Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk of a tree. Diameter is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ... The coniferous Coast Redwood, the tallest tree species on earth. ...

The trunk is measured at the height of an adult's breast; this is defined differently in different situations, with foresters measuring the diameter at 1.3 m above ground, while people measuring ornamental trees usually measure at 1.5 m above ground. In most cases this makes little difference to the measured diameter. A decidous beech forest in Slovenia. ... An ornamental plant is a plant that is grown for its ornamental qualities, rather than for its commercial or other value. ...

On sloping ground, the "above ground" reference point is usually taken as the highest point on the ground touching the trunk, but some use the average between the highest and lowest points of ground.

The diameter is measured with a girthing tape, and actually measures the girth (circumference) of the tree; the girthing tape is calibrated in divisions of π centimetres (3.14159 cm), thus giving a directly converted reading of the diameter. This assumes the trunk has a circular cross-section, which is typically accurate for most plantation trees. The circumference is the distance around a closed curve. ... Lower-case Ï€ (the lower case letter is used for the constant) When a circles diameter is 1, its circumference is Ï€. The mathematical constant Ï€ is an irrational real number, approximately equal to 3. ... A plantation is an intentional planting of a crop, on a larger scale, usually for uses other than cereal production or pasture. ...

DBH is used in estimating the amount of wood volume in a stand of trees.

References

• Hamilton, G. J. (1975). Forest Mensuration Handbook. Forestry Commission Booklet 39. HMSO, London.