Oblique geographic coordinates as covariates for digital soil mapping

<p>Decision tree algorithms, such as random forest, have become a widely adapted method for mapping soil properties in geographic space. However, implementing explicit spatial trends into these algorithms has proven problematic. Using <span class="inline-formula"><i>x<...

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Bibliographic Details
Main Authors: A. B. Møller, A. M. Beucher, N. Pouladi, M. H. Greve
Format: Article
Language:English
Published: Copernicus Publications 2020-07-01
Series:SOIL
Online Access:https://soil.copernicus.org/articles/6/269/2020/soil-6-269-2020.pdf
Description
Summary:<p>Decision tree algorithms, such as random forest, have become a widely adapted method for mapping soil properties in geographic space. However, implementing explicit spatial trends into these algorithms has proven problematic. Using <span class="inline-formula"><i>x</i></span> and <span class="inline-formula"><i>y</i></span> coordinates as covariates gives orthogonal artifacts in the maps, and alternative methods using distances as covariates can be inflexible and difficult to interpret. We propose instead the use of coordinates along several axes tilted at oblique angles to provide an easily interpretable method for obtaining a realistic prediction surface. We test the method on four spatial datasets and compare it to similar methods. The results show that the method provides accuracies better than or on par with the most reliable alternative methods, namely kriging and distance-based covariates. Furthermore, the proposed method is highly flexible, scalable and easily interpretable. This makes it a promising tool for mapping soil properties with complex spatial variation.</p>
ISSN:2199-3971
2199-398X