Ringwidth

Ringwidth is the radial width of a growth ring in a circular structure, most commonly the distance between successive boundaries of annual growth in woody plants. Measured along a radius from the pith toward the bark, ringwidth is typically expressed in millimeters or micrometers and serves as a quantitative proxy for a tree’s past growth conditions. In dendrochronology and wood science, ringwidth data are used to reconstruct climate signals, study growth patterns, and support age determination.

Measuring ringwidth involves sampling with cross-sections or increment cores. Ring boundaries are identified as changes in wood structure or color, and the radial distance between consecutive boundaries is measured with calipers, micrometers, or image-analysis software applied to scanned cross-sections. High-precision measurements may reach hundredths of a millimeter. Ringwidth series are then standardized or detrended to remove age-related growth trends, yielding ring-width indices used for chronology construction. Cross-dating aligns rings to exact calendar years, enabling interpretation of climate- or event-driven signals.

Applications include climate reconstruction, forest management planning, and ecological research. Interpretations must account for confounding factors such as tree age, competition, site quality, and disturbance. False rings and missing rings can complicate analysis, requiring careful verification and, often, supplementary data from other rings or proxies.

See also: Dendrochronology, Tree ring, Annual ring, Xylem.