资源环境科技发展态势分析平台

Hydroclimate variability in tropical South America is strongly regulated by the South American Summer Monsoon (SASM). However, past precipitation changes are poorly constrained due to limited observations and high-resolution paleoproxies. We found that summer precipitation and the El Niño - Southern Oscillation (ENSO) variability are well registered in tree-ring stable oxygen isotopes (δ¹⁸O_TR) of Polylepis tarapacana in the Chilean and Bolivian Altiplano in the Central Andes (18-22ºS, ∼4500 m a.s.l.), with the northern forests having the strongest climate signal. More enriched δ¹⁸O_TR values were found at the southern sites, likely due to the increasing aridity towards the south-west of the Altiplano. The climate signal of P. tarapacana δ¹⁸O_TR is the combined result of moisture transported from the Amazon Basin, modulated by the SASM, ENSO and local evaporation, and emerges as a novel tree-ring climate proxy for the southern tropical Andes.