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

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70 Chapter 3 LITTER PRODUCTION Two sources of litterfall are distinguished in FORCLIM-P. First, there is the annual production of litter by living trees, i.e. roots, twigs, and leaves. Second, there is the litter accumulating when a tree dies, which includes the above litter categories plus stemwood (Pastor & Post 1985). Litter production constitutes the output variables of the FORCLIM- P model (Fig. 3.2). The symbols used for calculating litter production are listed in Tab. 3.5. Litter production of living trees The quantity of foliage litter produced annually by each tree cohort (uFLL) is calculated from tree foliage weight (gFolW c ). It is assumed that each species produces leaf litter of one given quality; thus the leaf litter from a tree cohort is assigned to the appropriate group of litter according to the discrete parameter kLQ s (Pastor & Post 1985): uFLL kLQ, c = gFolW c · nAlive c kFRT s · kAshFree (3.35) where nAlive is the number of trees alive in the cohort, kFRT s is the average foliage retention time of the species, and kAshFree is a conversion factor to determine the ashfree weight of litter, i.e. its organic dry matter content. Twig litter (uTLL) is calculated based on a field study by Christensen (1977, as cited in Pastor & Post 1985), assuming that twig litterfall is proportional to basal area: uTLL c = π 4 · D c 2 · kConv · nAlive c · kAshFree (3.36) where kConv is a factor to convert basal area [cm 2 ] to twig litter [kg]. Only few measurements are available on the turnover of root litter (uRLL) in forest ecosystems (e.g. Waring & Schlesinger 1985, Kimmins 1987); thus roots were assumed to have a turnover rate proportional to the turnover rate of foliage (Pastor & Post 1985): uRLL c = kRSR · uFLL kLQ,c (3.37)
The forest model FORCLIM 71 Tab. 3.5: Symbols used for calculating litter production in FORCLIM-P. Factor Symbol Unit Explanation Eq. General kAshFree %/100 organic matter content of dry weight nAlive c – number of living trees per cohort nDead c – number of dead trees per cohort nTC – number of tree cohorts present on a patch Leaf litter production uFLL kLQ,c kg foliage litter from living trees (kLQ = 1,2,3) 3.35 uFLD kLQ,c kg foliage litter from dead trees (kLQ = 1,2,3) 3.38 gFolW c kg foliage weight 3.21 sType s – grouping parameter (cf. Tab. 3.10) kFRT s yr average time of foliage retention kLQ s [1..3] leaf litter quality (1 = fast, 3 = slowly decaying) Twig litter production uTLL c kg twig litter from living trees 3.36 uTLD c kg twig litter from dead trees 3.39 kConv kg·cm -2 conversion factor basal area → twig litter Root litter production uRLL c kg root litter from living trees 3.37 uRLD c kg root litter from dead trees 3.40 kRSR – root:shoot ratio of litter production Wood litter production uWLD c kg wood litter from dead trees 3.41 gSBio c kg dry stemwood biomass 3.42 The data base for European tree species was found to be too small to allow for speciesspecific root:shoot ratios (kRSR). Hence a common root:shoot ratio was assumed to be valid for all species (Waring & Schlesinger 1985). Litter from dead trees The same rationale as above is applied to calculate foliage litter (uFLD), twig litter (uTLD), and root litter (uRLD) of dead trees (Eq. 3.38-3.40): uFLD kLQ, c = gFolW c · nDead c · kAshFree (3.38) uTLD c = π 4 · D c 2 · kConv · nDead c · kAshFree (3.39) uRLD c = kRSR · uFLD kLQ,c (3.40) where nDead c is the number of dead trees in cohort c. The amount of woody litter (uWLD) produced by the dead trees of a cohort is calculated from stemwood biomass (gSBio c ) based on allometric relationships from Burger (1945-53), Sollins et al. (1973), and Woods et al. (1991):
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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
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 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: The forest model FORCLIM 69 Stress-
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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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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