Variation in biomass distribution and nutrient content in loblolly pine (Pinus taeda L.) clones having contrasting crown architecture and growth efficiency

• Three Pinus taeda clones differed in biomass allocation to bark, branches and foliage.
• Allocation of biomass to stem wood was similar among the three clones.
• The narrow crowned clone produced more stem wood per unit foliage nutrient content.
• The narrow crowned clone characteristics were consistent with a crop ideotype.

Loblolly pine (Pinus taeda L.) is well adapted across an extensive range of sites, is responsive to silvicultural treatments, and has undergone genetic improvement through traditional tree breeding programs, with selection based primarily on rapid growth and disease resistance. Loblolly pine clones with contrasting crown architecture provide an opportunity to better understand the mechanistic relationships among stem growth, biomass partitioning, and component nutrient content. We assessed inventory data from four clones which exhibited a range of crown widths. Using a subset of three clones, we measured crown sizes, crown volume, biomass allocated to components (foliage, branches, stemwood and bark), and component nutrient concentration and content to assess variation in allocation and growth efficiency. Clonal variation in biomass distribution patterns helped explain variation in growth efficiency between the narrow crown clone (ARB-1) and wide crown clone (ARB-4). Clone ARB-1 was more efficient at producing stem biomass increment per unit foliar biomass and unit foliar nutrient content than clone ARB-4; this was consistent with the concept of a crop ideotype. This study provides new information useful for improving our understanding of the relationships among crown structure, biomass distribution patterns, growth efficiency, and tree productivity, and may help guide clonal tree population management.