X-ray based tree ring analyses

Sammanfattning: In this thesis, two x-ray based dendro-analyses (batch-wise microdensitometry and energy dispersive x-ray fluorescence (EDXRF)) and the conditions under which these methods could be used on the two typical boreal conifers Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) were evaluated. For density measurements using batch scanning x-ray densitometry, sample preparation and density calibration are vital to acquire high resolution and precision in densitometric measurements. Thickness and alignment should be adapted to give optimal resolution without loss of precision. Samples should be extracted to remove resins before wood density measurements. Ca, Mn, Fe, and Sr and in most cases K and Zn could thus be measured in an efficient way using EDXRF. Significant differences in concentrations between tree rings were found for all of these elements except Sr, indicating that tree ring concentrations of these elements could be correlated to changes in the tree environment. For Mn a correlation between soil pH and Mn concentration in tree rings was found. Other correlations between tree ring element concentration and tree environmental factors were also found. For most elements in tree-rings of Scots pine and Norway spruce it seems that the concentration is due to environmental conditions during the year the tree-ring was developed and several years afterwards. It is concluded that microdensitometry and EDXRF analyses on increment cores are cost-efficient and nondestructive analyses of wood properties. Batch-wise, x-ray based dendrochemical analysis provides opportunities for more property-based use of wood raw material and for environmental monitoring.