Validation and refinement of allometric equations for roots of northern hardwoods

The allometric equations developed by Whittaker et al. (1974) at the Hubbard Brook Experimental Forest have been used to estimate biomass and productivity in northern hardwood forest systems for over three decades. Few other species-specific allometric estimates of belowground biomass are available, because of the difficulty of collecting the data, and such equations are rarely validated. Using previously unpublished data from Whittaker’s sampling effort, we extended the equations to predict the root crown and lateral root components for the three dominant species of the northern hardwood forest: American beech, yellow birch and sugar maple. We also refined the allometric models by eliminating the use of very small trees for which the original data were unreliable. We validated these new models of the relationship of tree diameter to the mass of root crowns and lateral roots using root mass data collected from 12 northern hardwood stands of varying age in central New Hampshire. These models provide accurate estimates of lateral roots (< 10 cm diameter) in northern hardwood stands > 20 years old (mean error 24-32%). For the younger stands we studied, allometric equations substantially underestimated observed root biomass (mean error > 60%), presumably due to remnant mature root systems from harvested trees supporting young root-sprouted trees. __________________________ This reformatted accepted manuscript is made available by the authors, in accordance with the author rights policy of NRC Research Press. The formatted final version is available from the publisher at http://dx.doi.org/10.1139/X07-032 This document should be cited as: Vadeboncoeur, M.A., S.P. Hamburg, and R.D. Yanai. 2007. Validation and refinement of allometric equations for roots of northern hardwoods. Canadian Journal of Forest Research 37(9): 1777–1783. Vadeboncoeur et al. 2007 Validation and refinement of root allometric equations [postprint]