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Site index (SI) is a measurement commonly used by foresters to describe the productivity of a site. Typically this measurement is used to describe sites growing well-stocked even-aged forests. Site index is the average height of the dominant1 and codominant2 trees on the site, at a given age (base age). Typically, the base age for hardwoods and white pine in Virginia is 50 years, while the base age for loblolly pine is 25 years. For example, a SI of 75, base age 50, means that the average height of the dominant and codominant trees on a site will be 75 feet when they are 50 years old (SI50=75). The higher the SI, the higher the site productivity (trees will grow faster than on a site with a lower SI).
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Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Interim Administrator, 1890 Extension Program, Virginia State University, Petersburg.
December 3, 2014