Sessile Oak: A Tree for All Seasons
Hardtle, W., Niemeyer, T., Assmann, T., Aulinger, A., Fichtner, A., Lang, A., Leuschner, C., Neuwirth, B., Pfister, L., Quante, M., Ries, C., Schuldt, A. and von Oheimb, G. 2013. Climatic responses of tree-ring width and δ13C signatures of sessile oak (Quercus petraea Liebl.) on soils with contrasting water supply. Plant Ecology 214: 1147-1156.
In the words of the thirteen researchers, results indicated that "all stands showed a (more or less) continuous increase in BAI over 160 years," which finding "contradicts the sigmoid tree growth model according to which growth should plateau (and decline) with progressing tree ageing." However, they say their finding "is not unique" in this regard, and that it is "in agreement with other studies documenting long-term trends in BAI for other tree species during the last century," citing Johnson and Abrams (2009) and Kint et al. (2012). And they go on to suggest that "this trend is mainly influenced by enhanced CO2 levels," and that the trees responded to this stimulus "either directly with increasing carbon sequestration or indirectly through CO2 effects on intrinsic water use efficiency," citing Battipaglia et al. (2013). So in summation, they write that "Q. petraea showed little climate sensitivity and was able to recover from climate extreme events even at tree-ages beyond 200 years."
Hardtle et al. conclude that their findings "indicate the importance of Q. petraea as an adaptive tree species in forest ecosystems of Central Europe under shifting climatic conditions," while the similar findings of the others they cite, who worked with still other tree species, suggest that it was the increase in the air's CO2 concentration that enabled the various studied species to positively respond as observed.
Battipaglia, G., Saurer, M., Cherubini, P., Calfapietra, C., McCarthy, H.R., Norby, R.J. and Cotrufo, M.F. 2013. Elevated CO2 increases tree-level intrinsic water use efficiency: insights from carbon and oxygen isotope analyses in tree rings across three forest FACE sites. New Phytologist 197: 544-554.
Ellenberg, H. and Leuschner, C. 2010. Vegetation Mitteleuropas mit den Alpen. Ulmer, Stuttgart, Germany.
Johnson, S.E. and Abrams, M.D. 2009. Basal area increment trends across age classes for two long-lived tree species in the Eastern U.S. In: Kaczka, R., Malik, I., Owczarek, P., Gartner, H., Helle, G., and Heinrich, I. (Eds.). Tree Rings in Archaeology, Climatology and Ecology. Volume 7. GFZ Potsdam, Scientific Technical Report 09/03, pp. 127-134.
Kint, V., Aertsen, W., Campioli, M., Vansteenkiste, D., Delcloo, A. and Muys, B. 2012. Radial growth change to altered regional climate and air quality in the period 1901-2008. Climatic Change 115: 343-363.
Weigl, M., Grabner, M., Helle, G., Schleser, G.H. and Wimmer, R. 2008. Characteristics of radial growth and stable isotopes in a single oak tree to be used in climate studies. Science of the Total Environment 393: 1554-161.