Scots pine populations contain individuals with widely differing amounts and composition of monoterpenes and exist as one of two chemotypes: with or without Î"3-carene. We investigated the significance for ecological studies of two types of variation in monoterpenes: (1) the inherent variability in the concentration of monoterpenes or their relative amounts in needles of seedlings, saplings, and mature trees; and (2) phenological variation in developing needles. The relative composition of needle monoterpenes in 5-year-old saplings changed during the needle development period until the final composition was reached upon needle maturity. Changes in composition depended on chemotype. Needles of the "no-Î"3-carene" chemotype had higher absolute concentrations of α-pinene, β-pinene, camphene, and total monoterpenes than "Î"3-carene" chemotype. For the "Î"3-carene" chemotype, the relative concentration of Î"3-carene during the needle growing season and immediately after emergence of seedlings was higher compared to that reached at needle maturity. Repeated removal of single needles (at weekly intervals during growth) from 5-year-old saplings did not influence the composition of monoterpenes. Within a natural Scots pine dominated woodland, 18% of mature Scots pines (N = 574) belonged to the "no-Î"3-carene" chemotype. Chemotypic variation within populations means that the statistical power with which differences in monoterpene concentrations can be detected is lower when sampling from the whole population compared to sampling within chemotypes. Reduction of this background variation and accounting for chiral variation if present, would significantly aid efficiency, interpretation, and understanding of processes in chemical and ecological research. One method for achieving this is the screening of plants for chemotypes before the establishment of experiments or field sampling regimes. We present a summary of suitable analytical methods for needle tissue that facilitates this prior screening. © 2007 Springer Science+Business Media, LLC.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Evolutionary biology
Research Field:	Evolutionary biology not elsewhere classified
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Forestry
Objective Field:	Native forests
UTAS Author:	O'Reilly-Wapstra, JM (Professor Julianne O'Reilly-Wapstra)
ID Code:	50563
Year Published:	2007
Web of Science® Times Cited:	38
Deposited By:	Plant Science
Deposited On:	2007-08-01
Last Modified:	2009-11-06
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