The Park includes three different mountain groups: the majestic calcareous-dolomitic Gran Sasso mountain chain – with the highest apennine summit, the Corno Grande (2,912 m), where the southernmost glacier in Europe is situated, namely the Calderone – the Laga Mountains, situated in the Park’s northern sector, that reach high altitudes with the Mount Gorzano (2,458 meters) and represent the highest and widest mountain group consisting of sandstone and marlstone in the Apennines; northeast of the Park the calcareous Monti Gemelli (meaning Twin Mountains) are characterized by complex karst phenomena.
Situated in the central Italy the Park includes two different biogeographical regions: the Euro-Siberian and the Mediterranean. This particular location, together with the lithological diversity of the mountain and the high altitude, makes this protected area a territory having a high biological value. In fact, about 2,300 superior plant species, that is more than one third of Italy’s floristic heritage, live in the Park. As far as the animal species are concerned, amphibians represent an emblematic case: fourteen amphibian species are actually present, among which four species of newt have been also counted, which is a unique case in Italy. Furthermore, the Park’s mountains function as a real biogeographical border between the North and the South of the Country: some Mediterranean species reach the northern limit of distribution, while others, especially plants and animals of arctic-alpine origin, reach the southern limit. The most typical environments of the Park consists of high altitudes, where most of the endemic plant and animal species can be found. Furthermore, the so called “glacial relicts” can be found in the highest altitudes, and theyr are represented by plants, insects and vertebrates as well, such as the meadow viper, the European snow vole, the common frog and the alpine newt. On the high-altitude areas there are well-adapted bird species, such as the Alpine chough and the red-billed chough, the Alpine accentor, the wallcreeper, the white-winged snowfinch, the water pipit, the rock partridge, with the peninsular populations being more sizable.
The noteworthy biological diversity of the Park can be also observed in the forests covering about half of the territory with several forest typologies, such as holm oaks, oaks, turkey oaks, manna ashes and hop hornbeams, aspens, chestnut trees and beech trees.
The latter makes up the widest forest formations in which also the relict phytocoenoses can be found, such as the silver firs mainly situated on the Laga Mountains, the formations consisting of holly and yew and some birch stations.
Vast are also the grazing areas, both the primary and the secondary ones: on the Park’s southern side the herbaceous formations turn into real steppes, also due to the particular microclimate conditions. These formations are characterized by a marked eastern element both in the animal and plant community, among which also some endemic species have been observed. In these environments gather many bird species that are diminishing in their European areas, such as the European nightjar, the greater short-toed lark, the ortolan, the crested lark.
We cannot forget the large animals living in the Park, especially those being of great natural interest. One of them is the Apennine chamois, which was reintroduced in 1992 and is present today with more than one hundred specimens on the Gran Sasso mountains; the Apennine wolf, with more than thirty specimens, that has come back to prey on deers and roe deers, whose populations are increasingly growing. Recently, also the Marsican brown bear has been seen again, which shows the strong commitment of the Park Authority in the safeguard and enhancement of an extraordinary and unique territory. The extent of the Park, the variety of its ecosystems, the wide woody surfaces and the proximity with other protected areas make the Park the ideal territory for the conservation of the large animals including species of remarkable natural value. Among these species there is the Apennine chamois, which was reintroduced in 1992 and today more than two hundred specimens live in the Park; and the Apennine wolf, with a population of more than forty specimens, which has started again to feed on its favorite prey: the wild boar. The deer is the subject of a reintroduction program to improve the functionality of the forest ecosystems of the Park, where also the Marsican brown bear appears sometimes. (fonte http://www.gransassolagapark.it)