Studies of urban systems and of ecological systems have evolved in separate knowledge domains (Alberti 1999a). Although urban scholars have focused extensively on the dynamics of urban systems and their ecology, these diverse urban processes have yet to be synthesized into one coherent modeling framework that allows us to study the resilience of Sllch systems. Disciplinary approaches have not adequately addressed the processes and variables that couple human and natural systems. Urban models designed to explain or predict urban development are still extremely limited in their
ability to represent ecological processes. On the other hand, ecological models vastly simplify human processes. Only as we have begun to pay more attention to the important role of human activities in environmental change have we seen the need to develop an integrated framework for studying the interactions between biophysical and socioeconomic p'rocesses.
A new inter-disciplinaey synthesis is necessary if urban and ecological dynamics are to be integrated successfully. Such a synthesis will allow us to take at least six important steps: