Environmental Engineering Reference
In-Depth Information
Table 6.1
Percentage frequencies of different phytogeographical elements in the mountain
flora of Greece
Cosmopolitan
14.3
11.5
14.8
17.1
19.4
16.9
20.2
21.8
Central and S. European
7.8
13.5
16.1
18.7
21
17.3
21
22
Balkanic and Anatolian
12.9
13
9.9
8.4
8.2
12.9
8.8
12
Mediterranean
14.7
15.2
13
13.8
11.1
19.8
10.9
10.8
Balkanic and Italian
2.8
4.4
4.9
7.1
6
4
4.8
2.9
Balkan endemic
2.3
11.5
14.9
20.2
21.9
18.3
22.4
20.2
Greek endemic
6.5
16.3
15.4
9.5
5.6
5.8
4.5
2.4
Single area endemic
24.4
5.7
3.6
0.3
1.4
0
0.1
0.8
Single mountain endemic
11.1
4.4
2.5
0.2
1.1
0
3.7
3.2
Other
3.2
4.5
4.9
4.7
4.3
5
3.6
3.9
Total number of species*
217
540
751
609
780
278
868
665
Reproduced from Strid (1993).
*Absolute number.
Morocco, Greece, Lebanon and southwest and southeast Turkey (Quezel and
Medail, 2003). In a recent study, Medail and Diadema (2009) identified 33 moun-
tainous areas within 52 refugia in the Mediterranean Basin. Some of these moun-
tains had already been identified as regional biodiversity hotspots (Medail and
Quezel, 1997) and global centres of plant diversity (Table 6.2) (Davis
et al.,
1994)
Geology is another factor that contributes to biodiversity richness. The associ-
ation of lithologies with plants is one of the major factors determining plant and
community distribution patterns in mountain environments. The diversity of par-
ent material gives rise to a rich flora but also to specialized plants as demonstrated
by the limestone flora of Mount Olympus in Greece and the Taurus Mountains of
Turkey, or the serpentinophilous flora of Troodos in Cyprus and the siliceous flora
of the Baetic Ranges in Spain (Mota
et al.,
2002).
Although species richness follows the general rule whereby increases in alti-
tude are characterized by a decrease in richness, this relationship is not monotonic
and there are rich pockets of habitats. Another rule that applies in mountain ar-
eas, that of the increase in endemism as the altitude increases, is a consequence
of past isolation and resulting speciation. In biogeography, mountain tops have of-
ten been considered as similar/analogous to islands since they provided refuge to
arctic-alpine species during the interglacial periods: 'Terrestrial or continental habi-
tat islands (MacArthur & Wilson) are these relatively small areas of land or water
surrounded by, and isolated from, larger ecologically similar areas by an extensive
area of dissimilar habitat' (Tivy, 1993, p. 258).
Plants become smaller as the altitude increases, a result of harsher conditions at
higher zones. The main limiting factors, typical of mountain environments, are low
