PHYTOGEOGRAPHY OF QUERCUS SUBER L. IN LAZIO (CENTRAL ITALY): A CAUSALISTIC APPROACH

Abstract

A descriptive statistical approach to the causalistic distribution of Quercus suber in Lazio (Central Italy), based on presence/absence data and mean values of an array of environmental variables standardized on a geographical 6,9 x 5,5 Km grid, shows that only temperature, precipitation, elevation and slope are significant. At this scale, soil conditions and aspect are apparently no limiting factors to the colonization ability of the species. A simulated potential range, based on this parameterization, identifies a larger area than the one occupied by the species today. It suggests that competition and human disturbance might account for the large gaps and discontinuities in the real range. Since inland disjunct outposts still lie either outside or at the boundary of this simulated range, their establishment is likely to have originated under macroclimatic conditions different from the present day ones.