Forest Inventory - Timber Metrics

Timber Metrics

The amount of standing timber that a forest contains is determined from '

• Basal area - defines the area of a given section of land that is occupied by the cross-section of tree trunks and stems at their base
• Diameter at breast height (DBH) - measurement of a tree's girth standardized at 1.3 meters (about 4.5 feet) above the ground
• Form factor - the shape of the tree, based on recorded trees and commonly then given for calculating tree volumes for a given species. It is usually related to DBH or age class. It is distinct from taper. So it can be Cone or paraboloid for example.
• Girard form class - an expression of tree taper calculated as the ratio of diameter inside the bark at 16 feet above ground to the to that outside bark at DBH, primary expression of tree form used in the United States
• Quadratic mean diameter - diameter of the tree that coordinates to the stand's basal area
• Site index - a species specific measure of site productivity and management options, reported as the height of dominant and co-dominant trees (site trees)in a stand at a base age such as 25, 50 and 100 years
• Tree taper - the degree to which a tree's stem or bole decreases in diameter as a function of height above ground. So it can be sharp or gradual.