Paludi di Gonars
The Regional nature biotope Paludi del Corno was instituted in the SCI (LR 42/1996). Within the biotopes there are norms in force that protect the environments and species that are most vulnerable and of higher naturalistic value, they create incentives for activities of environmental restoration, allowing in any case agricultural activities to be maintained.
This SCI represents a part of the most important and vast groups of fresh-water humid areas in the Friuli Venezia Giulia Region, zones that have survived the simplification of the hydro-graphic grid and the drainages that were carried out in the plains of Friuli during the last century. The area, situated at an average height of 15 meters above sea level and at about twenty kilometres from the Adriatic sea, is characterised by the rising to the surface of groundwater tables which, having gone underground along the Southern feet of the Alps and flowing towards the South in deep detrital deposits of fluvioglacial origin, rise to the surface in correspondence with individual springs of rather small size or with vast depressions and flow freely with no regime inside the alkaline fens, before joining the artificial channels that feed the resurgence rivers, which are characterised by a considerable volume of water. The emerging water is very pure and has a nearly constant temperature.
The site is characterised by a complete series of humid habitats, with examples of springs with Cladium mariscus, of natural humid grassland characterised by Molinia caerulea, of alkaline fens characterised by Schoenus nigricans and providing refuge to many micro-thermal species of animals and plants (glacial relicts).
Due to the continuous reduction of these habitats in the plain, the dry grass land, the mesophyte hedges and the strips of land on the river banks with Salix cinerea and Alnus glutinosa are of great importance.
The sites also host some of the rare populations of endemic and steno-endemic species. In particular, the SCI hosts Erucastrum palustre (Pirona) Vis, a species of Community interest. The SCI also hosts Euphrasia marchesettii and Liparis loeselii (annex II, Habitats Directive) and the endemic species Centaurea forojulensis Poldini.
It is also possible to find many other species that are endangered or in any case rare because of the big reduction of humid environments, among which: Allium suaveolens, Cirsium canum, Gentiana pneumonanthe, Hottonia palustris, Orchis palustris, Plantago altissima, Senecio fontanicola, and Sesleria uliginosa.
All the species of flora listed so far are included in the Red Book of Plants of Italy, since they are considered as endangered species, even if with different levels of protection (from threatened to vulnerable to rare), for a total of 11 botanical species.
There are also numerous zoological emergencies in these spring environments, and those belonging to the reptile and amphibian groups are particularly important.
Among reptiles mention should be made of the conspicuous presence of important relict populations of Zootoca vivipara carniolica, a micro-thermal prairie lizard that in these environments represents a glacial relict from the post-Wurmian era. In this area the Vipera aspis francisciredi is still very widespread in various populations that are numerous locally, but
mostly isolated from each other. Elaphe longissima, Coronella austriaca and Natrix tessellata are other reptiles that live on the sites. Coluber viridiflavus is frequent at the margins of the cultivated areas that surround the humid habitats, where it actively preys on Anguis fragilis, Podarcis muralis and Lacerta bilineata (mentioned as Lacerta viridis in the Habitats Directive). In the zone Emys orbicularis, a species of Community interest, is still quite common.
Among the amphibians Rana latastei is particularly widespread, as is Rana dalmatina. In the stagnant waters live Triturus carnifex and Triturus vulgaris meridionalis, together with considerable populations of Bombina variegata and Rana esculenta. Hyla intermedia (cited as Hyla arborea in the Habitats Directive) is widespread in all the environments included in the sites.
From the ornithological point of view the area is interesting due to the presence ofaquatic birds, in particular during the migration period. It should be noted that there is a presence of herons with Ixobrychus minutus (nesting locally), Nycticorax nycticorax, Egretta garzetta. The area hosts places for the reproduction and hibernation of Circus pygargus and Circus cyaneus.
Species such as Lanius collurio, Alcedo atthis, Porzana porzana, Remiz pendulinus have also been sighted.
The distribution of fish is influenced by the particular characteristics of the emerging waters, which are purity, low temperature with modest thermal differences and high oxygen content. This particular situation allows cyprinids and salmonids to live together. Species characteristic of waters that are slow and rich in vegetation can therefore be found, such as Cobitis taenia, and species living in flowing waters such as Cottus gobio.
Among the aquatic invertebrates the presence of the Decapoda crustacean Austropotamobius pallipes fulcisianus should be noted, which is a species of Community interest.
The site is part of the main area remaining from the habitats that characterised the springs of the Region before the great drainages carried out in the Thirties and Fifties. In 1930 the surface of these habitats, between the Tagliamento River and the Isonzo, was estimated to be over 6000 hectares, while the present habitats summed all together do not amount to more than 200 hectares, fractioned into many areas of limited extension.
The SCI (according to a census taken in 2005) hosts 64% of the remaining population of Erucastrum palustre (Pirona) Vis, a species of Community interest. This species, due to the continuous reduction in its number and the areas where they live, is to be considered as in danger of imminent extinction. The SCI also hosts a considerable population of Euphrasia marchesettii (Annex II).
With regard to this and many other species of flora, cited in the previous part, the three sites that are the subjects of this project represent the only places within the Veneto-Po valley plain where the species can be found.
The habitats of the site represent a fundamental area for the survival of different species of amphibians and reptiles, such as Triturus carnifex, Bombina variegata, Rana latastei, Rana lessonae, Rana dalmatina, Hyla intermedia, and Emys orbicularis, which have by now practically disappeared from the more intensely cultivated agricultural areas because of the destruction of humid environments.
On the site there are also extensive populations of the rare Zootoca vivipara carniolica, a subspecies that is present exclusively in the plain. Even though it is not mentioned in the Habitats Directive, the presence of populations of this oviparous lizard in the Po valley is of extraordinary scientific and biogenetic value.
The site represents one of the rare places in the Veneto-Po valley plain where the Vipera aspis francisciredi lives.