Montsec's origins are carved upon its contours and preserved within its essence. Two hundred million years ago, the Montsec Mountain Range was a sea basin. The passage of time and the forces of nature have pushed, folded and raised sediments and formed its current appearance. At 1,676 meters above sea level, Montsec is the living heritage of a land where the passage of time and history are told at every step.

FLORA AND VEGETATION

The predominant landscape is Mediterranean, with sub-Mediterranean ubacs, and, to a very localised extent, Euro-Siberian.

The holm oak (Quercetum rotundifoliae) and, on a more restricted basis, the typical coastal oak (Quercetum ilicis galloprovinciale) occupy a large part of the territory. From the ubacs, the following species are worthy of a mention: Valencian oak groves(Violo-Quercetum fagineae), the Downy oak (Buxo-Quercetum pubescentis), groves of lime trees, maples, service trees (Sorbus domestica) and, in particular, the beech groves (Buxo-Fagetum) accompanied by a set of Central European plants, whose southernmost limit in the Pre-Pyrenees can be found on this particular mountain range.

Among the communities that grow in special locations, we should mention the Oromediterranean communities that grow on mountain ridges (Ononidetalia striatae) and the rupicolous communities that grow on cliffs and walls of rock (Asplenietea rupestria), where several endemic plants shelter, such as: Petrocoptis montsicciana, Aquilegia montsicciana, Brassica repanda ssp. turbonensis var. montsicciana, Centaurea emigrantis, etc.

Other plant communities that are unique to the area include: Teucrio-Thymetum fontqueri, Vicio-Geranietum sanguinei.

In terms of lower plants, there is notable mycological interest in some areas of the Montsec.

WILDLIFE

The diversity of the landscape provides numerous biotopes for a great wealth of fauna. The Montsec Mountain Range has an extremely interesting wildlife population due to the interaction between Mediterranean, which predominate, and Eurosiberian components. This transitional character together with the fact that it constitutes the southern distribution boundary for many Pyrenean species, such as the Pyrenean newt (Euproctus asper) and the yellow-billed chough (Pyrrhocorax graculus), or the northern limit for others, such as the black wheatear (Oenanthe leucura), determine the formulation of unique biocenoses.

In these areas, for example, species as varied in nature as the Mediterranean beech marten (Martes foina), and the Euro-Siberian pine marten (Martes martes) live together. There's a wide variety of predators (carnivores and birds of prey). For example, the otter (Lutra lutra), which lives in the two rivers that cross this natural area.

Notably, the hygrophytic colonies (reed beds) in the Terradets reservoir are an important nesting and wintering ground for a large number of water birds such as the great cormorant (Phalacrocorax carbo). Among the fish population inhabiting the reservoir, the stone loach (Noemacheilus barbatulus) is a very interesting species.

There is an abundance of cliffs, which are a vital environment for valuable rupicolous wildlife, as well as caves and chasms that allow remarkable cave wildlife to flourish that in some cases are unique to Catalonia. In particular, it hosts more than half of the Catalan species of chiropters, such as the greater horseshoe bat (Rhinolophus ferrumequinum) and the lesser horseshoe bat (Rhinolophus hipposideros); it is also one of the most important wintering areas in Catalonia for the cave bat (Miniopterus schrebersi).

Invertebrate wildlife is especially rich in cave biotopes and is highly diverse, with numerous endemic species: Pre-Pyrenean cave beetles from the genus Troglocharinus, rare and endangered lepidoptera, such as Chemarina caligenaria, as well as rare, endemic molluscs such as Moitessiera rollandiana, Xeroplexa ripacurcica montsicciana; myriapods, etc. Other protected invertebrates in Montsec are the European freshwater crayfish (Austropotamobius pallipes), longhorn beetles Cerambyx cerdo and Lucanus cervus, and the lepidoptera Graellsia isabellae.