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

Parameter sensitivity & model validation 145
Tab. 5.5: Derivation of FORCLIM parameters for the tree species of eastern North America from the data
used in the models FORENA (Solomon 1986) and LINKAGES (Pastor & Post 1985).
Parameter(s) Transformation rule Reference
sType cf. Appendix VI Pastor & Post (1985)
kDm, kHm, kAm, kDrT none Solomon (1986)
kG
recalculated from equation developed in Solomon (1986)
Appendix II
kDDMin, kDDMax recalculated according to correction formula Solomon (1986)
developed in chapter 3
kWiT cf. Appendix VI Solomon (1986)
kNTol assigned from LINKAGES parameters Pastor & Post (1985)
kBrow “FALSE” = 1, “TRUE” = 3 Solomon (1986)
kLy, kLa “1” = 3, “2” = 7 Solomon (1986)
kLQ cf. Appendix VI Pastor & Post (1985)
5.4.2 Simulation experiments
At each of the 10 locations, 200 patches were simulated during 1200 years (cf. section
2.2.2). It should be noted that this is a much larger sample size and a longer time span
than the one used by Solomon (1986), who simulated only 10 patches over 400 years
with the current climate.
Both the FORCLIM-E/P and the FORCLIM-E/P/S models were run along the transect in
order to investigate the importance of explicitly modelling soil organic matter dynamics
and nutrient availability. At all locations a mesic silt loam with a field capacity (kFC) of
30 cm was simulated. For the model variant FORCLIM-E/P, nitrogen availability at all locations
was assumed to be 100 kg/ha. No disturbances such as windthrow or fire were
simulated. The steady-state species composition of the simulated forests was estimated by
averaging the output from the years 1000–1200 of each patch.
5.4.3 Results & discussion
TUNDRA-WOODLAND TRANSITION AND NORTHERN BOREAL FOREST
Fig. 5.10 summarizes the steady-state species compositions along the northern part of
the gradient. Only few and stunted trees grow at Churchill and Shefferville, correspond-