Whether growing along the rim of the Grand Canyon or living in the mist with California’s coastal redwoods, Douglas fir trees are consistently sensitive to drought conditions that occur throughout the species’ range in the United States, according to a study led by a researcher at UC Davis. The study, published Monday in the journal Proceedings of the National Academy of Sciences, provides direct evidence of the negative impact of water stress on forest ecosystems. It also pinpointed which conditions are causing low growth among Douglas fir trees.