title: High-resolution densitometry and elemental analysis of tropical wood.
abstract: CONCLUSIONS
  Understanding the mobility and distribution of chemical elements in wood is necessary to apply dendrochemistry. Crystals are likely stable and could be used to analyze changes in nutrient supply.
  Dendrochemistry uses the variation in wood chemical composition to infer about past environmental conditions and possible effects on tree growth. Elemental or isotopic variation might also help to identify annual growth where tree rings are anatomically not distinct. However, most elements are-to a certain degree-mobile within wood and may be related to anatomical structures. Therefore, understanding what affects elemental distribution is important to make use of and critically assess the potential of dendrochemistry. We studied the variation of wood density and elements at high spatial resolution in wood of six species with anatomically distinct to rather indistinct tree rings from a Thai monsoon forest. Many elements had a higher concentration in parenchyma than in fiber cells, and the co-variation of elements differed strongly between elements and also between species. Strong wood density changes along the ring boundary were found only inMelia azedarach. In all species, the X-ray images showed crystals. EDX spectra showed that these consist of calcium or silicon (inChukrasia tabularis) as major elemental components. A high concentration of heavy metals (Fe, Cu and Zn) was found inVitex peduncularis. We conclude that at least for the species studied the radial variation of elemental concentration is unlikely to reveal annual rings that anatomy could not. However, if elements in crystals are more stable than in cell walls or living protoplasts, analyzing the distribution of elements present in crystals may show environmental conditions that, in turn, influence crystal formation and are little known.
authors.affiliation: Institute of Botany, University of Natural Resources and Life Sciences Vienna, Gregor Mendel Strasse 33, 1180 Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Hietz
authors.affiliation: Division of Analytical Chemistry, Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Monika
authors.initials: M
authors.lastname: Horsky
authors.affiliation: Division of Analytical Chemistry, Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Prohaska
authors.affiliation: Core Facility Cell Imaging and Ultrastructure Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Lang
authors.affiliation: Institute of Wood Science and Technology, University of Natural Resources and Life Sciences Vienna, Konrad Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Grabner
keywords: Crystals; Dendrochemistry; Tropical wood; Wood anatomy; Wood chemical composition