Urban soil resources of medium-sized cities in Poland: a comparative case study of Toru\u0144 and Zielona G\xf3ra

Abstract

PurposeDespite the many studies of urban soils, a comparative analysis for cities of a similar size has not yet been conducted. Thus, the aim of this review paper was to compare the soil distribution patterns in the area of two medium-sized Polish cities (Toruń and Zielona Góra). The authors attempted to answer the question of how natural and technogenic factors contributed to the transformation of urban soils and what the similarities and differences are between these two studied cities.Materials and methodsFirst, both the natural and the human-related (including historical) factors influencing the soil formation in the studied cities were analysed. Then, a comparison of the degree of transformation of the urban soil environment was presented. The data obtained by the authors during nearly two decades of research (over 200 soil profiles) were used.Results and discussionIntensive development of the built-up areas in Toruń brought heavy and long-term transformations of soils, which demonstrate the typical properties of Urbic Technosols, Ekranic Technosols and other technogenic soils. Zielona Góra showed a similar state of soil transformation over a considerably smaller area. Currently, the differences in the soil properties in many built up areas have been blurred, despite the habitat and historical base. The similarities of the soil properties concerned, in particular, a high content of skeletal remains (from a few to over 30%), elevated pH (in KCl) values (even above 8.0) and the artificial soil horizons formation. Both cities struggle with similar problems regarding the changes in the land use within the areas covered by these soils.ConclusionsIt was found that, despite the significant habitat and historical differences between the two studied cities, most of the urban soils, especially Urbic Technosols, Ekranic Technosols and Regosols (Relocatic and Technic), are characterised by similar morphology and properties. The most important differences are the time and scale of the area transformation, which influence the extent of Technosols and Anthrosols within the city borders. The most distinct differences concern the natural and slightly transformed soils, which are the results of various soil-forming factors.