Soil Multi-Element Fingerprinting Along Altitudinal Gradients: Insights from The Changbai Mountains, China

Understanding the distribution patterns of soil multi-elements is crucial for assessing the ecological health and biogeochemical processes in mountain ecosystems. Altitudinal gradients provide a natural framework for examining how soil elements respond to environmental variation. In this study, we analyzed the composition of 45 elements (e.g., As, Cd, Cu, Mn, Na and S) in different soil layers along an altitudinal gradient (800–1700 m a.s.l.) on the northern slope of the Changbai Mountains, Northeast China to clarify the altitudinal distribution patterns and identify the key driving factors of soil multi-elements in mountain ecosystems. Most elements exhibited distinct altitudinal distribution patterns, with multiple elements, particularly rare earth elements (e.g., Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd), showing concentration peaks at 1100 m and secondary peaks at 1550 m. In the upper soil layer, the concentrations of multiple elements at low altitudes, 800−1100 m, closely resembled those at middle-to-high elevations (1400–1700 m); however, this similarity decreased in deeper layers, indicating stronger altitude-dependent variation in subsurface elemental distributions. Soil organic matter (OM) was the key driver of element distributions along the altitudinal gradient. Notably, high stratification ratios (SR) of Cd (3.35), S (2.42) and TN (3.36) were elevated across all altitudes, indicating pronounced upper-layer enrichment across elevations. These findings highlight the soil multi-element stratification ratio as an integrative indicator for assessing soil quality and ecological restoration in mountain ecosystems, thereby providing a methodological framework for assessing soil ecological health under environmental gradients.