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The monoterpenes from needles of 47 adult trees of Picea abies (L.) Karst., grown under natural conditions, were studied to get information about the tree-to-tree variation within three adjacent locations and the differences between the locations. For the absolute amounts of the monoterpenes the tree-to-tree variation ranged between 50% and 70%, expressed as the relative coefficient of variation. All three populations showed similar variations. When looking for different genotypes, at each location two groups of trees were observed, which were characterized by the ratio of myrcene to limonene.

Summary. The extractable monoterpenes from needles of two groups of trees -4-year-old clonal and 20-year-old wild trees -were studied with respect to the influence of individual constitution, needle age, whorl position, and position on branch. Leaf terpene amounts from clonal trees are significantly affected by age and position of the whorl, whereas position on the branch is of minor importance. Developing needles of clonal trees are most strongly affected by age and whorl position and they differ markedly from mature needles in quantitative terpene composition. Wild trees exhibit a very high variation from tree to tree, which obscures the influence of needle age and position. For this reason meaningful tree leaf terpene data will only be derived if large samples of needles of different ages are collected from distinct positions. When comparing different trees, needles should be selected that not only have the same state of development, but also originate from identical positions and have been subjected to the same light treatment.

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