Functional diversity in Keihanshin Metropolitan Area

Diversity is one of the defining characteristics of complex adaptive systems – systems made up of heterogeneous agents whose interactions form a dynamic network resulting in emergent behaviour. Recent research shows that various types of diversity increase with the scale of the system. This paper uses ideas and methods from community ecology to define business types as functional traits and to calculate functional diversity as a measure of the economic diversification in an urban system. It asks how functional diversity changes with the size of the city within an urban region. Using Keihanshin Metropolitan Area in Japan as an example, the paper concludes that while functional diversity scales with city size, it reaches saturation due to the limitations of the business types classification systems. It argues that regardless of the observed saturation, the method can reveal the structural complexity of the city, showing what types of industries form its economy. It also discovers functions common to all cities in the region, and calls for further development of the method by introducing the multidimensional analysis and additional measures of diversity.