EXECUTIVE SUMMARY - UNESCO World Heritage

70 NOMINATION DOSSIER "ANCIENT BEECH FORESTS OF GERMANY"
The beech has survived the
last ice age in southern
refuges in the Mediterranean
area. In the period that
followed the ice age, it
spread from the Dinaric
Alps to colonise Central
Europe. For it to reach
the Baltic Sea took several
millennia.
forest development that hazel, oak, elm, ash,
maple, and lime would advance. Th e mixed
oak forest period of the Atlantic was associated
with an increase in temperatures and
humidity. Dense mixed deciduous forests
would develop (POTT 1993). Th e climate
was already suitable for the beech’s expansion
8,000 years ago (GIESECKE et al. 2006).
However, some more millennia were to
pass before it reached the Baltic Sea, and even
more before it took hold as the dominant
tree species (WALTER & STRAKA 1970).
In the end, it was a temperature depression
at the beginning of the Subboreal period
some 5,000 years to a humid-cool climate
that promoted the beech’s mass expansion
(WALTER & STRAKA 1970).
A number of recent American studies have
furnished evidence of the climate's key
role in triggering the sudden, extremely rapid
geographical expansion of a population
(MAGRI et al. 2006).
Th e beech has only been taking hold in
Central Europe for a few millennia – which
is a very short period of time for the geological
perspective. Germany is the core
area of this ongoing ecological process, which
comprises the evolutionary development
of the complex and diff erent beech forest
ecosystems as well as the biotic moulding of
the Central European landscape.
Th e beech’s highly successful expansion can
be explained by its immense climatic plasticity,
wide ecological amplitude, and genetic
adaptability, which is why it is also called
“prevalence strategy”. Th e beech owes its
enormous competitiveness most notably to
its shade tolerance, which is characterised
by the growth rate being fl exibly adapted to
the light conditions based on leaf morphology,
sprout length, and branching type
(PETERS 1997). Beeches are, for example,
able to survive in the shade of the understorey
for more than 200 years, waiting for
a gap in the crown canopy to open which
would allow it to grow upwards and reach
the light (fi g. 2.16).
VISNJIC & DOHRENBUSCH (2004)
and CZAJKOWSKI & BOLTE (2006)
have demonstrated that occurrences of
Fagus sylvatica from diff erent climatic regions
show diff erent tolerances toward extreme
temperatures and aridity.
Recent genetic assessments have shown the
beech's postglacial colonisation of Central
Europe to have started from only a few
populations. Th e main thrust of expansion
as well as the development relevant for
Germany took its origin from the Dinaric
Alps and, to a lesser extent, from the Western
Alps and Western Carpathians. Th e populations
of the Pyrenean and Italian refuges
seem to have not contributed to colonisation
(MAGRI et al. 2006). However, expansion
cores for the Northwest Iberian beech
forests are considered to be the glacial refuge
areas of the Pyrenees (LOPEZ-MERINO
et al. 2008), and the South Italian refuges
for the Apennine Mountains (LEONARDI
& MENOZZI 1995).
Th e low mountain ranges of Germany, starting
with the Black Forest, Swabian Mountains,
and Bavarian Forest were colonised
from about 7,000 before present (POTT
1992). Th e beech arrived at the northern loess
areas by 6,500 before present. From there,
it has probably spread to adjacent siliceous
sites and the montane zone. About 3,800
years ago, it reached the coastal region of the
North Sea and the Baltic young moraine
along the Baltic Sea, and Jasmund 800 years
later (LANGE et al. 1986).
While the Late Glacial period (until 10.000
years ago), the beech covered 6% of its
current range in few isolated refuge areas. In
the mid Holocene (5,000 years ago) the