Effects of nutrient amendments and genotype on stand productivity and crown characteristics in loblolly pine (Pinus taeda L.)

by 1974- Handest, Joshua A.

Handest, Joshua A. Effects of Nutrient Amendments and Genotype on Stand Productivity and Crown Characteristics in Loblolly Pine (Pinus taeda L.) (Under the direction of H. Lee Allen and Steven E. McKeand). Two provenances of loblolly pine, with five open-pollinated families from each were analyzed for differences in height, volume, leaf area, and various crown characteristics. Families from the North Carolina and South Carolina Coastal Plain (ACP) and from the “Lost-Pines” area of Texas (LPT) were included in the study. In addition to studying potential genetic variation, half of the plots received fertilization treatments so that potential nutrient and genotype x environment (GxE) interactions could be assessed. The stands were established in 1993 and height was measured annually until year 3 when both height and diameter at breast height were measured. Leaf area measurements were made in 1999 using the LI-CORE LAI-2000 PCA and destructive and non-destructive sampling of individual branches was done to estimate the crown characteristics Nutrient additions starting at stand establishment resulted in large gains in juvenile development in height, volume, leaf area, and growth efficiency. Fertilization also dramatically increased foliage and branch biomass at all crown levels, and also contributes to an early shift of foliage from the lower crown to the middle. This is most likely due to early canopy closure. The Atlantic Coastal Plain provenance consistently outperformed the Lost Pine Texas provenance in height, volume, and growth efficiency. The ACP provenance had more foliage, predominately in the middle crown than the LPT provenance, which may explain some of the productivity differences. There was a significant amount of variation in height, volume, leaf area, and growth efficiency between the families of both provenances. Both the vertical distribution and quantity of foliage in the ACP families may explain some of the variation in volume growth and growth efficiency, though neither show enough of a direct correlation to explain all of it. The crown characteristics studied seem to indicate that distribution of foliage itself is more important in explaining differences among the LPT families. Effects of Nutrient Amendments and Genotype on Stand Productivity and Crown Characteristics in Loblolly Pine (Pinus taeda L.) by