Three Tides: The Development and State of the Art of Urban Ecological Science

The development of the science of urban ecology in the United States has not been continuous. We identify three specific periods during the twentieth century when the application of ecological science to understanding the structure and dynamics of urban areas gained momentum. We begin with the Chicago School of the 1920s and 1930s that applied concepts from ecological science to understand the spatial differentiation of people and land uses. The second period considered the city as a system. The third, and contemporary period, advocates an inclusive approach that considers cities as integrated ecological and social systems. We use the metaphor of tides to frame our discussion of the developments that allowed the tide to come in and that perhaps also caused that tide to ebb. Each tide however, contributed approaches and understandings that were ready to be used upon the arrival of the next tide.