The two oases.
Campagna is a small jewel that rises within a valley with almost unique naturalistic and geological peculiarities, in fact, it is also defined as "the City of the two Protected Areas" and, by insiders, an important tectonic window. The conformation of the valley and of the territory, which extends (south) to the Sele river, is the result of erosive and geological processes which over the millennia have allowed the formation of a territory with very strong altimetric variations; it goes, in fact, from 30 m a.s.l. up to 1,790 m a.s.l. of M.te Polveracchio (third highest peak of M.ti Picentini).
The tectonic window of Campagna was reported for the first time in 1967 by Scandone and Sgrosso, two expert geologists, who, in a note dated 1974, presented in Rome at a scientific symposium, defined it as "one of the most explanatory structures of the tectonic structure of the external units of the Campania-Lucanian Apennines".¹ To better understand the importance of the geology (tectonic window) of the country, it is necessary to trace a rapid excursus on the formation of the continents. Originally our Earth was a mass of fiery rocks which, over time, cooled and formed the surface on which we live: the "earth's crust".
We must imagine our planet as a hard-boiled egg with a broken outer skin representing the crust. Over the course of millions of years, due to the movements of the mantle, which we can compare to the albumen of the egg, these jagged crusts have sunk, raised and collided with each other, creating layers of different geological nature on top of each other, like a sort of multi-layered mixed cake. To study the geological history of an area, geologists use tools that allow to know directly or indirectly the composition of each layer; in this case, facing a tectonic window, it is possible to identify the various layers that make up an area by observing it even with the naked eye.The tectonic window is formed through the progressive erosion of a more recent tectonic unit (single portion of the earth's crust) which, over the course of thousands of years, brings to light an older unit. It was the rivers of Campagna that over the course of thousands of years, helped by tectonic movements, dug the more recent layers and brought out the older ones that gave shape to today's valley. Specifically, the geological structure of the window in question consists of the Monte Croce unit.
It, in turn, is made up of facies which indicate the physical-chemical-biological characteristics of a rock and their difference indicates the geological evolution of a territory. The whole area of the Picentini Mountains is made up of dolomites, dolomitic limestones and limestones which, following the formation of the southern Apennines, overlapped on the original marine sediments. Indeed, in the early days, a large part of the southern Italian area did not exist, in its place there was the seabed which was formed by sediments that today we call the Lagonegrese Unit. From the most recent to the deepest layer, it is divided as follows: Lagonegro I, Lagonegro II and Vallimala.
The Campagnase tectonic window is clearly evident in the images below, where the Carbonate Unit of Mt Polveracchio and Mt Raione, and the Lagonegrese one of Monte Croce are highlighted with different colors and simplifying their structures. It is possible to observe the erosion of the Tenza and Atri Rivers along the edge of Mount Croce and the consequent separation of the two units (image 1 and 2).
Image 3 schematizes the tectonic window of Campagna where it is possible to see in section the unit of Mt. Croce enclosed in the valleys formed by the rivers Tenza and Atri.
It gave the company Farina-Valsecchi & c. the concession of reclamation works and the use of the waters of the Sele, Tusciano and Calore rivers, for the irrigation of the lands to be reclaimed² and for the construction of the Persano dam which has precisely the function of regulating the waters used for irrigation for more efficient use of water resources. In this artificial reservoir, the protected area of Persano was established in 1980 (Photos 5 and 6) (ZPS6), it also falls within the Foce Sele - Tanagro Nature Reserve and is also protected by the Natura 2000 network because it is located along the of bird migration. The European protection standards just mentioned well represent the importance of the site which aims to protect biodiversity and water, the latter used to irrigate the Piana del Sele and therefore which will return to our tables in vegetable and animal form. After having framed the regulatory aspect of the Persano Oasis, the time has come to understand specifically the reason for these high protectionist standards, starting from the endemic flora of the site.
The flora is typically hygrophilous, i.e. made up of species that grow in soils rich in water with a humid climate. The typical biocenosis of the site is made up of a tree layer of willows, poplars and alders which create a continuum with the typical riparian forests (that is, they are found between the ground and the water) made up of ferns, horsetails and water lilies. The latter are particular species, just think that the horsetail is among the oldest plants on Earth and has medicinal properties, while the water lily has a mobile root and is able to absorb nutrients from the water; both are widely used in phytoremediation and therefore are already their guarantee of clean and healthy water. Furthermore, in the Oasis of Persano we find reedbeds, marshes, meadows, coppice woods, Mediterranean scrub, in short, an extremely rich plant biodiversity (photo 7).
The characteristics of the endemic flora allow the survival of the so-called primary and secondary consumers as well as seasonal volatile species. Surely the symbolic animal is the Otter (Lutra lutra), a species considered at risk of extinction, which has found in these waters a suitable place to be able to reproduce and therefore survive; the WWF considers it among the animals to be safeguarded and protected8, both because it is found at the "limit of the scale of rarity" and because "where its populations are not as rare and localized as in Italy, it can be an excellent indicator of quality environment (riparian environments), especially in relation to water quality". Other animal species live protected by these waters and this vegetation: - Mammals: badgers, foxes, wild boars, weasels, skunks; - Migratory birds: herons, egrets, diving ducks, gurnards, coots, water rails; - Birds of prey: sparrowhawks, kestrels, buzzards and falcons. - Aquatic animals: eels, tenches, carps, lampreys, barbels, chubs. In the Persano Oasis it is possible to take advantage of two paths, 1 km long and 400 m long, along which there are observation huts (photo 8) for birdwatching enthusiasts or the simply curious.
The nature trails are various, documented and traced by the CAI in the "Carta dei Sentieri del Parco Regionale dei Monti Picentini" and available to all the municipalities in the area. In the canyon of the inhabited center the Tenza River meets the Atri. Going up along the two river courses, the mountainous area begins on which the various vegetation passages are visible, influenced by the ever-increasing altitude. At the beginning of the ascent there are holm oaks, chestnuts and Turkey oaks, going up alders, elms, lilies, maples appear up to the highest point with the presence of the beech that covers Mount Polveracchio. The latter with its 1790 m a.s.l. it is the third peak of the regional district. Its name could derive from the characteristic top devoid of vegetation which, when it is whipped by the winds and covered with snow, seems to be covered with dust. Mt. Polveracchio, whose summit marks the border with the municipality of Acerno, has been identified as a Site of Community Importance by the Natura 2000 Network.
But what is so special about this site? Its symbol is the wolf (Canis lupus), so this suggests that the main feature of the area is the presence of this animal. For the record, the wolf is a very mobile animal, during the night it can travel several km, therefore it is difficult to find a permanent population on Mount Polveracchio, but certainly the wolf (or rather wolves since they live in packs) adopts the Regional Park as a hunting area. The importance of the wolf is high, in fact it has been protected since the 1970s with safeguard measures that prevent its disappearance. Thanks to its inclusion in the Red List16 as a vulnerable species, today it is returning to repopulate areas where it had disappeared. Protected areas, such as those of Polveracchio, allow this species to repopulate our woods. Wolves also help us out with a wild animal that has been causing a lot of damage for several years: the wild boar. The wolf is not the only mammal present in the Polveracchio area, there are also the dormouse, the dormouse, the dormouse, the marten, the badger and the wild cat. There are also significant species of amphibians such as: the yellow-bellied toad, the Apennine fire salamander and the Italian newt. Among the nocturnal and diurnal birds of prey there are: the peregrine falcon, the buzzard, the owl, the owl, the owl, the barn owl and the black woodpecker. In short, just considering the fauna present, the protection of the area is justified. The Polveracchio area also has another specificity linked, this time, to its vegetation. A very particular beech forest persists on the Polveracchio, deriving from that of north-eastern Europe. To better understand the importance and the "journey" of these plants we need to start from the last glaciation called Wurm, which occurred between 20,000 and 10,000 years ago: northern Europe was covered by ice, central Europe by tundra and steppes, and forests migrated to warmer areas (Figure 10). With the end of the glaciation, the European structure returned to today's one, but some plant species found, in southern Italy, areas with pedoclimatic characteristics (i.e. of the soil and climate) suitable for being able to remain there.
Precisely for this reason today there is beech in Italy, otherwise it would be a typically central European species. So are all the beech trees in Italy of glacial origin? Yes, but the particularity of the beech tree found on Polveracchio is due to its Himalayan-Caucasian origin. The beech has "walked" a long way to come to us and has never moved, becoming prized for its "pre-glacial relict value". This plant is a species that, even in southern Italy, is mostly found in inland areas, while on the Polveracchio it can be defined as coastal because it "overlooks" the sea (Photo 11). The hot-humid coastal air, coming from the South, is mitigated by the cool air from the North, this creates a favorable humidity condition for the plant and for the inhabitants of the area themselves, in fact 5 rivers¹8 are born on the Polveracchio thanks to the rainfall that forms from the meeting of these two opposing air currents and from the geological composition. In short, by combining the specific vegetation and fauna of the area, it is easy to understand the attention at the community level of the site which has been classified A1 - Areas of significant naturalistic interest. In fact, it is only in this way that the population of the tall relict beech and of the other plant species present can be perpetrated, as well as protecting the fauna and, in general, the extreme biodiversity of the area. The territory of Campagna has many naturalistic peculiarities, I hope I have described them all in a simple and clear way; I hope to have established in the reader a greater curiosity and critical sense towards our territory.
I thank the Città di Campagna ETS association for the opportunity it gave me to be able to contribute, in my small way, to describing what I love most about my country.
Text by Dr. Antonello D'Ambrosio.
1. THE GEOLOGICAL SOCIETY OF AMERICA. GEOLOGIC TIME SCALE. (2009).
2. Storia del Consorzio Destra Sele (http://www.bonificadestrasele.it/la-storia/)