Urban ecology is a new w:science applying to cities concepts which were previously only applied to natural systems.
It is often considered w:ecology could only apply to natural areas and w:natural resources. But, why not considering the w:city as a human w:ecosystem ? Urban ecology would then be the science aiming at seeking, maintaining, or restoring natural equilibrium, much more than just a way to take care of nuisances.
The city is an ecosystem in itself. When one apply pressure on one point, it is the whole city which is disturbed. Habitat is linked with industry, itself linked to trade, itself linked to transport.