Woody legacies of railroad ties from the Southern Atacama Desert used to strengthen Nothofagus obliqua tree-ring chronologies from Northern Patagonia

During the late Nineteenth and Twentieth centuries there was an intense exploitation of the long-lived Nothofagus obliqua forests in the temperate region of South America due to the quality of their hardwood. This exploitation resulted in degradation of this Northern Patagonian ecosystem with severe biodiversity implications. This also has prevented the development of multicentury N. obliqua tree-ring width chronologies, with implications for regional environmental and paleoclimatological studies. The large-scale manufacturing of railroad ties distributed across Chile drove part of this exploitation. This study evaluated the use of this cultural material from abandoned tracks preserved in the southern Atacama Desert to strengthen the existing N. obliqua tree-ring network in Patagonia. We dated this historical wood using classical crossdating ring-width methods corroborated with wiggle matching of radiocarbon series from railroad tree-rings using the hemispheric ¹⁴C curve. Correlation analysis with climate data and paleoclimate field reconstructions shows a clear hydroclimate signal contained in the resulting regional tree-ring record with a consistent spatial pattern across northern Patagonia. The dendrochronological use of railroad ties preserved in the Atacama Desert opens a new avenue for dendroclimatic studies and highlights its heritage importance as a past environmental archive in southwestern South America.