Our findings indicate that reintroducing frequent fire reduces tree water stress without inhibiting growth response to prolonged aridity. This suggests that frequent-fire regimes may help forests better withstand increasingly hot and dry conditions expected under climate change.

Growth responses varied with climate and topography while water use efficiency varied with climate, topography, and competition. Trees were more water-efficient in stands with more small trees, which helped explain greater water stress in denser, fire-excluded forests. 4/n

Fire-maintained trees grew faster to begin the first drought, but growth rarely differed among trees for the remaining 21 years. Interestingly, similar growth rates occurred as fire-excluded trees became increasingly more efficient with water, signaling greater water stress. 3/n

We quantified stomatal and growth responses to 4-year and 7-year droughts using tree cores, which let us compare wood carbon isotopes and ring-widths among trees over several decades. We also modeled these responses against climate, topography, competition, and fire history data. 2/n