Spatiotemporal hydroclimatic signals in native Andean forests of Argentina inferred from carbon and oxygen stable isotopes

Understanding past hydroclimatic variability is important for sustainable water resource management in semi-arid mountainous regions. This study characterizes the contrasting hydro-thermal signals recorded by stable isotopes from two strategically selected tree-ring chronologies at two contrasting sites in the Argentine and Central Andes. We analyze a 212-year δ¹³C record from Fitzroya cupressoides in the humid forests of northern Patagonia (950–1060 m a.s.l.) and a 122-year δ18O record from Polylepis tarapacana in the arid Altiplano (3500 m a.s.l.). Using Pearson correlation analysis, we identified significant regional climate sensitivities for both species against the CRU TS 4.08 (precipitation) and HadCRUT5 (temperature anomaly) datasets. F. cupressoides δ¹³C integrates a multi-seasonal ‘memory effect’ linked to winter moisture recharge (r = –0.40, p = 0.030) and a robust sensitivity to summer thermal stress (r = 0.61, p = 0.011). Conversely, P. tarapacana δ18O acts as a direct sensor of the convective ‘amount effect’ during the summer monsoon (r = –0.48, p = 0.037) while remaining highly sensitive to early summer thermal conditions (r = 0.50, p = 0.039). To validate the regional representativeness of these findings, we further evaluated the proxies through spatial correlation fields using gridded precipitation, temperature, runoff (G-RUN), and soil moisture (CLM). The spatial correlation analysis is consistent with regional-scale dynamics and large-scale atmospheric forcing, specifically the Southern Annular Mode and the South American Summer Monsoon. This spatial validation demonstrates that these stable isotope records provide essential long-term baselines to understand regional water balance implications and characterize historical hydrological variability, offering a robust scientific foundation to support sustainable water resource management in climate-sensitive Andean environments.