Allometry Varies among 6-Year-Old Pinus taeda (L.) Clones in the Virginia Piedmont

Clonal forestry is becoming a reality in the southeastern United States owing to recent improvements in somatic embryogenesis for Pinus taeda (L.). Differences in aboveground and belowground carbon allocation between individual genotypes could have significant implications for productivity and carbon sequestration and cycling in clonal plantations. We assessed biomass partitioning, allometry, coarse root morphology, and crown size of 10 P. taeda clones at age 6 in the Virginia Piedmont in control and operationally fertilized plots. Clonal effects were observed for biomass partitioning to foliar, branch, stem, taproot, and lateral root fractions; allometric relationships including root/shoot, stem/foliage, branch/foliage, and stem/taproot ratios; root morphology; and crown size. Clonal differences in biomass partitioning were the result of both differences in allometry and differences in growth rates. Growth efficiency (stem/foliage ratio) showed a twofold difference among the two most disparate clones even after standardizing for different growth rates. Clone-by-fertilizer interactions were observed for total, aboveground, and belowground biomass and for root depth sampled up to 1 m. Differences in partitioning and allometry were not clearly tied to tree or stem growth rates, indicating that there may be opportunities to select and deploy clones with rapid stem volume growth rates that have biomass partitioning patterns tailored to various precision-silviculture applications. FOR. SCI. 59(1):50-62.