Biomass expansion factors and allometric equations in an age sequence for Japanese cedar (Cryptomeria japonica) in southern Korea

Biomass expansion factors (BEFs) were developed for an age sequence (<20, <30, <40, and <50 years old), and the allometric relationships for aboveground and belowground tree biomass components (stem wood, stem bark, branch, foliage, and root) were derived for Japanese cedar (Cryptomeria japonica). BEFs of tree components varied with age class, especially in the above and below 20-years-old classes (2.16 vs. 1.44). However, stem densities for different age classes were not significant (0.40). The developed allometric equations for the biomass components were significant when based on either a single variable [diameter at breast height (DBH) or DBH2 times stem height H (DBH2H)] or a combination of these variables (DBH and H). Ratios of root to shoot for different age classes ranged from 0.24 to 0.32, which were significant, and decreased with increasing age. Changes in tree biomass partitioning and allometry with age sequence must be considered to accurately estimate forest carbon stocks.