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Nature
Nature, biodiversity and balance
The Sierra de Guara is not just a backdrop for riding. It is a living, protected, and extraordinary territory, where every pedal stroke takes you through unique habitats, unrepeatable geological formations, and a biodiversity that places this corner of the Aragonese Pre-Pyrenees among the most valuable natural spaces in southern Europe.
Protected nature
The Sierra y Cañones de Guara Natural Park, declared in 1990, is the largest protected natural area in Aragon, with 47,453 hectares plus an additional 33,286 ha of Peripheral Protection Zone. This area far exceeds other Aragonese landmarks such as Ordesa y Monte Perdido or Posets-Maladeta. All general information, interpretation centers, and park management tools can be found at Sierra y Cañones de Guara Natural Park. Government of Aragon (aragon.es)
Guara is located on the southern edge of the Pyrenees, in the Pre-Pyrenean ranges of Alto Aragón, in the center of the province of Huesca, spanning four regions: Alto Gállego, Sobrarbe, Hoya de Huesca, and Somontano de Barbastro.
Its membership in the Natura 2000 Network grants it a double European protection status: Special Protection Area for Birds (SPA) and Site of Community Importance (SCI), recently converted into a Special Area of Conservation (SAC) following the approval of its management plans in 2021. https://www.aragon.es/-/red-natura-2000
Added to these recognitions is the Sobrarbe-Pirineos Geopark, a UNESCO designation that recognizes the extraordinary geological heritage of the Guara sector located in the southern reaches of Sobrarbe. geoparquepirineos.com
Mountain ranges, canyons, and mallos
The Park takes its name from the Guara mountain range, which runs about 15 km west-east between the Guatizalema and Alcanadre rivers, with the Tozal de Guara (2,077 m) as its highest peak. The Gabardiella, Arangol, Balcez, and Sebil ranges, between 1,500 and 1,600 m, complete the Park’s landscape.
The massif is primarily limestone: marine-origin limestones folded 65 million years ago and shaped by karst processes, and at its feet, the giant accumulations of conglomerates from which the mallos have been sculpted—that characteristic wall defending the south of the range in the transition toward Hoya de Huesca and Somontano. The mallos of Salto de Roldán, San Martín de la Bal d’Onsera, Vadiello, or the Gorges between Colungo and Asque are essential landmarks for any cyclist riding in the area. More on rock formations at https://www.prepyr365.com/en/rutas/naturaleza/geologicas-y-paisajisticas.html
The undisputed protagonist of this landscape is fluvial erosion. The rivers and ravines of Guara pierce the limestone and conglomerate reliefs, creating the deep canyons that have brought international fame to the range. Among the best known in the world of canyoning and MTB are:
- Flumen River: Palomeras, at the foot of Salto de Roldán, and its tributary San Martín de la Bal d’Onsera.
- Guatizalema River: Palomar narrows and tributaries such as Lazas, San Chinés, and Isarre.
- Formiga River: upper section and the extremely narrow Gorgonchón.
- Alcanadre River: Gorgas Negras, Barrasil, and Peoneras, with the Mascún and its tributaries (Raisén, Otín, La Virgen…)
- Isuala de Balcez River: upper section, Oscuros and Estrechos, and tributaries such as Alborzeral and Cautiecho.
- Vero River: linked gorges from Los Oscuros to Villacantal and the Fornocal tributary.
The water quality of Guara’s rivers is listed in the Inventory of Fluvial Points of Interest. The Isuala de Balcez River, from its source to its mouth at the Alcanadre, is classified as a Fluvial Nature Reserve. https://www.miteco.gob.es/…
Flora and fauna of Guara. Exclusivity and environmental frontier
Guara’s position on the climatic border between the humid north and the dry south has created a marked difference between the north and south slopes of the range, and with it an extraordinary variety of flora and fauna species, some at the southern limit of their Pyrenean distribution.
13.2% of the Park’s surface features high mountain alpine environments, with specimens of mountain pine, beech, and fir trees in the southernmost location of the Pyrenees. Corsican pine and Scots pine forests coexist with boxwood in the shaded areas of the range. But the most common forests are of Mediterranean affiliation: Portuguese oaks and holm oaks that covered much of the mountains until the mid-19th century. Magnificent specimens of those oaks survive in San Úrbez de Nocito, Otín, and Bagüeste. Among the holm oaks, the thousand-year-old holm oak of Lecina stands out, listed in the Inventory of Singular Trees and chosen as European Tree of the Year 2021. More information on singular trees at http://radiquero.com/arboles/
On the rocky cliffs of mallos and canyons grow highly specialized plants like the king’s crown and bear’s ear, and species exclusive to the range like Petrocoptis guarensis, which adorns the limestone walls of the Alcanadre and Vero canyons with its pink flowers. 50% of the Park’s surface is occupied by scrubland dominated by hedgehog broom, which tints the Park yellow in June. More on flora and biodiversity at https://www.prepyr365.com/en/rutas/naturaleza/geobotanicas.html and at https://www.prepyr365.com/en/rutas/naturaleza/botanicas.html
Regarding fauna, the MTB trails of Guara offer inevitable encounters with wildlife. Among the mammals, wild boar, roe deer, feral goats, foxes, beech martens, wildcats, badgers, and otters in the clean river waters stand out. The caves and chasms house several species of threatened bats.
The rivers are home to the red-tailed barbel, trout, bermejuela, and the endangered native crayfish, as well as the Pyrenean brook salamander, an amphibian exclusive to the Pyrenees that reaches its southern distribution limit here. Among the most valuable invertebrates are the Rosalia longicorn, the stag beetle, the great capricorn beetle, and the butterfly Erebia lefebvrei abosi, discovered in 2017 and exclusive to Guara.
