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

Appendix 201
II.
Derivation of parameters for European tree species
sType parameter
The sType parameter serves two purposes:
First, it separates evergreen (coniferous) from deciduous species; the two types differ in
the specific leaf area (the foliage area per unit foliage weight, parameter kC 2 ), and the dry
to wet weight ratio of foliage (parameter kC 1 ). Values for these parameters were derived
based on a large data set covering 8 species (Abies alba, Picea excelsa, Pinus silvestris,
Pinus cembra, Pinus montana, Larix decidua, Fagus silvatica, Quercus spp.) in Burger
(1945-1953). The data by Mitscherlich (1970, p. 28) was also evaluated, but it was concluded
that the Burger data provided a more reliable basis for estimating these parameters.
Second, it describes the relationship between diameter at breast height (D) and foliage
weight of the species. These relationships were derived based on Burger (1945-1953) as
well. Because of the scarcity of data on other species, five relationships were defined
from the Burger data, and the remaining species were assigned to one of these classes
based on their capability to cast shade as described by Ellenberg (1986, p. 82) and on the
values of the parameters A1 and A2 used in the FORECE model (Kienast 1987).
Specific leaf area and dry to wet weight ratio
Regression analyses of foliage area vs. foliage weight showed large correlation coefficients,
whereas the intercepts were not significantly different from zero (α = 5%) for all
species except for Quercus spp., where the intercept differs from zero at α = 0.002
(Tab. A-2). The slope for evergreen (coniferous) species varies between 5.1 and 6.6
[m 2·kg -1 ]; thus a value of kC 2 = 6 m 2·kg -1 was used. For deciduous species, the range
of the slope is 10.1 to 14.9 [m 2·kg -1 ]; a value of kC 2 = 12 m 2·kg -1 was used.
Tab. A-2: Regression analysis of foliage area (gFolA) vs. foliage wet weight (L) according to the equation
gFolA = i + kC 2·L, dry to wet weight ratio of foliage (kC 1 ), and sample size (n) from Burger (1945-
1953).
Species i kC 2 r 2 kC 1 n
Pinus silvestris 0.24 5.50 0.983 0.386 210
P. montana 2.29 5.95 0.989 0.489 18
P. cembra -2.59 6.64 0.994 0.408 4
Picea excelsa -0.51 5.27 0.979 0.478 56
Abies alba -1.47 5.09 0.987 0.465 52
Fagus silvatica 9.78 14.89 0.948 0.363 91
Larix decidua 6.67 10.05 0.984 0.366 99
Quercus spp. 17.41 10.07 0.983 0.362 51
The dry to wet weight ratio for deciduous trees shows small variability between the
species (Tab. A-2); a value of 0.35 was used. For evergreen species, variability is larger
and the average dry to wet weight ratio is 0.445; thus a value of 0.45 was used.
Derivation of a relationship between foliage weight and DBH
The analysis of the species-specific data in Burger (1945-53) indicated that several
species have similar relationships between foliage wet weight (L) and diameter at breast
height (D). Thus, these species were grouped. Tab. A-3 gives the regression formulae
obtained for four species/species groups, plus an additional species group having low foliage
weight (e.g. Betula, Salix), for which kA 1 was set arbitrarily 20% lower, i.e. to