Mapping Urbanization as an Anthropedogenetic Process: A Section through the Times of Urban Soils

Antoine Vialle,Mario Giampieri

doi:10.17645/up.v5i2.2848

Abstract

Current trends of spatial planning policies give a strategic role to soils, the multifunctionality of which must be considered as a crucial driver facing cities’ forthcoming social-ecological transition. However, soils within urban areas are insufficiently studied as a long-term record of environmental history and heavy anthropization. This article investigates the extreme qualitative variability of urban soils by presenting a conceptual model and cartographic workflow highlighting soil evolution processes as a value which co-variates with urbanization. Based on a case study in West Lausanne (Switzerland), the layers and map series of an atlas underscore the applicability of different types of information and spatial analysis for documenting the influence of anthrosediments and land cover changes. Combined with empirical profile descriptions, such a consolidated concept map defines a template, in the form of a complex spatio-temporal figure, on which to apply the state factor approach. Instead of using a simple spatial transect or gradient, the increasing anthropic dominance over original landscape conditions is explained using a section through time. An urban anthroposequence consequently retraces contrasting soil development pathways as a coherent bundle of historical trajectories. Such a narrative integrates various facets of land use, including one-off construction techniques and recurring maintenance practices, planning tools, and morphologies, into a specific ‘project for the ground’ which brought forth the mixed mesh of the Swiss Plateau ‘cityterritory.’ Ultimately, the dynamic vision conveyed by these intertwined soil–urbanization coevolution trajectories outlines opportunities for the regeneration of the resource deposit made up of both West Lausanne’s urban fabric and its soils as a palimpsest.

Highlights

Documenting and Projecting Urban Soils as a Long-Term Record of Environmental History and Heavy AnthropizationMotivated by ever-increasing soil degradation due to past and present urban growth dynamics (Gardi, 2017), the current trend of spatial planning policies at the Swiss and European levels is to promote increased soil protection (European Commission, 2016; Swiss Spatial Planning Act, 2019)
We propose to synthesize the diverging combinations of this causal chain in the form of a flow chart diagram presenting various representative trajectories, which depend on urban history and which will be exemplified below
In the forthcoming developments of the research, the urban soil map could be interpreted in terms of soil functionalities and their related capacity to deliver ecosystem services

Summary

Introduction

Motivated by ever-increasing soil degradation due to past and present urban growth dynamics (Gardi, 2017), the current trend of spatial planning policies at the Swiss and European levels is to promote increased soil protection (European Commission, 2016; Swiss Spatial Planning Act, 2019). In order to fill these epistemological and methodological gaps, this article will highlight the human history of urban soils by (I) synthetizing a causal chain model of urbanization, and its related project, as a crucial factor of pedogenetic processes and by, (II) retracing urban soils’ specific historical trajectories according to a cartographic narrative constructed from various source documents This dynamic vision will be explored through the creation of an atlas based on the case study of West Lausanne district in the canton of Vaud, Switzerland. Pedology comprehends soil transformation according to Jenny’s model (Jenny, 1941) defining five external state factors of pedogenesis—climate, biology, topography, lithology or parent material (PM), and time—the influence of which can be studied in the form of a sequence The combinations of these factors trigger different pedogenetic processes, leading to various soil evolution or development pathways (DP) including specific biogeochemical characteristics and associated functional properties, which can be interpreted as ecosystem services. Tors were synthesized into a new concept map to spatialize the main soil historical trajectories, effectively distilling the workflow presented in this article

Mapping Time

Connecting Soils’ Contrasted Development Pathways to Historical Trajectories

Conclusions