4.8 8.2 9.7
Behaviour of FORCLIM along a transect in the European Alps 103 The results obtained from FORCLIM-P at the site Sion do not correspond to phytosociological expectations (Fig. 4.7): Although this site is very xeric, an extremely high biomass is attained; while the occurrence of Q. robur is plausible (Ellenberg 1986), the codominance of chestnut (Castanea sativa) may be questionable, and the considerable biomass of yew (Taxus baccata) is unrealistic as well. The litter production simulated by FORCLIM-P is summarized in Tab. 4.4. In coniferous forests, leaf litter of low quality is produced (uFL 3 ), whereas deciduous forests are characterized by more easily degradable leaf litter (uFL 2 ). There is some literature data to evaluate the simulated pattern of total aboveground litterfall: For boreal forests (comparable to the sites Davos and Bever), Ajtay et al. (1979) give 5.5–6 t·ha -1·yr-1 , while their value for temperate forests (Bern, Sion, Locarno) is 8.5 t·ha -1·yr-1 ; the rates simulated by FORCLIM-P are slightly lower. On the other hand, Cox et al. (1978) found only 3.3 t·ha -1·yr-1 in a Liriodendron forest in Tennessee. For coarse woody debris (corresponding roughly to uWL), Harmon et al. (1986) list a range of 0.17–7 t·ha -1·yr-1 in coniferous forests, and up to 14.5 t ha -1·yr-1 in deciduous forests. The simulated aboveground litter production (Tab. 4.4) agrees with the range of data from these sources (cf. also Vogt et al. 1986). 4.3.2 FORCLIM-E/P In this model setup, the abiotic environment is stochastic; thus, it is not restricted to average conditions but includes some of the natural variability of the weather and the habitat. As in section 4.3.1, available nitrogen is kept constant at 100 kg/ha. The results of these simulations are shown in Fig. 4.8 & 4.9. At the site Bever (Fig. 4.8), the spruce forest simulated by FORCLIM-P (Fig. 4.6) is replaced by the Larici-Pinetum cembrae, where P. cembra dominates (Ellenberg & Klötzli 1972). Picea excelsa is not competitive any more due to the occurrence of summer droughts. On northern slopes at Bever (Fig. 4.12), a larch-spruce forest is simulated, corresponding to the pattern observed in the area (Ellenberg & Klötzli 1972). The forest simulated at the site Davos (Fig. 4.8) does not differ much from the one simulated by FORCLIM-P (Fig. 4.6); it still belongs to the Larici-Piceetum (Ellenberg & Klötzli 1972). Silver fir (Abies alba) occurs now because winter temperature in some years is high enough to enable establishment of the species. Its presence at elevations
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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
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 and 52: The forest model FORCLIM 57 3.3 Mod
Page 53 and 54: The forest model FORCLIM 59 Light a
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
Page 95: Behaviour of FORCLIM along a transe
Page 115 and 116: 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
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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
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Appendix 257 Tab. A-22 (continued)
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