Estimating Site Index for White and Black Oaks in Indiana From Soil and Topographical Factors

The standard site-curve method of determining site index has limited application in upland central hardwoods as many stands show signs of past suppression, or are uneven-aged, grazed, or periodically burned. Therefore, the soil-site method was used to relate height of trees in unsuppressed, even-aged stands to age and features of soil and topography. Site-index values for white and black oak in southern Indiana were then calculated from the derived relationships. Based on 154 site plots it was found that site index for white and black oak was strongly related to A-horizon thickness, slope position, silt content of the B1 horizon, clay content of the B horizon and material below this zone, and stone content of the B2 horizon. Slope aspect and slope shape are additional features that influence site index of white oak. Site tables based on these features were prepared to estimate site index of white and black oak on upland soils of southern Indiana. The principles are applicable elsewhere.