Estimating Douglas Fir Height from Stump Diameter

DBH-Height Relationship for Douglas Fir

Research (Oregon State University) shows a 7.5-inch DBH Douglas fir typically reaches 50-55 feet tall at medium growth rates in western Oregon.

Reference Data

• OSU Research Contribution 25: Figure 2 correlates DBH to height.
• 7″ DBH ≈ 50-55 ft height (medium site index).
• Variability: ±15 ft based on site quality, competition, genetics.

Regression Models Exist But...

• Species-specific equations (e.g., Curtis, 1967; Hann & Scrivani, 1987).
• Require site index, age, stand density for accuracy.
• Stump-only measurement = high uncertainty.

Practical Next Steps

1. Contact Oregon Dept. of Forestry (ODF) for local forester assistance.
2. ODF contact: https://www.oregon.gov/ODF/contact_us.shtml
3. If legal/valuation context: hire Consulting Forester (ACF/SAF certified) for on-site appraisal.
4. Stump height (4″) suggests cutting was recent—may affect liability/timber trespass calculations.

Why Professional Help Matters

Tree valuation involves species, grade, volume, market, and legal context. A consultant provides defensible numbers; generic formulas don't.