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PATRIMONIO MUNDIAL PYRÉNÉES-MONT PERDU

Paisaje: naturaleza y cultura

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«Pirineos-Monte Perdido»

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This will cross-reference all available documents in our data base related to the UNESCO World Heritage Site

Sub-Alpine zone (1,700-2,400 m)

Xerophile pine forest (Pinus sylvestris)

Scots pine is also to be found in the sub-Alpine zone, where it grows at an elevation of between 1,700 and 1,900 m, preferring windy spots exposed to the sun and thriving on generally skeletal soils.

It frequently moves into areas cleared by human hands, burned by forest fires or overexploited for farming.

The shrubby species most commonly found in the undergrowth this type of pine forest include common box (Buxus sempervirens) and common juniper (Juniperus communis). Other species found here include echinospartum (Echinospartum horridum) and bearberry (Arctostaphylos uva-ursi).

Sub-Alpine pine forests (Pinus uncinata- Rhododendron ferrugineum)

Spanish pine forests (Pinus uncinata) grow at the tree line at altitudes of between 1,700 and 2,200 m.

This species of tree is well adapted to the extreme environmental conditions typical of high-mountain environments and particularly to prolonged periods when the ground is covered by snow, severe cold and frosts and strong wind.

Spanish pine forests grow in both shady and sunny areas, although it is less dense in sunnier spots, where dwarf common juniper (Juniperus communis nana) and bearberry (Artostaphillos uva-ursi) are also to be found in the undergrowth.

The species most frequently found alongside Spanish pine are rhododendron (Rhododendron ferrugineum), blueberry (Vaccinium myrtillus) and Sorbus chaemespillus.

The shady parts of the Ordesa, Pineta and Bujaruelo valleys are home to forests of Spanish pine, as are the higher areas exposed to the sun in Añisclo and Escuaín.

In the areas where Spanish pines predominate, birch and willow trees have moved into the channels cut by avalanches and landslides.
Despite the harsh conditions due to the cold and snow, which reduce the vegetative season, the oldest trees are to be found in these areas. On Montaña de Sesa, there is one that is approximately 500 years old (LASAOSA Y ORTEGA, 2003).

Pastures above the forests

Extensive pastures stretch out above the tree line at altitudes of between 1,800 and 2,400 m.

Even though some of the grazing land can be regarded as climax vegetation, most of pastureland lies within the natural territory of the Spanish pine and highland scrub. For centuries, these were cut down and used by humankind as they cleared these areas to give them over to grazing for transhumant livestock. The Goríz pastures, the Montaña de Seso and the sunny areas on the Sierra Custodia and Sierra de las Cutas are examples of these grasslands.

Given that many of the original forests were turned over to pasture, this plant community can be regarded as belonging to an Alpinised sub-Alpine zone. During the long process of transformation from forest to pastureland, the soil was simplified and so it is very difficult for forest to reclaim these areas.

In places where grazing has occurred over long periods of time, certain grasses have been able to spread, such as bearskin fescue (Festuca gautieri), alongside mountain tragacanth (Astragalus sempervirens), Festuca eskia, Festuca paniculada, matgrass (Nardus stricta) and Alpine clover (Trifolium alpinum). These herbaceous communities vary depending on the chemistry of the rocks, the orientation of the mountainside, the presence of moisture in the soil and the pressure from grazing livestock.

Even though gramineous and leguminous plants predominate, there are some shrubs such as juniper in the higher, north-facing areas and box on warmer, sunnier slopes. Echinospartum is also usually present.

In areas where there is less or even no pressure from grazing livestock, woody species of plants have been quick to move in. In shadier and higher areas, where patches of Spanish pine woodland have managed to hold on, these trees have succeeded in advancing into lower elevations and into the edges of the pastureland (as can be seen at Las Travenosas and La Crapera on Las Cutas). Similarly, in places where areas of pastureland at lower altitudes adjoin forests, there has been a continuous spread of box, Rhamnus alpina, junipers, sorbs and roses.