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Gorbeia Natural Park
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Characteristics of the physical and biologic environment
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- Climate
 La altitud del The altitude of Gorbeia Natural Park confers it a typical mountain climate. It acts like a great barrier that stops the wet winds that proceed from the Bay of Biscay, and brings about the important differences that exist between the northern slopes, which are more humid, and the southern slopes that are drier and sunnier.
Rainfall is abundant, throughout the year, although autumn and winter are the Rainier's seasons. In general terms, rainfall is over 1300 mm per year on the northern slopes, reaching up to 2000 mm on mountaintops. On the southern slopes rainfall decreases to approximately 1000 mm per year.
Annual average temperature varies between 12ºC centigrade in the valleys in Biskaia and 8ºC in higher levels. Here, rainfall is in the form of snow during the winter months and this snow lasts until early spring.
- Mineral wealth
Rocks are sedimentary, with abundant sandstones, marls, lutites and limestones. Flinty escarpments form rounded mountaintops like those of Gorbeiagane, Berretín or Oderiaga. On the other hand, limestones form rough and pronounced escarpments, with a predominance of nearly vertical cliffs like those of Itxina, Aldamin or Lakanda. These limestones have a high degree of fracturation and karstification, which makes them very interesting aquifers.
- Hydrology
 Gorbeia is the source of many rivers that, apart from having a considerable naturalistic importance since they sustain greatly valuable ecosystems, supplier water to the surrounding villages by means of small water catchments. They then flow towards the big reservoirs that are part of the water supply system for Vitoria and Bilbao.
The Park can be divided into five big valleys: Altube, Arratia, Baias, Zubialde and Undebe. The car stick zone occupies an important part of the surface (around 15%), their form underground circulation is very important. Streams in Gorbeia all have small magnitudes in terms of length and flow, with the exception of the Altube and Baias rivers in which a slight lowering of the water level may be observed during the late summer
- Vegetation and Flora
Beech groves are currently the most extended natural forests. They spread up to and over the 500-700 metre level, with important extensions in Altube, Larreakorta, Itxina and Padrobaso.
Pyrenean oak or Quercus pyrenaica forests are the second type of natural forests in terms of surface. They spread preferably on southern slopes, on dry, sandy and loose soils, in the area of the Baias river and north of Murua.
Sessile oaks, Quercus petraea, are to be found in very steep flinty ravines. It is most extended in La Txara, as part of an Integral Reservation, and in the Padrobasso ravine.
Pedunculate oaks, Quercus robur, occupy the wetter and more clay-ridden soils in lower levels, currently forming small, somewhat degraded groves. This species is mostly extended in Altube (integral Reservation) and in Arbaiza.
Other communities like alder, gall oak, Cantabrian holm oak, pine and birch groves, peatlands, wetlands and crest flora or have a small but very interesting presence.
The destruction of forests has brought about the open spaces, dominated by heather and gorse patches in flinty zones, whereas limestone in deep soils is usually covered with mountain grazing pastures. However, coniferous plantations are the most extended man-made formation.
| Current vegetation |
Surface(ha) |
| Beech |
5862
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| Oak |
998
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| Pyrenean oak |
2105
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| Sessile oak |
288
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| Gall oak |
24
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| Holm Oak |
80
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| Riverside forest |
54
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| Coniferous |
5278
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| Praries and pastures |
1338
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| Bush |
3576
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| Others |
413
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Although situated in the Euro-Siberian region, the territory of Gorbeia Natural Park is the first barrier for the meridional penetration of many elements of the circumboreal and Euro Siberian corology. On the other hand, there are still some Mediterranean relictic elements visible. This brings about a very special wealth in terms of flora, which is increased by the presence of Cantabrian-Pyrenean mountain elements and certain adventitious species.
 As a sample of the specialisation of vascular plants present in Gorbeia, let us state that 23 of them are extremely rare in the Basque Country, of these, three a are only to be found, within Basque territory, in this Natural Park.
The diversity of limestone and flinty substrata, the considerable humidity and the high altitude, all bring about a considerable wealth in terms of mosses and lichens. The catalogue of known briophites has over 290 species in Gorbeia, of which 26 are to be found only in this Natural Park within the Basque Country. Some of them are only to be found here within the whole of the Iberian Peninsula.
- Fauna
Gorbeia Natural Park has around 167 species of vertebrates. This is basically a Euro Siberian, and to a lesser extent, Mediterranean set of animals, the main diversifying factors of which are the series of mountain fauna elements that occupy the massif highlands and a series of species connected to rocky grounds.
Among these there are several species that have been catalogued as threatened species in the Basque Country , especially the otter, a species in danger of extinction that needs clean waters and well-kept riverside forests for survival. The good state of the alder groves in the higher Baias, Zubialde and Arratia rivers have favoured the survival of otters, as that of other species as interesting as the Pyrenean desman, the grey wagtail, or the dipper.
Without doubt, the emblematic species of Gorbeia is the deer, which had disappeared and was reintroduced a few decades ago and is now completely naturalised and in a state of expansion. In mid-September, males fight fiercely for the possession of the harems of females; this is the mating season and the bellowing of males can be heard in the evenings throughout the Park.
The main areas of interest in terms of fauna are: the broad-leafed forests and wetlands in Altube and Lamioji, the meridional rivers and ravines, reservoirs, prairies and open spaces on the southern slopes, the Karstic zone of Itxina - Aldamin - Arraba and the peatland in Saldropo.
- Landscape
The Gorbeia massif is a first-class topographic accident that constitutes a point of reference in the landscape for most of Alava and Bizkaia.
 The great mountain tops on sandstones of Nafakorta, Oderiaga, Gorbeiagane and Berretin, with scant open-field bush or pasture vegetation are situated in the centre of the massif. Among them, with sufficient altitude to dominate all of the mountain tops that surround it, is Gorbeiagane or La Cruz, a very attractive zone with a considerable mountain-climbing tradition due to the ample panoramas that it offers and that has inspired the Natural Park anagram.
An element of considerable visual appeal in the landscape is the Itxina massif, a zone of limestone rock, limited by nearly vertical cliffs, on which there has been spectacular Karstification processes. In its northern limits, there are a series of isolated monoliths known as Las Atxas. Apart from the rocky grounds, there are natural mountain prairies with beech groves and hurdlings of sheep in this limestone zone of the Park. Aldamin rock (1378 metres) is due south east of this point.
The slopes that go down from the mountaintops to the valleys are extremely steep. The most usual vegetation is constituted by broadleaf forests in the Alava side and coniferous plantations with small patches of natural forest in the Biskaia side. Especially noteworthy because of its considerable extension (some 20 km2) and formidable state of conservation is the Altube beech forest, situated in the southeastern end of the massif through which the Altube river and its tributary, the Oyardo river, flow down to a breathtaking waterfall.
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