Cellulosic stable carbon and oxygen isotope values in tree-rings of mature Douglas-fir trees at five sites in western Oregon. This dataset is associated with the following publication: Lee, E.H., P. Beedlow, R.J. Brooks, D.T. Tingey, C. Wickham, and W. Rugh. Physiological responses of Douglas-fir to climate and forest disturbances as detected by cellulosic carbon and oxygen isotope ratios. TREE PHYSIOLOGY. Heron Publishing, Victoria, B.C, CANADA, 42(1): 5-25, (2022).