Challenges in estimating forest biomass: use of allometric equations for three boreal tree species

Regionally-fitted allometric equations for individual trees and root-to-shoot ratio values are normally used to estimate local above- and belowground forest biomass, respectively. However, uncertainties arising from such applications are poorly understood. We developed both above- and belowground biomass equations using destructive sampling for three dominant upland boreal tree species in northwestern Alberta, Canada. Compared to our equations, the diameter-based national equations derived for use across Canada underestimated aboveground biomass for Picea glauca, but gave reasonable estimates for Populus balsamifera and P. tremuloides. The national equations based on both tree diameter and height overestimated aboveground biomass for the Populus species, but underestimated it for Picea glauca in our study area. The root-to-shoot ratio approach proposed by IPCC overestimated belowground biomass by 16â 41% depending on forest cover type in comparison to our values estimated directly on site, with the greatest bias in deciduous-dominated stands. When the general allometric equations for aboveground and the root-to-shoot ratio for belowground biomass were combined to estimate stand biomass, overestimation could be as high as 18% in our study area. Our study supports development of improved regional allometric equations for more accurate local-scale estimations. Incorporating intraspecific variation of important traits like tree taper may be especially helpful.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author