Ecology and regeneration of forest communities on the alluvial fan ...

-Discussion-
3 3 0 m
N W S E
2 8 0 m
l o a m y g r o u n d
G R A V E L
l o a m y g r o u n d
Fig. 5.5 Cross section <strong>of</strong> the lower fan
Soil texture seems to have a lower importance. It may range from coarse to fine. The
slight correlation between Populus alba st<strong>and</strong>s <strong>and</strong> a relatively high carbonate content,
revealed by both DCA is rather due to its restriction to young, bare <strong>and</strong> thus more
carbonate rich soils than to its preference for carbonate (Rothmaler et al. 2002). Neither
Populus alba nor Populus nigra seem to be good competitors in mixed st<strong>and</strong>s. While
dominance within their own <strong>communities</strong> is explicit (Fig. 4.8. <strong>and</strong> Fig 4.16), they hardly
appear within the other <strong>communities</strong>. This is also mentioned by Johnson (2000). While
younger stages <strong>of</strong> Populus alba <strong>forest</strong> are light <strong>and</strong> fairly monospecific, few old <strong>and</strong>
huge Populus alba individuals within the Fraxinus excelsior-Pterocarya pterocarpa <strong>and</strong>
the Oplismenus undulatifolius-Acer velutinum community seem to be remnants <strong>of</strong> the
aforementioned open riverbed <strong>communities</strong>, still surviving because <strong>of</strong> lacking light
competition within the upper tree layer. The largest <strong>of</strong> them grow up to 50 metres <strong>and</strong>
count with circumferences <strong>of</strong> about ten metres. The other <strong>communities</strong> are located with
more distance to the riverbed, where the direct flood impact is lower <strong>and</strong> sedimentation
processes predominate due to the decelerated water flow. The Quercus iberica-
Carpinus orientalis community occupies large parts <strong>of</strong> the upper fan down to about 350
metres (Fig. 5.1 <strong>and</strong> Fig. 5.3). According to the DCA it is the community with the
highest correlation to higher located fan-sites, which means with the best adaptations to
survive drier conditions, like in the fairly hot summer. Different authors describe similar
<strong>forest</strong>s st<strong>and</strong>s in former Yugoslavia (Dinic et al. 1980) <strong>and</strong> also in Azerbaijan as
thermophile <strong>forest</strong> st<strong>and</strong>s adapted to relatively dry conditions (Missouri Botanical
Garden 2009).
-<strong>Ecology</strong> <strong>and</strong> <strong>regeneration</strong> <strong>of</strong> <strong>forest</strong> <strong>communities</strong> on the alluvial fan near Qakh (Northwestern Azerbaijan)-
41