Predicting Root Biomass of Burned and Unburned White Oak Advance Reproduction from Diameter and Height

The size, especially the root size, of advance oak (Quercus spp.) reproduction provides the best indication of the growth potential afer release or top-kill. This study examined the relationship between the size of the root system and various diameterheight measurements for small (<60 cm) white oak (Q. alba L.) seedlings. Diameters measured at the top of the litter and humus luyers and at the root collar were tested for their ability to predict root biomass on burned and unburned sites. Despite their close physical proximiiy, separate equations were required for burned and unburned sites when predicting root biomass from diameters measured at the humus and root collar locations, as well as height and diameterheight combinations. On burned sites, all diameter measures were good predictors, accounting for 75 to 86% of the total variance of root biomass. On the unburned site, the best predictor was the diameter measured at the root collar, accounting for 85% of the total variance of root biomass. Diameter at the litter level accounted for only 55% of the total variance of root biomass whereas diameter at the top of the humus layer accounted for 53%. When dealing with stands of unknown disturbance history, the diameter measured at the root collar should be used to predict root biomuss for small seedlings. South. J. Appl. For. 30(1):40-45.