Geoscience Reference
In-Depth Information
an important role in determining climate and
river morphology. Coastal rivers are generally
below 400 m in altitude, while inland, where
some mountain peaks exceed 2600 m in the
Cordillera Cant abrica, the steep, deep valleys
contain short torrential rivers with high erosive
power. Cantabria has a humid oceanic temperate
climate (average annual temperature 14
◦
C) and an
average annual precipitation of about 1200 mm.
Rainfall is regularly distributed throughout the
year with winter and spring maxima. Storms can
occur at any time and snow is common from late
autumn to early spring in the mountains.
The high altitude range produces a marked
vegetation zonation. The north is characterized
by Euro-Siberian vegetation, comprising deciduous
forest, while in the south there is a transition from
Euro-Siberian to Mediterranean-type vegetation.
The natural deciduous forest below 400 m is
dominated by ash (
Fraxinus excelsior
), lime (
Tilia
sp.), hazel (
Corylus avellana
), maples (
Acer
spp.),
oaks (
Quercus
spp.), poplars (
Populus
spp.) and holm
oak (
Quercus ilex
). However, eucalyptus plantation
(
Eucalyptus globulus
) and improved pasture-land
dominate parts of this coastal zone. Between 400
and 1100 m oaks (
Quercus robur
and
Quercus
petraea
) dominate the southern slopes, with
beech (
Fagus sylvatica
) and holly (
Ilex aquifolium
)
predominant on northern slopes. Native forest
has been highly modified to create pasture land.
From 1100 to 1800 m birch (
Betula
sp.) is
dominant, while above 1800 m the sub-alpine
vegetation comprises shrubs (e.g.
Genista
sp.,
Erica
sp. and
Ulex
sp.) and mountain grasslands. The
Mediterranean influence further south produces a
native vegetation community dominated by holm
oak, with melojo oak (
Quercus pyrenaica
), bay laurel
(
Laurus nobilis
) and strawberry tree (
Arbutus unedo
).
Riparian vegetation up to 700 m altitude is
dominated by groves and galleries of alder (
Alnus
glutinosa
)(Lara
et al.
, 2004). Willow groves formed
by
Salix atrocinerea
(Northern Cantabrian cordillera)
and
S. cantabrica
(Southern Cantabrian cordillera)
replace alder where soils are thin or where
there are large river level fluctuations. At high
altitudes alder is replaced by ash or hazel, while
in steep valleys beech, oak and mixed Atlantic
forest can dominate the riparian forest. Where
natural riparian forests have been modified by
human activity the vegetation is usually dominated
by brambles (
Rubus
spp.), roses (
Rosa
spp.),
hawthorn (
Crataegus monogyna
) and blackthorn
(
Prunus spinosa
). Pasture land has also been created.
Average population density is 103 inhabitants
km
−
2
; towns and cities are concentrated along the
coast, and the main city of Santander has 184 000
inhabitants.
Alder-ash alluvial forest
Alder-ash alluvial forest is one of the most
extensive riparian ecosystems in northern Spain
and classified as a priority habitat (91E0
*
, Annex
I) under the Habitats Directive (Council of the
European Communities, 1992). The habitat
comprises mainly alders, ash and willows
(mainly
Salix alba
). The main phytosociological
associations that describe this habitat in detail
are the
Alno-Padion
,
Alnion incanae
,
Salicion albae
,
Hyperico andrisaemi-Alnetum
and the
Salicetum
angustifolio-albae
(IH-Cantabria, 2010). These
vegetation communities form the first line
of vegetation in deep alluvial soils which are
periodically inundated but well-drained during the
drier months.
Fish communities
In the Cantabrian region fish communities are
based on assemblages of 15 native species. Atlantic
salmon (
Salmo salar
) is one of the most endangered
and characteristic fish in the region (Garcıa de
Le aniz
et al.
, 1992). Salmon fishing occurs in four
of the main river catchments, (the Deva, Nansa,
Pas-Pisue na and As on rivers), but historically in
another eight rivers. These salmonid rivers are
dominated by brown trout (
Salmo trutta
), eel
(
Anguilla anguilla
) and Adour minnow (
Phoxinus
bigerri
); allis shad (
Alosa alosa
), Ebro barbel
(
Luciobarbus graellsii
), madrilla (
Parachondrostoma
miegii
) and sea lamprey (
Petromyzon marinus
)are
only found in the lower parts of some of the
