Depth-Coupled Functional Readiness of Urban Soil Health Evidence

Abstract

The analysis of urban soil health should facilitate decision-making concerning park management, de-sealing, urban forestry, stormwater management, carbon sequestration, and restoration of disturbed soil. Therefore, any analysis of urban soil health requires measurements that reflect chemical, physical, biological aspects, sampling depth, and ecological services associated with urban soils. In this regard, we performed the analysis of urban soil health based on a calculation of a Depth–Function Coupling Portfolio of selected 63 out of 217 papers. The dataset used in this work included data about 61 geographical samples, 59 samples characterized by land use and 51 samples described in terms of their sampling depths. Chemical aspects were reported in 76% of the publications, physical – in 60%, biological – in 44%, soil health indexes – in 37%, and ecosystem services – in 33%. Among land use categories, the greatest number of cases refers to open space (32), park (26), and residential land use (23). Among vegetation types, grass has the largest frequency (48), followed by trees (23) and shrubs (15). Moreover, vertical sampling is limited in more than 70% of samples, where sampling was made not deeper than 20 cm. Only two studies considered soil samples obtained deeper than 120 cm. Soil function coverage index equals 0.507, depth awareness index equals 0.457, the score reflecting the disjunction between soil functions and depth equals 0.469, while the portfolio stress equals 0.500. Ecosystem service proxies have the highest contribution into total measurement deficit (26.8%), followed by soil health indexes (25.2%) and biological measurements (22.4%). Raising the proportion of biological and ecological services covered by urban soil research to 0.60 would increase the soil function coverage index to 0.637. Combined with the depth adequacy value of 0.50, this value will increase depth-awareness index to 0.607 and portfolio stress to 0.284.