Stand dynamics and biomass distribution in clonal and mixed genotype Pinus taeda stands with contrasting crown attributes

The structure of even-aged forests is influenced by individual tree growth variation, leading to stand differentiation. It has been hypothesized that deployment of genetically uniform trees (i.e., clonal stands) could result in less within-stand variation. Additionally, the ideotype concept posits that crown characteristics may influence the competitive ability of genotypes. Few studies have compared clonal and non-clonal material in field studies, the effect of clonal deployment on stand dynamics, or ideotypes in the context of stand development. This study investigated the influence of crown attributes and plot genetic variability on competitive interactions and stand differentiation in loblolly pine. Results showed significant spacing and genotype effects, as well as significant spacing-by-genotype interactions for total tree height, DBH, and individual tree volume. Clone A and Clone B differed significantly in crown size and stem wood biomass when grown at narrow spacing, but not at wide spacing. Reduced allocation to branches in Clone B corresponded to greater height growth under narrow spacing. Uniformity and productivity were not affected by the degree of within-stand genetic variation.