Comparative ecological network analysis. Target and vector species and other naturalistic issues.

Urban settlements produce strong alteration of natural environments and of their ecological structures. Land fragmentation and lack of vegetation in most of the soil space create an unsuitable environment for a large quantity of animals normally living in the region. The ecological networks can be classified among the territorial devices able to guarantee the functional and spatial connectivity between the environmental and landscape components, ensuring the continuity of flow in the matrices and contrasting the processes of fragmentation. These strategies are finding wide applications especially in the peri-urban and urban-rural transition zones characterized by the presence of residual ecosystems, which still preserve natural values and facilitate the dispersal processes of plant and animal populations. In this work, two pilot areas located in the peri-urban fringe areas of the cities of Sassari and Nuoro are identified, analyzed and compared. The presence of agricultural areas, gardens and tree-lined avenues offers the possibilities for the realization of ecological networks that are studied according to the theory of complex networks and starting from the characteristics of the two most widespread plant target species in these areas: the Holm oak and the Olive tree. European jay (Garrulusglandularius) and the common starling (Sturnus vulgaris) have been considered as vector animal species. Combining the study of the green areas (patches distribution and size) and the potential distance of dissemination by birds (corridors), two ecological networks were built for the towns of Nuoro and Sassari.