Asian Continental Isoscapes of Tree-Ring δ¹⁸O: Implications for Paleoclimate and Paleoenvironment

Abstract Continental-scale isoscapes of tree-ring oxygen isotopes (δ¹⁸OTR) are crucial for understanding atmospheric circulation dynamics, interpreting climatic significance, and tracing wood provenance. However, continental-scale δ¹⁸OTR isoscapes remain underdeveloped. We compiled 313 multi-year averaged δ¹⁸OTR records across Asia and generated isoscapes using two machine learning approaches: XGBoost and Random Forest. Results reveal a “sandwich” pattern: lower values at high (>50°N) and low latitudes (<30°N), higher values at mid-latitudes (30–50°N). This pattern closely resembles the distribution of precipitation δ¹⁸O (δ¹⁸OP). Correlation and commonality analyses confirm δ¹⁸OP as the primary driver of δ¹⁸OTR isoscape patterns across Asia. Continental-scale δ¹⁸OTR-elevation relationships are generally insignificant, except in Indian Summer Monsoon regions showing significant negative correlations (r = –0.69, p < 0.05). These findings suggest δ¹⁸O-based paleoaltimetry reconstructions work best in regions with dominant moisture sources such as Indian Summer Monsoon regions. This study provides Asia’s first continental-scale δ¹⁸OTR isoscapes, offering valuable insights for paleoclimate, paleoenvironment and dendroprovenancing research.