Lichens of Crete
The first lichen
collections from Crete were reported
by
Zahlbruckner (1906). Some years later, Steiner (1916, 1919) published
on
collections made by Ginzberger and during an excursion of the university of Vienna.
A larger number of specimens were collected by Rechinger during a
longer stay
on the island. These collections were determined and published by
Szatala
(1943a). These prior results were the basis for the first checklist by
Kleinig
(1966) who listed some 330 species, including 80 new records.
Additional
information was contributed by Rondon (1969), and is scattered
throughout the
literature. In this compilation we tried to screen the literature
completely,
and also included data from various other collectors and some of our
own
collections.
Crete
has a rather central location in the Mediterranean, and is, together
with its
surrounding small islets, the southernmost island complex of Europe.
It is also the fifth-largest island in the Mediterranean with an area
of 8729
square kilometers (after Sicily, Sardinia, Cyprus,
and Korsika). The main island has a significant East-West orientation
and
measures 254 km in this direction, whereas its width is only 12 km at
its
narrowest and 56 km at its broadest point. The natural subdivision of
the
island is determined by its mountain systems, the Lefka Ori (2453 m),
the
Psiloritis (2456 m), which have snow cover c. until June, and the lower
systems, e.g. the Dikti mountains towards the east, and on the Sitia
peninsula,
the Orno ridges and the Afendis-Kavousi mountains (1476 m). Amidst the
larger
mountain systems, three highland plains (polje) are found: the Omalos,
Lassithi, and Nida plains. The mountains ridges are steep at their
southern
ridges towards the Lybian sea, and interrupted by deep gorges, with Samaria as the
most
famous one. Several small islands surround Crete: Gramvoussa,
Pontikinisi, Dia,
Dyonisiades in the North, and Gavdos (i.e. the southernmost point of Europe), Paximadia, Chrisi, and Koufonisi in the
South.
Crete is the remaining part of a
larger geological folding system originating from the oligocene, which
connected the Peloponnes with the mountains of West
Anatolia. This is part of the European plate, which is
raised
while the African plate moved underneath to the north beginning with
the
Cretaceous. A geological map was provided by Creutzberg et al. (1977).
Phyllite-quartzites, with a richly developed lichen diversity, are the
oldest
metamorphic rocks on the island (at least 300 mio years ago) and mainly
found
in the western parts. A completely different lichen flora is found on
platey
limestones and crystalline limestones, which are otherwise dominating
in the
mountains and contributing to karst phenomena. The late tertiary to
neogenic
marl, sandstones and clays, are mainly found in the lowlands. Natural
concretes, such as breccia and conglomerate, can be of any date, even
less than
50 years old. The unstable structure of these substrates does not
support a
well developed lichen flora.
Crete
is characterized by a typical Mediterranean climate and influenced by
different
winds. In winter, the accompanying rains of the mainly western winds
are the
reason why Western Crete gets most of
the
precipitation, whereas the eastern and southern parts are more dry. A
warm wind
from the South, called Notia, which transports dust from Sahara,
sometimes interferes in winter. In summer, relatively strong and cool
winds
from the North, the Etesian winds, may occur. Frost is rare in the
lowlands,
whereas the mountains get snow down to 1600 m in winter, which persists
often
until May. Rainfalls start in September to November, and reach their
maximum in
December and January. In June to August, even the mountain rarely get
some
rain. Fog is encountered mainly in northern exposed parts of the
mountains. The
often strong rains, which are not kept by the soil, are of little use
for the
vegetation in general. However, in the valley systems in the West, they
contribute to higher humidity.
The vegetation is mostly eumediterranean
and large closed forests are missing, contrasting Homer and Theophrast,
who
characterized Crete as an island with
‘rich
woodland’. However, it is difficult to estimate what exactly was
understood
under that term and unfortunately pollen deposits are rare. Rather
dense
chestnut platane stands, often with oak are still found in the western,
more
humid part of the island. Large parts of the island, including the
understorey
of the woodlands are, however, influenced by grazing animals, and there
is hardly
any undisturbed locality. Open vegetation is mostly garigue (phrygana)
or
steppe, well developed maquis is only found in the valleys of the
western
parts. Rondon (1969) provided some notes on common lichen habitats in Crete. This could be added by a few aditional
observations: Thorny cushion plants are an interesting microhabitat for
lichens
at higher altitudes. Apart from this, Castanea
plantations in Western Crete proved
to be
lichenologically interesting, especially in shaded gorges. Although the
understorey
and even branches of the trees are heavily degraded by goat grazing,
interesting oceanic species, such as Degelia
plumbea or various Bacidia
species, are found here.
The list
References
2. April
2008, Martin
Grube