A diameter tape (D-tape) is a measuring tape used to estimate the diameter of a cylinder object, typically the stem of a tree or pipe. A diameter tape has either metric or imperial measurements reduced by the value of
π. This means the tape measures the diameter of the object. It is assumed that the cylinder object is a perfect circle. The diameter tape provides an approximation of diameter; most commonly used in
dendrometry
Dendrometry is the branch of botany that is concerned with the measurement of the various dimensions of trees, such as their diameter, size, shape, age, overall volume, thickness of the bark, etc., as well as the statistical properties of tree s ...
.
Diameter tapes are usually made of cloth or metal, and on one side of the tape have diameter measurements and on the other standard measurements (not reduced by π).
Use of diameter tapes
Diameter tapes are used to measure tree stems (
trunk or bole); other parts of trees such as branches and roots; and logs (cut stems).
Standard Diameter Height (SDH)
[http://www.sortie-nd.org/help/manuals/help/data/allometry/standard_diam_height.html. ] is the height at which tree diameter is measured, and is normally called
diameter at breast height
Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements.
Tree trunks are measured at the height of an adult's breast ...
(DBH).
DBH is measured at a fixed height of above the ground in the United States, New Zealand, South Africa, India, and Malaysia; or meters in Australia, Canada, Europe Thailand and Vietnam.
DBH is not usually measured at ground level to avoid measuring a tree's butt swell. Butt swell is where the base of the tree is unconventionally thicker than the rest of the tree. Height and diameter are used to determine the volume of a given tree; measuring above the butt swell is required to provide the most accurate measurement.
For single-stem trees, DBH is a useful and is easily measured. For multi-stem species such as
mallee or other multi-stemmed species, DBH may be inconvenient because of a large number of stems and difficulty of access, and a lower or higher measurement height may be more practical.
DBH measurements can be used with other measurements, such as height, to estimate the volume of wood in an individual tree. Usually DBH and height of the trees in a plot or
quadrat
A quadrat is a frame, traditionally square, used in ecology, geography and biology to isolate a standard unit of area for study of the distribution of an item over a large area. Modern quadrats can for example be rectangular, circular, or irregul ...
is measured and used to estimate wood volume for the plot, which can be in turn used to estimate the wood volume in a larger area.
DBH measures can be used to calculate
basal area
Basal area is the cross-sectional area of trees at breast height (1.3m or 4.5 ft above ground). It is a common way to describe stand density. In forest management, basal area usually refers to merchantable timber and is given on a per hectar ...
.
Measuring diameter
To measure the diameter of a tree, the diameter tape (diameter side facing user) is wrapped around the tree, in the plane perpendicular to the axis of the
trunk at above ground (or , depending on the location) . Where the number "0" aligns with the rest of the tape, the diameter can be read directly from the tape, for a relatively round and smooth tree trunk as shown.
See
Tree girth measurement Tree girth measurement is one of the most ancient, quickest, and simplest of foresters' measures of size and records of growth of living and standing trees. The methods and equipment have been standardized differently in different countries. A popul ...
for some cautions about placement, and errors that may be introduced, by reporting this diameter for a trunk, or any material, that is not nearly circular.
Precision diameter tapes
Precision diameter tapes are used for measuring the true diameters of both round and out-of-round forms. Used in the metal working industry, these tapes are precision tools made of 1095 clock spring steel.
The precision-diameter gages consist of a narrow metal ribbon bearing special graduations
vernier scale
A vernier scale, named after Pierre Vernier, is a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation, thereby increasing resolution and reducing measurement unce ...
. The vernier scale allows the user more accurately measure diameter.
The tapes are checked over master gauges at accuracy for standard tapes up to .
Precision diameter tapes are used in precision or advanced manufacturing industries, such as aero-space field and the plastic pipe industry.
See also
*
Biltmore stick
The Biltmore stick is a tool used by foresters to estimate tree trunk diameter at breast height. The tool very often includes a hypsometer scale to estimate height as well. It looks much like an everyday yardstick. With practice a Biltmore stick i ...
*
Timber cruise
Forest inventory is the systematic collection of data and forest information for assessment or analysis. An estimate of the value and possible uses of timber is an important part of the broader information required to sustain ecosystems. When taki ...
*
Tree girth measurement Tree girth measurement is one of the most ancient, quickest, and simplest of foresters' measures of size and records of growth of living and standing trees. The methods and equipment have been standardized differently in different countries. A popul ...
*
Tree allometry
Tree allometry establishes quantitative relations between some key characteristic dimensions of trees ( usually fairly easy to measure) and other properties (often more difficult to assess). To the extent these statistical relations, establishe ...
References
{{DEFAULTSORT:Diameter Tape
Forest modelling
Dimensional instruments
Forestry tools