The spatial components of demographic change

"In recent years, fertility in developed countries has drastically fallen towards replacement levels, so that further changes play an increasing role in determining the dynamics of population systems. In this paper, the dynamics of multiregional populations are analyzed when occasional perturbations resulting from changes in social and economic conditions exist. A perturbation theory for population models is introduced and the increasing effect of changes in demographic rates in determining the spatial component of the multiregional population growth is shown." The author outlines the critical situations in which perturbations produce drastic demographic changes. Data for Italy are used to show the theory's usefulness in analyzing both short- and long-term effects of changes in vital rates.