diameterclass

Diameterclass is a term used in forestry and related fields to categorize trees by trunk diameter at breast height (DBH). Each class covers a specific range of diameters, and the collection of all classes across a stand forms a diameter distribution used to describe stand structure, estimate timber volume, and inform management decisions.

Commonly, diameter classes are defined with uniform width such as 2 cm, 5 cm, or 10 cm increments (for example 0–4 cm, 5–9 cm, 10–14 cm). Some inventories use broader or irregular classes to reflect sampling design, age, or species differences. DBH is measured at 1.3 meters above ground; in some regions, smaller stems are measured differently (e.g., sapling diameter at 0.3 m).

The diameter class distribution is often presented as a histogram or stand table showing the number (or basal area) of trees per class; the shape of the distribution (e.g., J-shaped, reverse-J) indicates recruitment and stand dynamics. Calculations often involve converting class data to total basal area or volume using species-specific allometric equations; diameter class data support modeling of growth and yield in rotation planning.

Note: The exact class boundaries and measurement conventions vary by country and inventory protocol, so diameter class specifications should be consulted in respective methodology documents.