PS 71-136 - Seasonal growth patterns of young longleaf pine

Thursday, August 6, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
John C. Gilbert1, Ralph S. Meldahl2, John S. Kush3, William D. Boyer4 and Dean H. Gjerstad2, (1)Longleaf Pine Stand Dynamics Laboratory, School Forestry and Wildlife Science, Auburn University, Auburn University, AL, (2)Longleaf Pine Stand Dynamics Laboratory, School of Forestry and Wildlife Sciences, Auburn University, Auburn University, AL, (3)Longleaf Pine Stand Dynamics Laboratory, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, (4)G.W. Andrews Forestry Sciences Laboratory, USDA Forest Service, Auburn, AL
Background/Question/Methods Since the 1930s, scientists have been studying the growth patterns of longleaf pine (Pinus palustris Mill.) and examining relationships between growth and the environment. Studies have examined height and diameter growth of longleaf pine at various ages, but few have concentrated on young longleaf pine. For those studies examining the growth of young longleaf pine, measurements of seasonal growth and individual flushes have produced conflicting observations. To further explore the growth patterns of young longleaf pine, this study was installed on a middle Coastal Plain site located on the Escambia Experimental Forest in southern Alabama. Forty young longleaf pine trees ranging from 1 to 1.5 meters in height were measured during 1969 and 1970. The trees were evenly divided between two soil types, and a shading treatment was applied during the first growing season. Height and diameter measurements were recorded for the trees during both the growing and dormant seasons. The length of the terminal bud was recorded prior to each growing season, and all growth flushes were recorded separately. Percent foliage and needle lengths were also recorded during the second year. 
Results/Conclusions Both height and diameter growth displayed cyclic patterns during the two years. The growing season began in March and tended to peak in April or May. Throughout the growing season, height growth occurred in flushes with continuous growth of up to two flushes at one time. During both years, over 30% of total height growth occurred in the month of April and in the first flush of the growing season. Height growth declined from this point on, and 90% of the year’s growth was completed by the end of August before ceasing in early November. However, 90% of the year’s total diameter growth was completed by September or October for both years. Regression and correlation analyses were used to examine relationships between bud lengths and individual flushes. The effects of the shading treatment and soil type differences were also tested for both height and diameter growth.
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