The extractive content of inner and outer heartwood of in total 9 Scots pine trees from different stands in the Kongsberg area was measured by accelerated successive extraction (ASE). Compounds or substance classes were identified using gas chromatography coupled with mass spectrometry (GC-MS). Besides, some measurements were carried out on cellular level by means of UV micro-spectrophotometry (UMSP).
The climate during growth does not influence the extractive content significantly, when taking into account both inner and outer heartwood. The slenderness coefficient however, has a large impact on the extractive content of the outer heartwood. More slender stems are characterized by a lower extractive content. Beside this a slight trend was found for total amount of extractives of the outer heartwood and altitude, where extractive content tended to increase with increasing altitude.
The evaluation of mass spectra of petroleum ether extracts in combination with a NIST library search shows the presence of α-pinene and carene as well as terpinene and cadinene derivatives for both inner and outer heartwood. Since these substance groups were found in lower quantities in the inner heartwood, a lower durability due to a reduced hydrophobicity of the inner heartwood compared to the outer is to be expected.
UMSP graphs indicate that there is no significant difference within the lignin content between the three heartwood origins. This outcome confirms ASE results that the colour of the heartwoods depends predominantly on the extractive content.
Keywords: extractive content, climate, Norwegian forest stands, Scots pine heartwood
Authors
Zimmer K.
Norwegian Forest and Landscape Institute, Ås, Norway
Melcher E.
Thünen Institute of Wood Research, Hamburg, Germany
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