Growth and stem form quality of clonal Pinus taeda following fertilization in the Virginia PiedmontThis article is part of a larger document. View the larger document here.
Clonal forestry offers the opportunity to increase yields, enhance uniformity, and improve wood characteristics. Intensive silvicultural practices, including fertilization, will be required to capture the full growth potential of clonal plantations. However, variation in nutrient use efficiency that exists among clones could affect growth responses. Our research objective was to determine the range of growth response and stem form quality due to fertilization in clones of Pinus taeda. A split-plot experimental design was used, with the whole plots being 2 levels of fertilization (with or without) and the split-plot factor being 25 clones. Whole-plot treatments were blocked and replicated four times. Trees were planted in May 2003, with fertilizer applied in May 2004 and May 2006. Five years after planting, a repeated measures analysis showed fertilizer by time and clone by time interactions significantly affected volume. Although there were no fertilizer by clone interactions in this trial across all 25 clones, the response to fertilizer varied, with 40 percent of the clones showing a volume improvement at 3.5 years of <3 percent while 20 percent showed improvement >15 percent. Our results suggest that a screening technique for clonal response to silvicultural treatments such as fertilization may be necessary given the wide range of fertilizer responses found among clones in this field trial and the large numbers of clones being developed by forest industry.