Genetic and Environmental Factors Behind Foliar Chemistry of the Mature Mountain Birch Sanna Haviola & Seppo Neuvonen & Markus J. Rantala & Kari Saikkonen & Juha-Pekka Salminen & Irma Saloniemi & Shiyong Yang & Teija Ruuhola Received: 23 February 2012 / Revised: 28 April 2012 / Accepted: 3 May 2012 # Springer Science+Business Media, LLC 2012 Abstract Previous studies of mountain birch (Betula pubes- cens spp. czerepanovii) repeatedly have found differences between individual trees in herbivory-related traits, but rarely have yielded estimates of the additive genetic variation of these traits or of their relationship to habitat. We used thirty- year-old birch half-sibs in a northern common garden to estimate the effect of genetics and local microhabitat on resistance-related traits. Genetic estimates of foliar chemistry have been studied only rarely with trees as old as these. Moth performance (Epirrita autumnata), rust (Melampsoridium betulinum) incidence levels, and the general level of natural herbivory damage to individual trees were used as direct measures of birch resistance. Chemical resistance-related traits in plant chemistry included 15 individual phenolics, 16 amino acids, and phenoloxidase activities in the foliage. We also followed birch phenology and growth. Our results show that the genotype of the birch was the most important deter- minant of phenolic composition and phenoloxidase activity, but that amino acid levels were best explained by the microhabitat of the birch. We also found that the phenology of the birch had a high heritability, although its variation was low. Our results reveal rich genetic variation in birch chemistry. Keywords Microhabitat . Additive genetic variation . Heritability . Woody plant . Phenotypic correlation . Phenotypic plasticity . Insect outbreaks Introduction Long-living, “apparent” trees are especially vulnerable to herbivory (Feeny, 1976), as insect life cycles and potential population growth rates are faster than those of trees. Thus, insects should be able to adapt to the defensive chemistry of the trees. Nevertheless, plant-herbivore interaction models have shown that variance in plant quality has the potential to influence herbivore population dynamics (Shelton, 2004; S. Haviola (*) : M. J. Rantala : S. Yang Section of Ecology, Department of Biology, University of Turku, 20014 Turku, Finland e-mail: sanna.haviola@utu.fi S. Haviola Kevo Subarctic Research Institute, University of Turku, 20014 Turku, Finland S. Neuvonen The Finnish Forest Research Institute, PL 68, 80101 Joensuu, Finland K. Saikkonen Plant Production Research, MTT Agrifood Research Finland, 31600 Jokioinen, Finland J.-P. Salminen Laboratory of Organic Chemistry and Chemical Biology, Department of Chemistry, University of Turku, 20014 Turku, Finland I. Saloniemi Laboratory of Genetics, Department of Biology, University of Turku, 20014 Turku, Finland S. Yang Section of Ecology, College of Life Science, Anhui Normal University, Wuhu 241000, Anhui, China T. Ruuhola Department of Biology, University of Eastern Finland (UEF), 80101 Joensuu, Finland J Chem Ecol DOI 10.1007/s10886-012-0148-0