Topological analysis of the spatial distribution of plant species richness across the city of Rome (Italy) with the echelon approach

It is generally agreed that urban vegetation significantly contributes to the well-being of individuals and society. Therefore, plant species richness in urban environments is a variable of considerable interest to landscape planners and conservation biologists. While all monitoring activities have a spatial context to a varying degree, monitoring of urban plant species richness distribution requires an objective method for defining the boundaries of areas that are species rich or poor compared to their surroundings. By aggregating the cells of tessellated numerical surface variables into hierarchically related topological entities, the echelon approach provides a new way to objectively characterize the structure of spatial data bases and is thus appropriate for monitoring environmental indices such as urban plant species richness. In this paper, we apply the echelon approach to the characterization of the broad-scale spatial distribution of plant species richness across the city of Rome (Italy).