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

Fabian Gruber,Elisabeth Schaber,Jasmin Baruck,Clemens Geitner

doi:10.3390/soilsystems3010018

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.

Highlights

Information on soil, a non-renewable resource, is of increasing importance due to growing utilization pressure as well as climate change
We presented the soil function assessment tool SEPP, and evaluated the extent to which local terrain parameters and landform classes can influence or recreate the level to which a soil fulfills certain soil functions
For each of the 14 soil functions assessed by SEPP, the presented approach highlights those topographic attributes which are best suited for use as explanatory variables to model fulfillment levels

Summary

Introduction

Information on soil, a non-renewable resource, is of increasing importance due to growing utilization pressure as well as climate change Both developments pose a risk to soils as they can lead to soil degradation such as erosion, compaction, contamination, and soil sealing [1,2]. In order to maintain soil quality it is necessary to know where, and where not, certain practices are applicable, and to adjust land use planning appropriately. For this purpose, within the last two decades different methods to assess soil functions have been developed [3,4] and turned out to be invaluable tools to integrate soil-related issues in decision-making processes [5]. Methodical differences exist in terms of selection and definition of soil

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