The area covered by the comune of Tolfa, (some 162 km?) is situated between sea and hills, at an altitude that ranges from 4 to 562 masl. It forms part of a larger geographical area of some 4,500 km? of the Apennine foothills of Lazio situated in the province of Rome . It is known as “Monti della Tolfa” (The Tolfa Mountains).

The area is of enormous naturalistic importance due to its particular geographic position in the centre of the peninsular, where continental and Mediterranean climates meet, and also due to the collective ownership and management of the land, and to the laws that govern its civic uses and apply in most of the area. The Tolfa Agricultural University , a public management body, owns about 70 km? of the land. (“University” is used here in its sense of a group of people – farmers in this case – forming a corporative body). 

Geologically, the area has a somewhat complex structure and is geomorphically undulating and contorted, even though it is at relatively low altitude. Alongside a base of sedimentary rock there are important local manifestations of volcanic activity emanating from nearby volcanic systems, such as the Sabatino Volcano. Dome-like structures of trachyte, a volcanic rock, are very characteristic of the area and provide the local stone that has always been used as building material. 

The climate is of the humid Mediterranean type, but with temperate zones too. It tends to be very changeable and there are important microclimates. This has favoured biodiversity and the presence of abundant and varied fauna and flora. There is an exceptional richness of mammals that includes: wild boar, foxes, porcupines, badgers, stone martens, weasels, pine martens, and many other smaller mammals. Bird life is equally rich, especially with regard to birds of prey. These include: red kites, black kites, kestrels, sparrow hawks, and honey buzzards, while in 2003, a pair of peregrine falcons nested in a disused quarry. There is also a strong presence of reptiles and amphibians, and many different orders of insects. The richness of the fauna and flora is doubtless due in large part to the local cultural practice of extensive – rather than an intensive – land management.   

The forms of flora are generally characteristic of the Lazio region, but they are not found so close together anywhere else, because only here is there such a complex and varied range of meteorological conditions. A visitor can forget the broad vegetation patterns typical of central Europe, the Po Valley, or the Mediterranean and see here how a mosaic of microclimates has produced varied flora that more or less interweave and overlap.   

Two features are particularly noteworthy:

1) The mingling of Mediterranean , continental European, and Balkan vegetation;

2) A great concentration of species of the Carduus genera (thistle families), thorny plants, and thermophile (heat-loving) plants, the rarest in Central Italy .

It is also noteworthy that there are beech trees between 250 and 500 masl, which is much lower than their normal habitat in the Mediterranean region, maples that are relicts of the forest of Central Europe , and other maple species of Balkan origin. The humid areas are home to another taxonomic relict, a tree-like fern, the rare Osmunda regalis, a flowering fern and the largest found in Italy .

The locations of the different types of vegetation are opposite to the normal: the Mediterranean scrub climbs high on the hills where it is sunny and hot whereas the continental types of trees and vegetation are in the bottom of the valleys made fresh by sea breezes, and where there are also large numbers of strawberry trees (Arbutus unedo).

The presence of such varied vegetation is a living testimony of how physical factors affect the biological world. Perhaps in the Mediterranean region there is no other study site that can equal these hills for their meteorological and microclimatic variations and their resulting biological riches.