Trees (2004) 18:230–236 DOI 10.1007/s00468-003-0300-0 ORIGINAL ARTICLE Notburga Gierlinger · Dominique Jacques · Manfred Schwanninger · Rupert Wimmer · Luc E. Pâques Heartwood extractives and lignin content of different larch species (Larix sp.) and relationships to brown-rot decay-resistance Received: 21 May 2003 / Accepted: 1 September 2003 / Published online: 30 September 2003  Springer-Verlag 2003 Abstract The extractive content of lignin and the brown- rot decay-resistance against Coniophora puteana and Poria placenta were studied in larch heartwood from different species and origin (Larix decidua var. decidua, L. decidua var. sudetica, L. kaempferi , L.  eurolepis). The study material consisted of 106 trees from a 39-year old provenance trial in France. The hot-water-soluble extractives were very variable (from5.66% to 20.50% of dry weight), but there was no significant variation between the investigated species and origins. In contrast, acetone extractives, the total amount of phenolics and lignin showed significant differences. The concentration of phenolics and lignin was significantly higher in L. kaempferi and in L.  eurolepis than in L. decidua. The total phenolics content was strongly correlated with decay-resistance in all investigated larch origins. A higher concentration of phenolics goes hand in hand with higher decay resistance and phenolics might therefore be a promising parameter to rapidly evaluate the level of decay-resistance in larch. Keywords European larch · Japanese larch · Hybrid larch · Heartwood extractives · Phenolics Introduction The genus Larix encompasses ten species that are widely distributed across the cooler regions of the northern hemisphere. In Europe, the natural habitat of Larix decidua Mill. (European larch) is scattered and repre- sented in various geographic races (subspecies) and ecotypes, which exhibit marked differences in growth rates and other tree characteristics (Schober 1985). Outside its native mountainous range, L. decidua is used for reforestation in lowlands, together with Japanese larch [L. kaempferi (Lamb.) Carr.] and hybrids between Euro- pean and Japanese larch (L. eurolepis Henry), because of their fast growth and high quality timber. Larch wood is usually valued for its good mechanical properties, its appealing colour and texture and also for the high natural durability of its heartwood (Knuchel 1954). Natural durability, or alternatively decay resistance, is defined as the ability of wood to resist biological degradation (Eaton and Hale 1993). Brown-rot decay is a common and very destructive type of decay of sawn softwoods. Brown-rot fungi utilize the cellulose and hemicelluloses of the cell wall, leaving the lignin essentially undigested, albeit modified by demethylation and oxidation (Green and Highley 1997). As a conse- quence the attacked wood darkens, shrinks, and breaks into brick-shaped pieces, leading to rapid structural failure. The heartwood, the dead inner core of the trunk, of larch is darker coloured, has more extractives deposited and exhibits higher durability. Heartwood amount is higher in Japanese larch than European larch but the latter shows a high variability between origins (Pâques 2001). Heartwood extractives are formed in situ at the sapwood- heartwood boundary from translocated carbohydrates or lipid substrates that infiltrate the cell walls (Saranpää and Piispanen 1994; Hillinger et al. 1996; Magel 2000; N. Gierlinger ( ) ) · R. Wimmer Institute of Botany, BOKU University of Natural Resources and Applied Life Sciences, Gregor-Mendelstrasse 33, 1180 Vienna, Austria e-mail: ngierlin@edv1.boku.ac.at Tel.: +43-1-476543197 Fax: +43-1-476543180 D. Jacques Centre de Recherche de la Nature des ForÞts et du Bois, Avenue MarØchal Juin 23, 5030 Gembloux, Belgium M. Schwanninger Institute of Chemistry, BOKU—University of Natural Resources and Applied Life Sciences, Muthgasse 18, 1190 Vienna, Austria L. E. Pâques UnitØ d’AmØlioration de GØnØtique et de Physiologie des Arbres forestiers, INRA, 45166 Olivet Cedex, France