The 'niche' city. A multifactor spatial approach to identify local-scale dimensions of urban complexity

Metropolitan systems were constituted by spatial components with different specialization 'niches' based on characteristic attributes (demography, economic structure and performances, socio-spatial patterns, urban morphology, topography, land-use and spatial planning). The present study investigates the multiple dimensions of urban complexity in the light of the 'ecological niche' theory, assessing the spatial structure of a vast ensemble of socioeconomic and territorial indicators that reflect processes of growth and change in contemporary cities. To assess jointly patterns and processes of urban expansion and their impact on recent socioeconomic transformations at the local scale, Athens, the capital of Greece, was taken as a prototype of metropolitan systems with a socioeconomic context evolving under specific form-function relationships. An exploratory framework based on principal component analysis, hierarchical clustering and spatial autocorrelation indexes was used to identify and characterize 8 dimensions that reflect different specialization 'niches' at local scale. Clusters of municipalities were identified according to the dominant socioeconomic dimensions and urban specialization niches. A composite index of urban complexity was finally proposed with the aim to outline latent spatial gradients associated with settlement morphology, social diversification, local development and economic performances. The empirical results of this study contribute to a better understanding of complex urban systems, providing the necessary knowledge base to support implementation of policies for sustainable development of metropolitan regions.