You are here:
The Vertical Structure of Urban Soils - Portland
Citation:
Herrmann, D., L. Schifman, W. Shuster, AND S. Dadio. The Vertical Structure of Urban Soils - Portland. Presented at Ecological Society of America, Portland, OR, August 06 - 11, 2017.
Impact/Purpose:
F.S. Chapin et al.’s popular textbook Principles of Terrestrial Ecosystem Ecology states that the parts of soil are “arranged in a relatively predictable vertical structure” (p. 58 in the 2002 edition). This theoretical pattern for vertical soil structure (e.g., A-B-C ordering of horizons) provides a basis for comparison with our observed urban soil data as to how urban soils differ from reference soil pedons “stack” vertically. This work will inform urban ecological research methods while at the same time advance our knowledge of urban ecosystems. We performed a soil taxonomic assessment of 391 deep soil cores (up to 5-m depth) collected from two Midwestern U.S. cities (predominantly Alfisols) as a part of a larger sampling of 12 cities representing the 10 major soil orders across the U.S., Puerto Rico, and the Republic of the Marshall Islands. The likely reference soil series (i.e., the soil series present prior to urbanization), was identified for each observed soil pedon. The reference soil pedons were further described by soil taxonomy data for agricultural and wildlands land uses, and gathered from the NASIS database. We hypothesized that urbanization has modified the vertical arrangement of soil horizons to decrease vertical heterogeneity (e.g., number of horizons, type of horizons), and that modification would be greatest near the surface and decrease in their apparent impact with depth.
Description:
We compared observed to reference pedons for two cities (Detroit MI; Cleveland OH), where it was clearly illustrated that urban soils had fewer soil horizons than their non-urban references. The ordering of observed urban soil horizons was distinct from both the theoretical (A-B-C) and respective reference soil series. Specifically, A-C transitions with absent B horizons was more common in urban than non-urban soils. B horizons were often absent or their first occurrence was as a substratum of the first C horizon. The simplification of horizonation in urban pedons as absent or unique classifications of B horizons accounted for a major proportion of contrast to non-urban soils. If these patterns hold across more cities/soil orders, our results may indicate a generalization of disturbance pattern, and a need to revisit the conventional conception of vertical soil structure, both toward a more nuanced understanding of urban ecosystems. By identifying the patterns that are found across cities, urban soil vertical structure may be conditionally predictable, much like their agricultural counterparts.