The ecoregions of Andorra are enumerated in a single ecoregion: Pyrenees conifer and mixed forests. In Andorra, this ecoregion is severely fragmented, with the major axis of urban development being the Riu Valira River, including its two tributary forks. This intense development is where virtually all the 85,000 human population lies, and the development prevents any meaningful biological corridor connecting the upper slopes on either side of the river valleys.

Pyrenees conifer and mixed forests (in dull yellow overlay). Source:WWF

Geology

The geology of the ecoregion is dominated by that of the Pyrenees Mountains themselves. The central axis of the Pyrenees is comprised of granite and slate exceeding 200,000,000 million years in age, flanked by Mesozoic (limestone, dolomite, and sandstone) and quaternary sedimentary rocks. Alpine orogeny here has shaped the complex Pyrenean landform, that consists of steep rocky slopes, spectacular canyons, high karstic plains and  summits in the entirety of the Pyrenees exceeding 3000 metres. Evidence of Quaternary glaciation is abundant, with spectacular cirqueAn amphitheatre-shaped valley head, formed by glacial erosion and ice-smoothed, U-shaped valleys, and a few small glaciers are found on some of the highest Pyraean peaks.

Vegetation of the Pyrenees conifer and mixed forests

The Pyrenees Mountains are an interzonal mountain system (termed orobiome), essentially a transition area between Central and Mediterranean Europe. There remains a high degree of [intact habitat] over large areas, especially at higher elevations. Approximately 3500 vascular plant species are recorded in the Pyrenees conifer and mixed forests, of which around 200 are endemic, such as Thalictrum macrocarpum, Androsace hirtella, Saxifraga hariotii, Hieracium compositum, Gentiana burseri, Globularia gracilis and Galium caespitosum. There are two endemic genera representing relicts of subtropical origin: Borderea pyrenaica and B. chouardii from the central Pyrenees, and Xatardia scabra from the eastern Pyrenees. The genus Ramonda, which has one species endemic to the Pyrenees (R. myconae) and two species endemic to the Dinaric Mountains, is also noteworthy.

Birds of the Pyrenees conifer and mixed forests

Lammergeier (Gypaetus barbatus). Source: Richard Bartz Around 120 species of breeding birds have been recorded in the Pyreness conifer and mixed forests, along with about the same number of migratory species. The highly endangered raptor, lammergeier (Gypaetus barbatus), is reisdent in this ecoregion, of which some forty pairs are  found in the Pyrenees Mountains. Other endangered species, more widely distributed in Northern Europe, form disjunct populations in certain montane areas. These taxa include the capercaillie (Tetrao urogallus) and the ptarmigan (Lagopus muta).

Mammals of the Pyrenees conifer and mixed forests

Around sixty-four mammalian species are found in the Pyrenees Mountains, including some endemic subspecies. Large carnivore populations have been reduced in size or fragmented into small remaining groups. The brown bear (Ursus arctos) population is composed of only a few individuals. Large herbivores are generally have wide distributions, with the exception of the Pyrenean endemic ibex subspecies (Capra pyrenaica pyrenaica), which became extinct in early 2000.

Conservation

The ecoregion is threatened by ongoing urban development as well as certain logging uses; however much of the damage of habitat fragmentation has already been carried out by the virtual cutting ot the two sides of the forested valleys by a swath of roadway, commercial and residential development. The most significant mitigation measure would be to provide for a significantly wide biological corridor to connect the two valley sides. Given the extent of urban development, such an action would likely be expensive and entail a tunnel for the main through roadway and a restored habitat above the tunnel to connect the two valley sides.

References

• Elena-Rosselló, R. 1997. Clasificación Biogeclimática de España Peninsular y Balear. Ministerio de Agricultura, Pesca y Alimentación, Madrid.
• Gomez Campo, C. 1985. Plant Conservation in the Mediterranean Ecosystems. Junk Ed. (Geobotanica 7).
• Gruber, M. 1980. Etages et séries de végétation de la chaine pyrénéenne. Ecologia Mediterranea 5.
• Heath, M.F. and Evans, M.I., editors. 2000. Important Bird Areas in Europe: Priority sites for conservation. Vol 2: Southern Europe. BirdLife International (BirdLife Conservation Series No: 8). ISBN: 0946888361
• IUCN. 1996. 1996 IUCN Red List of Threatened Animals. IUCN, Publication Service Unit, Cambridge. ISBN: 2831703352
• Medail, F. and Quezel, P. 1997. Hotspots Analysis for Conservation of Plant Biodiversity in the Mediterranean Basin. Ann. Missouri Gard. 84
• Ozenda P. 1994. Vegetation du continent Europeen. Delachaux et Niestle, Lausanne, Swizerland. ISBN: 2603009540
• Shackleton, D.M., editor, and the IUCN/SSC Caprinae Specialist Group. 1997. Wild Sheep and their Relatives. Status Survey and Conservation Action Plan for Caprinae. IUCN, Gland, Switzerland and Cambridge, UK. ISBN: 2831703530
• Sainz Ollero, H. and J.E. Hernández-Bermejo. 1981. Síntesis corológica de las dicotiledoneas endémicas de la Pen´nsula Ibérica e Islas Baleares. INIA, Madrid.
• Swenson, J.E. et al. 1999. Final Draft Action Plan for Conservation of the Brown Bear (Ursus arctos) in Europe. WWF, Switzerland.
• Water, K.S., and Gillett, H.J., editors. 1998. 1997 IUCN Red List of Threatened Plants. Compiled by WCMC. IUCN, Publication Service Unit, Cambridge.
• WWF and IUCN. 1994. Centres of Plant Diversity. A guide and strategy for their conservation. 3 Volumes. IUCN Publication Service Unit, Cambridge. ISBN: 2831701988