What is a site index?

What is a site index?

• A. A measure of site quality based on the average height of dominant and co-dominant trees of an even-aged stand at a given age.
• B. The total site wood volume.
• C. The soil pH range.
• D. The number of trees per hectare.

Answer: (C)

Site index measures how productive a forest site is by looking at how tall the dominant and codominant trees are at a standard reference age for a given species. The idea is that taller potential height at that reference age reflects better growing conditions on the site, such as soil depth, moisture, and nutrients. It’s derived from measuring those tall trees in a stand and comparing them to species-specific growth curves to yield a single index value. This differs from measures like total wood volume, soil chemical properties (like pH), or tree density (trees per hectare), which are about volume output, soil chemistry, or stand stocking rather than the site’s growth potential.

Site index measures how productive a forest site is by looking at how tall the dominant and codominant trees are at a standard reference age for a given species. The idea is that taller potential height at that reference age reflects better growing conditions on the site, such as soil depth, moisture, and nutrients. It’s derived from measuring those tall trees in a stand and comparing them to species-specific growth curves to yield a single index value. This differs from measures like total wood volume, soil chemical properties (like pH), or tree density (trees per hectare), which are about volume output, soil chemistry, or stand stocking rather than the site’s growth potential.