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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Parameter sensitivity & model validation 151<br />
300<br />
SW Georgia (E/P)<br />
Ulmus spp.<br />
Quercus spp. (S)<br />
250<br />
Quercus spp. (N)<br />
Prunus serot<strong>in</strong>a<br />
Biomass (t/ha)<br />
200<br />
150<br />
100<br />
P<strong>in</strong>us spp.<br />
Nyssa sylvatica<br />
Liriodendron tulipifera<br />
Liquidambar styraciflua<br />
Ilex opaca<br />
Frax<strong>in</strong>us spp.<br />
Fagus grandifolia<br />
50<br />
Celtis laevigata<br />
Carya spp.<br />
0<br />
0<br />
400<br />
Year<br />
800<br />
1200<br />
Acer spp.<br />
Fig. 5.13: Simulation results from FORCLIM for Southwest Division, Georgia.<br />
The results presented above were based on <strong>the</strong> FORCLIM-E/P model; <strong>the</strong> simulations conducted<br />
with FORCLIM-E/P/S revealed only small differences concern<strong>in</strong>g <strong>the</strong> steady-state<br />
species composition <strong>of</strong> <strong>the</strong> simulated forests, although <strong>the</strong> simulated transient behaviour<br />
differed to some extent, especially for <strong>the</strong> sou<strong>the</strong>rn locations. There <strong>the</strong> abundance <strong>of</strong><br />
species such as Liquidambar styraciflua, Liriodendron tulipifera, and Nyssa sylvatica is<br />
reduced if nitrogen availability is modelled explicitly, which is due to <strong>the</strong>ir <strong>in</strong>tolerance <strong>of</strong><br />
<strong>the</strong> low nitrogen availability dur<strong>in</strong>g early succession (cf. section 4.3). <strong>On</strong> <strong>the</strong> o<strong>the</strong>r hand,<br />
<strong>the</strong> biomass <strong>of</strong> P<strong>in</strong>us spp. <strong>in</strong>creased considerably under <strong>the</strong>se conditions.<br />
5.4.4 Conclusion<br />
The application <strong>of</strong> <strong>the</strong> FORCLIM model along a latitud<strong>in</strong>al gradient <strong>in</strong> eastern North<br />
America and <strong>the</strong> comparison <strong>of</strong> <strong>the</strong> results with those obta<strong>in</strong>ed by Solomon (1986) and<br />
with descriptions <strong>of</strong> near-natural forests <strong>of</strong> <strong>the</strong> area (Rowe 1972, Küchler 1975) reveals<br />
several <strong>in</strong>terest<strong>in</strong>g features:<br />
First, FORCLIM successfully simulates <strong>the</strong> general pattern observed <strong>in</strong> <strong>the</strong> landscape, i.e.<br />
<strong>the</strong> transition from tundra to <strong>the</strong> boreal forest down to nor<strong>the</strong>rn deciduous forests. However,<br />
<strong>the</strong> model misrepresents <strong>the</strong> <strong>in</strong>creased <strong>in</strong>fluence <strong>of</strong> drought on forest structure when