Phenological Shifts in Wood Formation Tracked by Frost Rings Across Two Centuries

Dataset showing the year and the calendar day (DOY) of each frost ring occurance along with species and site. Tree age at the moment of frost occurrence (Age), and the relative frequency of frost rings, calculated as the number of frost rings per year divided by the number of sampled trees of each species and site (Frequency) are reported. R script of the linear mixed model and linear model used are reported.