Tree Ring illustration

A photomicrograph illustrates tree rings for years 1504-1520 on a Douglas fir core specimen. The schematic illustrates which components would be measured as earlywood (white) and latewood (black). Note that latewood contains independent variability, particularly evident in years when it is disproportionally wide (e.g., 1506, 1509, 1517) or narrow (e.g., 1508).