Quadratic Mean Diameter
Quadratic Mean Diameter ( Dq ) is the diameter of the tree of average per tree basal area. This becomes a convenient in that we often have basal are per acre and trees per acre but not the diameters of all the trees.
In imperial units:
$$D_q = \sqrt{ \frac{\frac{ba}{tpa}}{0.005454154}}$$
where: Dq is the Quadratic Mean Diameter in inches, ba is the basal area in square feet per acre, tpa is the trees per acre, and 0.005454154 is a constant.
In metric units:
$$D_q = \sqrt{ \frac{\frac{ba}{tpha}}{0.00007854}}$$
where: Dq is the Quadratic Mean Diameter in centimeters, ba is the basal area square meters per hectare, tpha is the trees per hectare, and 0.00007854 is a constant.
Example
- Imperial units
- ba = 80 ft2/ac
- tpa = 200
- unittype = "imperial"
- Answer = 8.56 in
- Metric units
- ba = 18.3 m2/ha
- tpha = 494.1
- unittype = "metric"
- Answer = 21.7 cm
Code
This code is stored in my Github.com\larsendr site. These are direct links to the raw code.
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