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Silver fir (Abies alba Mill.) is a large conifer that can be found in central Europe and some parts of Southern and Eastern
Europe. It is one of the tallest tree species of the genus Abies in Europe. This tree is considered an important ecological
and functional balancer of European forests and a fundamental species for maintaining high biodiversity in forested
ecosystems. Its future distribution is subject of a debate between palaeoecologists and modellers, with contrasting
climate-response forecasts.
Silver fir (Abies alba Mill.) is a large evergreen coniferous tree
mainly distributed in montane areas in Central Europe, but is also
present in Southern and Eastern Europe. It is a distinctive tree,
straight-stemmed with a silver-grey trunk1. Growth is very slow in
early years, and then rapid as the tree matures. The uppermost part
of young trees has a conical shape gradually changing to become a
rounded dome as the tree grows older2. The needles are dark green
and glossy on their upper side while the lower side has two silvergreen waxy bands of 6-8 rows of stomata, and can live for up to six
or eight years. Flowers only appear after 30 to 40 years, generally
in April or May, and the buds are red-brown and non-resinous.
The fully developed seeds are mainly dispersed by wind. With
particularly cool and moist habitats this tree can live up to 500-
600 years3, 4 and reach heights above 60m4-7 making it among
the tallest tree species of the genus Abies in Europe. This tree is
also the most heavily browsed of the commercially important tree
species in montane forests of central and southeastern Europe8.
Distribution
Silver fir is often distributed on relatively high elevated areas
(500-2000m a.s.l.). It requires relatively high moisture conditions
throughout the year, with mean yearly precipitation between
700 and 1800mm9. Its main distribution is concentrated in
Central Europe, on the Suisse plateau and in South and Eastern
Germany as well as in the Czech Republic and Austria. There are
conspicuous numbers in the Pyrenees, Southern Alps of Northern
Italy and Ticino and the Eastern Alps, the Carpathians and Albania.
It is also found more sporadically in Eastern France, on the Massif
Central, and in the Apennines. Stands of silver fir are present
in the Dinaric Alps and are continuously connected towards the
Rodopi mountains in Bulgaria and Greece, where it naturally
hybridises with the Greek fir (Abies cephalonica) forming stable
populations of intermediate forms described as Bulgarian firs
(Abies x borisii-regis)
2. Plantations of silver fir are rare outside its
natural range, possibly because of increased potential for insect
damage in monocultures1.
Concerning its past distribution palaeo evidence suggests
different ice-age refugia of silver fir in northern, central and
southern Italy, the Balkans, the Pyrenees and potentially France,
which is in agreement with results obtained using biochemical
and molecular markers10. During the past decades silver fir
was positively responding to climate warming in Central Europe
and adjacent areas, as documented in many tree ring series11.
However, in Switzerland, silver fir is decreasing as a result of
animal browsing and replacement by Norway spruce (Picea
abies), a more economically valuable species12. The future
distribution of Silver Fir is subject of a debate. Some studies
suggest a reduction in response to future expected warming13, 14,
while others suggest stable conditions or expansions15, 16.
Habitat and Ecology
Silver fir tolerates a wide variety of soil types with different
nutrient content and alkalinity conditions except compact and
hydromorphic soils. Deep and moist but not too wet soils are
preferred with a pH from acid to neutral. Silver fir shows a
noticeable soil-acidifying ability15. Unlike the other European
and Mediterranean Abies species, it prefers cooler and moister
conditions, favouring summer temperatures ranging from
approximately 14°C to 19°C9. The main limiting factors are a
lack of summer heat and adequate moisture during the growing
season, while new seedlings are extremely sensitive to frost
damage. This tree is mostly found mixed with Norway spruce
(Picea abies) or Scots pine (Pinus sylvestris) at the upper tree
limit1, 4, 18. At lower altitudes it competes with beech (Fagus
sylvatica), being the first conifer species to appear among them4.
It is very shade tolerant and can remain as a “seedling bank”
under the canopy of older dominant trees for decades. It often
invades deciduous forests due to its easy natural regeneration.
Importance and Usage
Silver fir is considered an important ecological and functional
balancer of European forests and can serve as a keystone species
for maintaining high biodiversity in forested ecosystems9. The
wood is non-resinous, light and fine-grained and also easy to
work, which makes it a good material for carpentry and furniture.
During the seventeenth century, its wood was used to produce
ships’ masts. The essential oils obtained from the leaves were
also used in the past to heal bruises as well as for treating coughs
and colds1. Along with Norway spruce (Picea abies), silver fir is
also used for paper production. During the 19th century it was
popular as a Christmas tree, although it has lately been replaced
by the cheaper Norway spruce1.
Threats and Diseases
Silver fir is particularly susceptible to frost desiccation due
to late spring frosts. It is also very sensitive to fire19, 20, insects,
fungi and industrial emissions, in particular to sulphur dioxide
SO2
exposure during winter19. In the next decades the climate
of central and southern Europe is predicted to become warmer
and somewhat drier22, favouring diseases and plant pests. Insect
pests such as mistletoe and bark beetles have already been
responsible for a reduction of silver fir in the Mediterranean,
especially in those areas where drought stress is more frequent21.
The fungi Armillaria mellea agg. and Heterobasidion annosum
are responsible for butt rot and windthrow. Phytophagous insects
such as Mindarus abietinus and Dreyfusia normannianae are
often the cause of infections to needles and bark. Other insectssuch as Cinaria pectinatae and Epinotia nigricana are affecting
bark and buds2. Silver fir is vulnerable to Ips typographus which
is also associated to potentially harmful fungal assemblages24-26.
It is also a susceptible host to Dothistroma septosporum
and vulnerable to Gremmeniella abietina and Dothistroma
septosporum