Worldwide drought events causing tree growth decline and mortality are altering the carbon (C) balance of forest ecosystems. One unexplored aspect of trees’ vulnerability is whether responses to drought may be linked to species’ niche breadth. Using the most severe 2015-2016 El Niño drought event in the last 70 years in Patagonia, we determined pre- and post-drought growth, C reserves, wood isotopes, and vessel diameter in eight angiosperm tree species of contrasting niche breadth across a sharp precipitation gradient in southern Chile. All species responded in unison after the drought with a non-water-conservative response, maintaining growth and C reserves, decreasing δ13C, and increasing both vessel diameter and the soluble sugars:starch ratio relative to pre-drought. We unequivocally showed a functional coordination of organisms’ vital traits, a drought-induced acclimation based on starch conversion into soluble sugars in all of the tree species we examined, regardless of their niche breadth and habitat preference.