Stockholm tree ring laboratory

Welcome to the Stockholm Tree Ring Laboratory


Tree Ring Laboratory

Our research focuses on reconstructing the temporal and spatial variability of past climate by using multi-parameter tree-ring analysis. The method uses the unique and precisely dated annual growth patterns in trees to extract information of past environmental change and relies on dendrochronology, which is the scientific method of dating old wood based on the analysis of patterns of tree rings. There are many subfields and applications within dendrochronology. In archeology, dendrochronology is a well-established dating method, used for example for dating buildings and various wooden artifacts. In paleoecology, past ecological changes can be studied with the help of tree-ring derived growth patterns of vegetation. Dendroclim atological studies aim to understand how and when climate changes in the past occurred by analyzing various ring width parameters, such as ring width or the maximum latewood density (MXD).

Tree rings are wider when environmental conditions favor growth and narrower when conditions are harsh. Other properties of the annual rings, such as MXD, have been shown to be better proxies (at least for temperature) than simple the ring width. By combining multiple tree-ring proxies and sometimes also other climate proxy records, we try to estimate past local and regional climates back in time. In many parts of the world, wood is decomposed very slowly in oxygen poor environments like lakes and bogs. In such anaerobic environments wood material can be preserved for several thousands of years. In Scandinavia, two 7000 years long chronologies exist, which are built by so-called subfossil wood from lakes.


Laboratory instrumentation

The Stockholm Tree-Ring Laboratory is equipped with an ITRAX multiscanner manufactured by Cox Analytical Systems (, which enables us to analyze and produce high-quality density (MXD) data. To avoid the influence of humidity and temperature in the lab that would affect the density measurements, the environmental conditions in the lab are strictly controlled. The laboratory uses Dendrocut twin-bladed saw from Walesch Electronic.

The ITRAX machine is equipped with an EDXRF (energy dispersive X-ray fluorescence) sensor that can be used for identifying elemental signals in tree-rings, which may, for example, occur in response to volcanic eruptions and, especially, anthropogenic pollution. The atoms in the tree-samples are excited by X-Rays emitted from an X-Ray tube which enables analysis of trace elements and in turn trace environmental changes. 

We perform MXD and XRF analyzes both in conjunction with research collaborations and commercial service. Please contact Björn Gunnarson for further information regarding analysis costs.


Contact Information

Laboratory Manager

Björn Gunnarson