Weathering modulates soil microbial biodiversity in a Sygera Mountain alpine forest, Tibetan Plateau

Alpine ecosystems are highly vulnerable to global change. In alpine ecosystems, weathering (as represented by weathering indices reflecting the integrated product of chemical, physical, and biological processes) associated with biotic activity, is a critical factor explaining soil environmental conditions. However, the contribution of weathering to explaining soil biodiversity in alpine ecosystems remains poorly quantified. Here, we assessed the contribution of weathering to explain prokaryotic and eukaryotic diversities across an elevational gradient in an alpine forest. Notably, along an elevational gradient, we found significant negative relationships between weathering and climatic variables, challenging the conventional unidirectional paradigm of climate-dominated weathering processes. The inverted weathering index of Parker negatively correlated with prokaryotic diversity (P = 0.006, R² = 0.30). Variation partitioning analysis revealed that weathering explained 17 % of the variance in prokaryotic diversity, 36 % in eukaryotic diversity and 13 % in multidiversity. Structural equation modeling further indicated that weathering had significant standardized direct effects on prokaryotic (R = 0.36) and eukaryotic diversities (R = 0.49), respectively. Our study demonstrates the critical role of weathering in shaping prokaryotic and eukaryotic diversities, particularly through regulatory mechanisms independent of climatic variables, emphasizing its importance for understanding and conserving soil biodiversity in alpine ecosystems facing global change.