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

134 Chapter 5
FORECE
Picea excelsa
T (°C)
P (mm/yr)
FORC LIM-E/P
FORC LIM-E/P/S
T (°C)
T (°C)
P (mm/yr)
P (mm/yr)
Fig. 5.4: Contour plot of Picea excelsa biomass [t/ha] as simulated by FORECE (top),
FORCLIM-E/P (bottom left), and FORCLIM-E/P/S (bottom right).
Comparing the distribution of several dominating tree species from Fig. 5.1 with the simulated
biomass distributions, it becomes evident that extremely steep gradients are characteristic
of FORECE: In this model, P. excelsa is excluded from the area where
T l < 2 °C although it should approach the upper timberline in moist areas (Fig. 5.4).
There is a similarly steep gradient of its biomass when approaching 5 °C. In both FOR-
CLIM variants, the species grows up to the alpine timberline (Fig. 5.4) and decreases
more smoothly towards higher temperatures, conforming to the phytosociological expectations
(Fig. 5.1). However, both FORECE and FORCLIM run into difficulties in the area
centered around 6 °C and 700 mm, where P. excelsa should dominate; both models exclude
this species due to the occurrence of strong droughts, which may be unrealistic. It
should be noted that FORECE predicts the occurrence of P. excelsa somewhat further into