Historical soil erosion events in border polje revealed by geochemical fingerprint analysis of soil profiles

Understanding soil erosion history in ecologically fragile karst regions is essential for sustainable land management. The potential use of border polje (BP) soil profiles as reliable records of erosion deposition remains uncertain. This study investigated the geochemical characteristics of limestone and siltstone weathering profiles on both sides of the BP, using geochemical fingerprints to quantify BP soil source proportions and erosion changes. Key findings include (1) The karst and non-karst soil profiles on the slopes on each side of BP exhibit distinct geochemical signatures, with weathering indices indicating chemical weathering processes originating from limestone and siltstone, respectively. (2) Discriminant analysis and conservative element testing achieved accurate differentiation between the limestone and siltstone weathered soil sources, with a model goodness-of-fit above 80%, confirming the effectiveness of geochemical fingerprinting for determining soil provenance. (3) Siltstone-weathered soils dominate the bulk of BP soils, with small amounts of weathering products from limestone near the karst hills. (4) A marked increase in weathered material from both karst and non-karst sources at depths of 1.2–1.4 m, along with charcoal presence, suggests intensified erosion following historical fire events in the area. These results affirm the feasibility of the use of BP soil profiles as records of historical erosion, with geochemical fingerprints capturing shifts between karst and non-karst hill contributions. This study highlights the potential of BP soil profiles as archives of environmental changes, providing a framework for reconstructing historical landscape dynamics in complex terrains.