The environment of the historical region of Marmilla has been strongly transformed by human interference. The cultivation of cereal has been practiced in the region since ancient times and has greatly contributed to defining the relationship between man and its environment, to the extent that it is inconceivable to consider one without the other. The boundary between nature and culture in this area is blurred, but the traces of a long history can be seen in the fragmentation of farmland, the branching of a stream or the disposition of the olive groves on the steep slopes of a hill. Man's hands have left their mark in the shape of the trees and the taste of the fruit. It is obvious how easy it is for a crop to be absorbed by the forest or for a path to be covered by bushes when men do not intervene.
In rural areas around the villages, located at the foot of the plateau, the distinction between the domestic and the wild is uncertain, especially when it comes to animals. This is true in the case of the famous Giara horses and their relationship with men, who have been catching, marking, using, and releasing these horses throughout the centuries.
A similar situation can be seen in the relationship between the protection and use of areas that were inaccessible for cultivation. Even if they cannot be considered to be productive areas, local people have been using them for herding as well as a source of game, cork, and wood. These spaces have been naturally preserved due to their physical characteristics.
The SCI (Site of Community Importance) of “Giara di Gesturi” is currently presented as a nature reserve. Among its most characteristic natural resources are the forests of corks and oaks, the paùlis, which are temporary ponds which are unique ecosystems, the scalas, which are natural paths that give access to the plateau, and streams that flow across the slopes or form beautiful waterfalls. In particular, it is worth mentioning Cracchera Park in Sini, the beautiful waterfall of Su Strumpu, the wellspring of Mitza Salamessi in Tuili, and the forest of Su Padenti in Albagiara. The sites of scientific interest of Genna Manna - Muru ’e Cubeddu in Nureci, Duidduru in Genoni, and the volcanic emission centers of Zeppara Manna in Genoni and Zepparedda in Tuili can also be included.