Scaling a standing tree primarily involves measuring its dimensions to estimate the volume of usable wood it contains. This process is crucial for forestry, timber sales, and ecological assessments. Key measurements typically include the tree's diameter and merchantable height.
Essential Measurements for Scaling
To effectively scale a standing tree and estimate its timber volume, two fundamental measurements are required:
- Diameter: This is typically measured at breast height (DBH).
- Height: This refers to the merchantable height (the height up to which the tree can be used for timber) or total height.
Using these measurements along with regional volume tables or formulas allows foresters to calculate the estimated volume, often expressed in board feet, cubic feet, or cords.
Measuring Diameter at Breast Height (DBH)
Diameter at Breast Height (DBH) is a standard measurement taken at 4.5 feet (1.37 meters) above the ground on the uphill side of the tree. It's a critical input for most tree volume calculations. The provided reference details a common method using a specialized scale stick:
To measure DBH, stand squarely in front of the tree and hold the scale stick 25 inches from your eye in a horizontal position against the tree at 4½ feet above the ground. Shift the stick right or left until the zero end of the stick coincides with the left edge of the tree trunk. The point where the right edge of the trunk aligns with the numbers on the stick indicates the tree's diameter.
Here's a breakdown of the steps:
- Position Yourself: Stand directly in front of the tree.
- Locate DBH Height: Identify the point 4.5 feet (1.37 meters) above the ground on the uphill side of the tree.
- Hold the Stick: Hold the scale stick horizontally at this 4.5-foot height, keeping it 25 inches away from your eye.
- Align the Zero: Move the stick left or right until the 'zero' end of the stick lines up perfectly with the left edge of the tree trunk.
- Read the Diameter: Without moving your head or the stick from the 25-inch distance, look at the right edge of the tree trunk. The number on the scale stick that aligns with the right edge is the tree's DBH in inches.
Why is DBH Important?
DBH is a consistent and easily measurable point that provides a good representation of the tree's overall stem size. Combined with height, it allows for reliable volume estimation using established forestry tables and equations.
Other Aspects of Scaling
While diameter is key, scaling a standing tree also requires measuring height. This is often done using instruments like clinometers or hypsometers, which measure angles to the top and base of the merchantable portion of the tree from a known distance.
Once both diameter and height are measured, foresters use species-specific volume tables or specialized software to estimate the volume of lumber or wood products the tree could yield.
| Measurement | Standard Method | Purpose |
|---|---|---|
| Diameter (DBH) | Scale stick, diameter tape, calipers | Estimates stem size/girth |
| Height | Clinometer, hypsometer, height pole | Estimates usable length of stem |
| Form/Taper | Visual assessment, form class sticks (less common) | Adjusts volume estimate |
Scaling standing trees is a fundamental skill in forestry, enabling resource managers to inventory timber resources accurately and make informed decisions about forest management and harvest.
