Uso di dati di monitoraggio e variabili degli habitat per la costruzione di modelli di distribuzione delle specie di uccelli nella regione Marche, Italia

During the last century several populations of birds in Europe have severely decreased, which has been explained with habitat modifications and common use of intensive agriculture. The often rapid changes of the ecosystems can cause the loss of several animal species even in few years, and the reduction of species diversity is currently considered one of the greatest ecological problems on a worldwide scale. Therefore, understanding the relations between the habitat variables and the animal communities that use them for breeding, feeding or taking refuge is of the highest importance. In this study we have used the data collected in 2004-2005 from monitoring campaignes of 36 bird species: these form a basic knowledge of the species distribution on a regional scale, and have allowed to realize maps elaboration integrating the vegetation physionomy and structure in the study areas, which are all included in SIC and ZPS of the Marches region. A model of spatial species distribution and of prediction of the suitable habitat for each species has been obtained by means of regression analysis, statistical models and GIS analysis. The model is based on the study of 185 atlas cells (1 km square), all of which have been characterized for presence/absence of bird species, vegetation typologies richness, type of the vegetation covering, edge density (as a fragmentation measure), road density and building density. Maps of the real and potential distribution of each species have been obtained: the species potential presence in every unity is associated with a probability value. Suitable habitat maps for each species have also been realized. This distribution model can be used to locate sites of species potential occurrence (for future monitoring), or even habitats which should be especially considered for conservation because ecologically important for the species of interest. The model may also help to develop plans and management strategies for preserving the functionality of the ecosystems. �� Societ\`{a} Italiana di Scienza della Vegetazione.