1 A model of change used in urban ecology to represent the effects of immigration on the social structure of an urban area. Invasion and succession involve a chain reaction, with each preceding immigrant wave moving outwards and being succeeded by more recent, poorer immigrants (R. E. Park, E. W. Burgess, and D. McKenzie 1925/1974). This model saw immigrant enclaves as transitional stages on the road to eventual acceptance and integration in the larger (American) society (Clark in R. Waldinger and M. Bozorgmehr, eds 1996). Van Kempen (2007) J. Housing & Built Env. 22, 1 argues that divided cities cannot be explained without using concepts like invasion, succession, and filtering.

2 In plant ecology, the introduction and subsequent spread of a species. Diamond (1974) Science 184 provides a dynamic model of successional processes, and R. H. Groves and F. Di Castri (1991) distinguish between invasion and succession.