The Laboratory of Dendrochronology has been active from 1992. The focus of the laboratory is on dendrochronological age determination of wood material from geological and archaeological excavations, historical constructions, art work etc. All material in the laboratory is registered and archived, and the laboratory hosts the by far most extensive and regularly updated collection of reference series for dendrochronological dating in Poland. Dating with yearly precision is commonly possible back to about 4000 year before the present (oak wood), sometimes considerably earlier than that, and in some cases it is even possible to determine during which season of the year the tree was felled. Even much older material can be dated with very high precision through combination with radiocarbon dating (weggle matching). In many cases the geographical origin of wooden artefacts can also be determined. Hence, age and provenance determination can be applied to many different types of artefacts, deposits and constructions that contain wooden materials, information of great importance within a variety of disciplines, such as geology, archaeology, history and arts. Palaeoclimate research based on tree-ring series (dendroclimatology) is also carried out at the laboratory. This type of studies can be based on living trees, historical construction timber or wood remains preserved in peat and alluvial deposits. Variations in temperature, moisture and a number of other environmental properties may be recorded as changes in ring width but also, for example, as changes in the stable carbon- and oxygen-isotope composition of wood samples.