On the Ecology of Mountainous Forests in a Changing Climate: A ...
On the Ecology of Mountainous Forests in a Changing Climate: A ...
On the Ecology of Mountainous Forests in a Changing Climate: A ...
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The forest model FORCLIM 83<br />
microclimatic differences, which may be especially important <strong>in</strong> <strong>the</strong> subalp<strong>in</strong>e zone where<br />
direct radiation is considerably higher than at lower altitudes.<br />
F<strong>in</strong>ally, drought stress (uDrStr) is calculated <strong>in</strong> FORCLIM-E accord<strong>in</strong>g to Eq. 3.75; <strong>the</strong><br />
calculation <strong>of</strong> uAET y,l and PET y,l were described <strong>in</strong> detail by Fischl<strong>in</strong> et al. (1994).<br />
uDrStr = 1 – uAET y,l<br />
PET y,l<br />
(3.75)<br />
3.4 Parameter estimation<br />
3.4.1 FORCLIM-P<br />
The 30 tree species present <strong>in</strong> <strong>the</strong> model under European conditions were chosen based<br />
on Hess et al. (1980) and Kienast (1987). The derivation <strong>of</strong> <strong>the</strong> species-specific parameter<br />
values for <strong>the</strong>se species required a major effort, which is documented <strong>in</strong> Appendix<br />
II. The values f<strong>in</strong>ally obta<strong>in</strong>ed are given <strong>in</strong> Tab. 3.11, while <strong>the</strong> o<strong>the</strong>r parameter<br />
values are listed <strong>in</strong> Tab. 3.12 & 3.13. Some <strong>of</strong> <strong>the</strong> species-specific parameters <strong>in</strong><br />
FORCLIM-P were simplified by def<strong>in</strong><strong>in</strong>g species groups: A new species-specific parameter<br />
called sType (species type) was <strong>in</strong>troduced (Tab. 3.10). It serves <strong>the</strong> follow<strong>in</strong>g<br />
purposes:<br />
• First, it separates evergreen (coniferous) from deciduous species. This dist<strong>in</strong>ction<br />
is possible because all <strong>the</strong> species <strong>of</strong> a type behave similar <strong>in</strong> various respects:<br />
(1) <strong>the</strong> foliage area per unit foliage weight (parameter kC 2,s , Tab. 3.3),<br />
(2) <strong>the</strong> dry to wet weight ratio <strong>of</strong> foliage (kC 1,s , Tab. 3.3), and (3) <strong>the</strong> average<br />
retention time <strong>of</strong> foliage (kFRT s ; Tab. 3.5).<br />
• The second <strong>in</strong>formation conta<strong>in</strong>ed <strong>in</strong> <strong>the</strong> sType parameter is <strong>the</strong> type <strong>of</strong> relationship<br />
between diameter at breast height and foliage weight, thus replac<strong>in</strong>g <strong>the</strong><br />
parameters kA i,s (Tab. 3.3). Five species types were derived from an extensive<br />
analysis <strong>of</strong> <strong>the</strong> data by Burger (1945-1953).<br />
The rationale for <strong>the</strong> group<strong>in</strong>g <strong>of</strong> <strong>the</strong> species and <strong>the</strong> estimation procedure for <strong>the</strong>se parameters<br />
are described <strong>in</strong> Appendix II.