Environmental Engineering Reference
In-Depth Information
Biogeography
Ioannis N. Vogiatzakis
6.1 Introduction to mountain biogeography
Mountains are hotspots of biodiversity worldwide (Myers et al., 2000; Korner and
Spehn, 2002). They support a large number of endemic species, as well as be-
ing centres of origin of important crops (Hamilton and McMillan, 2004). Due to
their altitudinal range, mountains exhibit over a few kilometres of vertical distance
climatic regimes that can be observed along longitudinal or latitudinal gradients
in lowland areas. Therefore they support a wide range of vegetation formations
demonstrating a distinct zonation. In addition to the diverse vegetation resulting
from steep environmental gradients, there are also many ecotones between these
zones. The direct influence of orogenesis on biogeography is twofold: it has created
a mosaic of habitats and acted as a barrier to migration. Additional habitat-creating
factors include landforms, hydrology and soils. The terrain in mountain environ-
ments is highly fragmented and diverse topographically. Mountain hydrology also
contributes to beta diversity due to the presence of glaciers, seasonal snow cover,
ice and seasonally frozen ground (Nagy and Grabherr, 2009).
Mountains are often located on the borders of different biogeographical regions,
and the Mediterranean mountains are no exception. Located at the crossroads of
three continents their flora comprises different phytogeographical elements rang-
ing from Euro-Siberian to Arctic-Alpine, to Irano-Turanian in the eastern Mediter-
ranean, as particularly demonstrated in the mountain flora of Crete, Cyprus and
Turkey (Table 6.1). Mediterranean mountain floras share common characteristics
in origin, lifeform and morphology as well as common genera and species. How-
ever, local species composition is related to biogeography, the length and degree
of isolation and speciation. In the Mediterranean the north-south floristic affinities
are stronger than those of east-west. This is also reflected in the dominant species
in the altitudinal belts of the region (Quezel and Medail, 2003). The Mediter-
ranean mountains host many regional and local endemic species, some of which
are relicts of past biogeographical patterns (Medail and Verlaque, 1997). In partic-
ularly the presence of Tertiary relictual vegetation is evident in the mountains of
Search WWH ::




Custom Search