Dominance and Stand Structure Analyses of a GXE Interaction Trial

Intra-specific competition of loblolly pine (Pinus taeda) is a key factor for individual tree development. Liu and Burkhart (1994) indicated that at the seedling stage environmental gradients dominate on tree growth, where intraspecific competition dominate later stages of the stand. However, little information has been provided on how genetic material and intensive silviculture interactions affect individual tree and stand performance. In addition, tree breeders have always been interested in early selection of future outstanding individual “dominant trees ” to obtain maximum economic benefits and productivity of future stands (Bridgwater et al., 1985; Li et al., 1991). Our objective was to analyze how contrasting genotypes of loblolly pine, under contrasting nutrition treatments, differ in dominance and stand structure from planting until 8 years of age. METHODS At SETRES2 seedlings from five open-pollinated families (FAM) each of Atlantic Coastal Plain (ACP) and Lost Pines of Texas (LPT) provenances (PROV), were planted at 1.5m x 2m in 1993 and received two nutritional treatments (TRT) (CTRL=no fertilization vs. FERT=continuous fertilization) in a split-split plot layout. After remova