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 and deposition remains uncertain. This study investigated the geochemical characteristics of soil profiles developed on limestone and siltstone 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 opposite slopes of BP exhibit distinct geochemical signatures, enabling effective tracing sediment sources. (2) Discriminant analysis and conservative tests effectively distinguished contributions from karst and non-karst slopes, with model goodness-of-fit exceeding 90 % in the BP profiles. (3) Non-karst soils dominate BP soils (>78 % on average), while karst soils contribute significantly to deep layers near karst hills (∼50 %), decreasing to < 10 % in the surface layer. (4) Notable changes in karst and non-karst soil contributions at 1.0–1.4 m depths in the BP soil profile, coupled with the presence of charcoal, suggest shifts in sediment dynamics, highlighting the BP's sensitivity to erosional environmental changes. These findings validate the feasibility of using BP soil profiles as records of historical erosion, with geochemical fingerprints capturing shifts in sediment contributions from karst and non-karst hills. This study highlights the potential of BP soil profiles as archives of environmental changes, providing a novel framework for reconstructing historical erosion dynamics in karst regions.