Le Tre Venezie on-line - AREE NATURALI PROTETTE Friuli Venezia Giulia

he nature Reserve covers an area of 510 hectares on the extreme south-west border of the Carnia pre-alps and is surrounded by a splendid landscape. Its severe rock faces and its screes act as a backdrop to the wide bed of the Tagliamento river.
Besides the mountains and the river, the Reserve also boasts a crystal-clear lake rich in flora and fauna, encouraged by its mild climate. In this specific area, the Tagliamento river is over a kilometre wide. The karst morphology appears severe and wild, with evident contrasts in the landscape. The Mount Prat plateau stretches out on top of the rocky slopes, and it is interspersed with woodland, meadows and grazing lands that overlook the Arzino valley to the west. Lake Cornino lies in a vast hollow carved out by landslides which occurred after the retreat of the glacier. The Lake is 8,500 square metres wide and 8 metres deep, it has a green-azure colour and is fed by subterranean karst currents.
The rock faces of the area are made up of layers of limestone, which contain many fossils. Common among theses are the fingerprint-shaped ellispactine organisms which were responsible for the formation of the coral-type reefs. There are also fossils of other species such as seaweeds, sea urchins and small shellfish. The fragments breaking away from the rocky surfaces surrounding the plateau, have formed wide scree-covered areas over the centuries: this is due to strike faults that have created strips which are more easily subject to erosion. The Tagliamento river is considered to be the “king of alpine rivers”. It is the only river with a primarily natural bed and therefore of great interest from the nature viewpoint. Research on its morphology and vegetation is also carried out here. The Reserve includes an area measuring about 6 kilometres in length, which is the only section out of the 170 km-long river to be part of a protected area. The river bed separates the Reserve from the Osoppo plain, which is surrounded by the Carnia and Julian pre-alps. The plain was formed by huge glaciers during the glacial period, roughly between 75 and 10 thousand years ago. As these moved down from the Alps, they deeply eroded the ground and the edges of this area by forming ridges of debris resulting in the creation of the morainic Amphitheatre of the Tagliamento river. As the glaciers retreated, such ridges acted as natural barriers which dammed up the Tagliamento river resulting in the formation of a huge lake. The lake stretched northwards up to Venzone and Somplago from which some islands emerged and later formed the Osoppo hills.
Much later, the Tagliamento river carried huge quantities of alluvial soil down into the lake. Now, only the Cavazzo Lake and a huge water table, which is one of the most important water resources of the region, remain. Traces of glaciers are evident in the Reserve and as can be seen by the moraine on the Mount Prat plateau, which was formed by masses of rock carried down from the Carnic chain of mountains, and by its sheer rock walls.
The differences in landscape are characterised by the different species of vegetation. Flora typical of alpine areas cohabits with that usually found in hot, dry, Mediterranean climates and with South-European and Illyric-Balcanic species.
The orientation of the rocky slopes and the reflection of the sun on the river bed have an insulation effect, which results in a particularly mild climate for the thermophiles which are usually found along the coast or in southern regions. Particularly surprising is the presence of holm oaks (Quercus ilex) in the rocky areas, whose lush green is specially vivid during winter and contrasts with the thermophilous woodland scattered across the slopes.
The vegetation of the Tagliamento river is sparse and discontinuous, it is characterized by pioneer or unstable species living on the gravel of the bed, which are rare or endemic to this environment. The fauna includes many species, which are typical of different habitats including the mountains, the plains and the marshes, but it is particularly interesting for the bird species found in the area. Lakes and ponds are favourable places for herons, little ringed plovers, ducks and gulls, while the barren and steppe-like river beds host the woodlark (Lullula arborea) and the goatsucker (Caprimulgus europaeus). The woodland hosts many thermophile species such as the white Western Bonelli Warbler (Phylloscopus bonelli) and the rock bunting (Emberiza cia). However, the rocky areas are the most interesting ones as they house colonies of rock-birds such as the raven (Corvus corax) and the crag martin (Ptyonoprogne rupestris). For some rare and precious species such as the peregrine (Falco peregrinus), the eagle-owl (Bubo bubo) and the black kite (Milvus migrans) this is the best nesting site in the region.
It is also particularly important for its birds of prey and is one of the most interesting Alpine areas for bird watching. During the eighties, the griffon (Gyps fulvus) was successfully re-introduced in the Reserve. It is a kind of vulture with a wingspan of nearly 3 metres and 8-12 kg in weight. Many examples have started to nest on the nearby rocky slopes and have formed a colony which today boasts somewhere between 60 and 100 griffons spread over the Eastern Alps. This colony attracts those griffons coming from other European areas, in particular those arriving from Croatia during the summer season.