Dataset for Blomdahl et al. 2022. Drivers of forest change in the Greater Yellowstone Ecosystem. Journal of Vegetation Science. See publication for site description and methods. Descriptions for variables in “trees_seedlings.csv”: Plot_ID: Plot identifier. Nomeclature follows transect name and plot number. ECO="Ecotone" transect, SBM="South Bird Mountain" transect. Year_Sampled: Samples collected 2017-2019. Tree_ID: Identifier for unique trees and seedlings. Core: Tree core sample identifier. Applies only to trees (cores not taken from seedlings). Generally, 2 cores were taken per Tree >5 cm DCH, though sometimes up to 4 were collected if a sample was rotten. Sample_ID: Identifier for unique samples, some of which come from the same tree (for unique individuals: "Tree_ID"). Applies to trees and seedlings. Form: Stems >5 cm diameter at coring height (DCH), coring height=30 cm; Seedlings >30: Stems <5 cm DCH and >30 cm in height (sometimes referred to as "saplings"); Seedlings <30: Stems <30 cm in height Species: ABLA=Abies lasiocarpa, PIAL=Pinus albicaulis, PICO=Pinus contorta, PIEN=Picea engelmannii, PSME=Pseudotsuga menziesii Diam_30_cm: Diameter (cm) at 30 cm sample height. Diam_0_cm: Diameter (cm) at 0 cm sample height (i.e., the base). Only seedlings were measured at base, not trees. Seedling_Ht_cm: Length of seedling stem (cm). Bark_Thick_cm: Bark thickness (cm). Not recorded in 2018. Bark thickness assumed to be <0.1 cm for seedlings. Live_Dead: Live/Dead status when sampled. L=Live, D=Dead. Canopy: Canopy position. D=Dominant, C=Codominant. S=Suppressed. Not recorded in 2017. All seedlings assumed suppressed. Outer_Ring: Last complete year of growth, generally one year prior to Year_Sampled for live trees. Mortality year for dead trees. Inner_Ring: Year of innermost ring measured in tree core sample measured at 30 cm sample height. Does not apply to seedlings, which were sampled as cross sections, and therefore the pith was always measureable. Pith_30: Year of the first ring of the tree or sapling, measured at 30 cm sampling height. Pith_0: Year of the first ring of the seedling, measuring at 0 cm sampling height (i.e., the base). Applies only to seedlings, which were destructively sampled at the base. Estab_Year: Estimated year of establishment for trees and saplings, same as Pith_0 for seedlings. See methods of Blomdahl et al., 2022, for how establishment year was estimated. Age: Estimated age of the tree.