Dendrochronologia 33 (2015) 54–60 Contents lists available at ScienceDirect Dendrochronologia j ourna l h o mepa ge: www.elsevier.com/locate/dendro ORIGINAL ARTICLE Effects of experimental stem burial on radial growth and wood anatomy of pedunculate oak Paul Copini a,∗ , Mathieu Decuyper a , Ute Sass-Klaassen a , Holger Gärtner b , Frits Mohren a , Jan den Ouden a a Wageningen University, Forest Ecology and Forest Management Group, P.O. Box 47, 6700 AA Wageningen, The Netherlands b Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland a r t i c l e i n f o Article history: Received 21 September 2014 Accepted 15 December 2014 Keywords: Dendrogeomorphology Drift sand Growth response Quercus robur Wood anatomy a b s t r a c t In dendrogeomorphology, abrupt changes in wood anatomy are frequently used to date the exact year of burial and exposure events. However, few studies have addressed the precision and underlying mech- anisms of these changes. In a field experiment, performed in a drift-sand area in the Netherlands, we buried the stems of mature pedunculate oak trees (Quercus robur L.) up to a height of 50 cm and ana- lysed the responses in ring width and earlywood-vessel characteristics, while monitoring the course of temperature above and below the soil surface. After 3 years of stem burial, we found no significant differences in ring width and earlywood-vessel characteristics between control and buried trees both above and below the burial level. Burial however strongly reduced temperature amplitude and the occurrence of sub-zero temperatures around the buried stems. All buried trees formed epitropic roots that grew upward into the new sediment layer, but no adventitious roots were formed on the buried stems. Irrespective of the burial treatments, we found that the mean ring width was largest at the original stem base and lowest at breast height. In contrast, vessel sizes were significantly larger at breast height compared with the stem base. Differences in vessel density barely differed between years and heights. In our field experiment on mature pedunculate oak trees, the burial of stems by 50 cm of drift sand did not induce any local growth suppression or detectable changes in wood anatomy. As wood-anatomical changes in response to burial have previously been reported for trees that had formed adventitious roots, we stress the role of adventitious-root formation as a possible trigger behind the local changes in wood anatomy, reflecting a functional change of a buried stem towards a root. Based on our field experiment, it seems unlikely that years of shallow or moderate burial events (≤50 cm) can be reconstructed using the wood structure of buried stems. As epitropic roots develop quickly after burial, dating such roots may potentially yield better estimates of burial events. Further research on the relation between adventitious root and changes in stem anatomy is needed to ascertain the precision of dating sand-burial events using tree rings. © 2015 Elsevier GmbH. All rights reserved. Introduction Dendrogeomorphology is a powerful tool to reconstruct geo- morphic processes with high temporal resolution (Alestalo, 1971; Stoffel et al., 2010). This method is frequently used to ascer- tain erosion and accumulation rates or dynamics of sediment transport in many different ecosystems (e.g. Gärtner et al., 2001; Bodoque et al., 2005; Den Ouden et al., 2007; Stoffel et al., 2013). ∗ Corresponding author. Tel.: +31 317 486355; fax: +31 317 486360. E-mail address: Paul.copini@wur.nl (P. Copini). Transitions in ring width and vessel or tracheid-lumen size caused by burial or exposure have been used to date the exact year when such events occurred (Cournoyer and Bégin, 1992; Gärtner et al., 2001; Friedman et al., 2005; Stoffel et al., 2013). Normally, stems react to burial with reduced growth, whereas exposure of roots leads to the opposite (Fayle, 1968; Marin and Filion, 1992; Friedman et al., 2005; Matisons and Br ¯ umelis, 2008). In conifers, exposed roots may develop tracheids that are reduced by 50% in the lumen area, whereas stems show a 50% increase in tracheid lumen after burial (Marin and Filion, 1992; Cournoyer and Filion, 1994; Gärtner et al., 2001). In broadleaved species, the response differs between diffuse-porous and ring-porous trees. Whereas http://dx.doi.org/10.1016/j.dendro.2014.12.001 1125-7865/© 2015 Elsevier GmbH. All rights reserved.