How and to What Extent Does Topography Control the Results of Soil Function Assessment: A Case Study From the Alps in South Tyrol (Italy)

Abstract

Soil function assessments (SFA) are becoming increasingly important as a tool to integrate soil-related issues in decision-making processes in order to maintain soil quality. We present the SEPP (Soil Evaluation for Planning Procedures) tool, which calculates a level of fulfillment for 14 soil functions based on the information generally collected in soil pit descriptions. By using a statistical modeling approach based on support vector machine classification, we investigate how and to what extent topography, as representated by local terrain parameters and landform classes computed with the GRASS GIS tool r.geomorphon algorithm, controls soil parameters and hence the output of the SEPP tool. A feature selection procedure is applied which highlights those topographic attributes best suited for modeling the various soil function fulfillment levels. By evaluating the model for each soil function using cross-validation we show that the prediction accuracy varies from function to function. While some terrain attributes are directly implemented in the SFA algorithms of SEPP, others are implemented indirectly due to the link between topography and land use. Minimal curvature and slope were found to be first indicators of function fulfillment level for a number of soil functions.

Soil function assessment in high‐mountain environments: Testing the SEPP tool in a ski resort in the Italian Alps

“…Although the latter is more common, it does not allow for a comparison of soils deeper than 1 m with shallower soils. More details regarding the SEPP tool and the assessed soil functions are provided in the SEPP user manual (Supporting Information) and by Gruber et al (2019), who applied the tool. However, an updated version of the SEPP tool – in comparison to the version used by Gruber et al (2019) – was used in this study, where the ordinal scale was inverted to match the logic of SFAs in Germany, Austria and Switzerland (see BayGLA and BayLfU, 2003; Greiner et al, 2018; Haslmayr et al, 2016), with 1 representing a low and 5 representing a high level of function fulfilment.…”

“…More details regarding the SEPP tool and the assessed soil functions are provided in the SEPP user manual (Supporting Information) and by Gruber et al (2019), who applied the tool. However, an updated version of the SEPP tool – in comparison to the version used by Gruber et al (2019) – was used in this study, where the ordinal scale was inverted to match the logic of SFAs in Germany, Austria and Switzerland (see BayGLA and BayLfU, 2003; Greiner et al, 2018; Haslmayr et al, 2016), with 1 representing a low and 5 representing a high level of function fulfilment. The underlying, sometimes slightly modified, methods were originally developed in Germany and published by Ad‐hoc‐AG Boden (2000), BayGLA and BayLfU (2003), BVB (2005), Gerstenberg and Smettan (2005), Lehmann et al (2008), Müller and Waldeck (2011), and Umweltministerium Baden‐Württemberg (1995).…”

“…T A B L E 2 (Continued) Gruber et al (2019), who applied the tool. However, an updated version of the SEPP tool -in comparison to the version used by Gruber et al (2019) -was used in this study, where the ordinal scale was inverted to match the logic of SFAs in Germany, Austria and Switzerland (see BayGLA and BayLfU, 2003;Greiner et al, 2018;Haslmayr et al, 2016), with 1 representing a low and 5 representing a high level of function fulfilment.…”

“…The Soil Evaluation for Planning Procedures (SEPP) SFA tool, developed by the Department of Geography at the University of Innsbruck (Geitner et al, 2010–2020), was originally designed to support decisions regarding land‐use planning. To date, the SEPP tool has already been applied in Alpine regions for environmental impact assessment (in Austria) and scientific studies (in Italy) (Gruber et al, 2019). The results of SFA performed using the SEPP tool were reasonable and provided a sound differentiation among most of the assessed soil functions.…”