Noah's Ark

Seashore plants growing thirty kilometres inland, firs more southern than their neighbours, four truffle genotypes out of the seven in Europe. The Sangro valley is a refuge.

The Sangro valley is a biogeographical threshold: on one side the Mediterranean region, on the other the Euro-Siberian one. It is a frontier, and like all frontiers it gathers things that elsewhere do not belong together.

The sea that is no longer there

On the scaly clays grow halophytes — plants adapted to salt — that are normally found on the seashore. How did they get so far inland? They are ancient forms of vegetation, going back six million years to the drying out of the Mare Nostrum: that event helped spread plants suited to the salt soils of the east. Later, with tectonic and climatic change, these plants were left stranded — some by the sea, others on the clay soils of the interior.

A glacial refuge

During the cold periods of the Quaternary — in particular the Würm, which ended about fifteen thousand years ago — the valley acted as a refuge. Holly, bay laurel, Griolet's sedge, the juniper woods and the holm-oak woods that live alongside the silver fir around Borrello and Rosello are all evidence of this.

And this is where the story becomes precise: the silver fir of Borrello and Rosello shows close genetic ties with those of southern Italy, while the firs just beyond the Sangro — on the Gran Sasso, on the Monti della Laga — have more in common with those of the Alps. The river separates two different evolutionary histories.

Four out of seven

Confirmation comes from underground. Truffles live in mycorrhizal symbiosis with forest trees, and in Europe seven genotypes are counted: four of them have been identified in the middle Sangro, between Quadri, Borrello, Rosello, Pizzoferrato, Gamberale and Montenerodomo. Such concentrated genetic diversity suggests that this area worked as an ark: during the last glaciation, land bridges formed where animals and plants built up colonies, from which they later spread back across the continent.

Three hundred hectares built by mistake

A little further down, where the Sangro and the Aventino meet, there is a case of the opposite kind: a dam built for the industrial needs of the valley and for irrigation. Within a short time the lake turned into a marsh of bulrushes, rushes and club-rushes. A WWF oasis in 1987, a Regional Nature Reserve in 1990: some seventy species nest here today and more than two hundred have been recorded, among them the great white egret, the spoonbill, the black stork, the osprey and the flamingo.

In short: a place where species of Mediterranean, European and Asian origin come together. That is why people speak of Abruzzo as the “Green Region of Europe” — and why, here, the phrase is not a slogan.