Fixed plot
Use known plot area and DBH lists to calculate basal area per area and stem density.
Input
SettingsSettings
Result
--Basal area / area
—
Stem density
—
Average DBH (QMD)
—
QMD
Total tree count
—
Trees
Point count
—
Row results
Arithmetic mean DBH
—
Arithmetic mean DBH
Warnings
--
| Trees | Basal area | Stem density | Arithmetic mean DBH | QMD | |
|---|---|---|---|---|---|
| -- | |||||
Metode survei yang didukung
BAF angle gauge
Use in-tree DBH lists and BAF to estimate basal area per area and stem density from point samples.
Average DBH is QMD
The primary average DBH is QMD, or quadratic mean diameter. Arithmetic mean DBH is shown as a secondary check when tree-level diameters are present.
Contoh
Input / OutputCara menggunakan
- Switch the survey mode between fixed plot and BAF.
- Choose the unit system, DBH unit, and either plot area or BAF depending on the mode.
- Enter the DBH list for each plot or point. You can separate values with newlines, commas, semicolons, or spaces.
- Review basal area, stem density, and QMD, then use copy, CSV, JSON, share URL, or print when needed.
Frequently asked questions
Is average DBH the arithmetic mean?
The primary average shown by this tool is QMD. Arithmetic mean DBH is shown as a secondary check only when tree-level diameters are present.
Can BAF alone estimate stem density?
Yes. With DBH values entered, the tool estimates stem density from each in-tree's expansion factor.
Should DBH be measured at 1.3 m or 4.5 ft?
Either is fine as long as you use one consistent measurement standard for the values you enter. The tool does not auto-correct height standards.
Do you handle slope correction or boundary-tree rules?
No. The tool only aggregates the numbers after field tallying.
Can I share large row data through a URL?
Yes, but the URL can become long. Use JSON export and import for larger surveys.
Glosarium
DBH
Diameter at Breast Height. Tree diameter measured at breast height.
Basal area
The cross-sectional area of tree stems at breast height.
Stem density
The number of trees per unit area.
QMD
Quadratic Mean Diameter. An average DBH derived from basal area and stem density.
BAF
Basal Area Factor. The factor used in angle-gauge surveys.
Fixed plot
A tally method using a plot with a known area.
Rumus
tree basal area = π × (dbh / 2)^2
basal area per area = Σ tree basal area / sample area
stem density = tree count / sample area
QMD = sqrt(4 × basal area per area / (π × stem density))
BAF row basal area = in-tree count × BAF
BAF row stem density = Σ (BAF / tree basal area)
Catatan
- DBH measurement height standards vary by country and stand. Make sure all values were measured using the same standard.
- Follow your field tally rules for boundary trees when using BAF.
- QMD is the primary metric. It may not match arithmetic mean DBH.
- Do not put private stand names or trial-plot names into share URLs or notes.
- The result is a summary value, not the final basis for legal, certification, or management decisions.