Oak dendrochronology

Oak (Quercus robur), togerther with beech (Fagus sylvatica), are the most common noble hardwood species in Scandinavia. Oak trees can reach the age of several hundred years and in some exeptional cases, probably up to 700-1000 years. Such lifespan and sensitivity of oak growth to summer water regime make it a good object for dendroclimatological research.

Despite large potential of oak for dendrochronological studies, most of the dendro research in Scandinavia has been concentrating on pine and spruce. Until recently, the only published research on oak dendrochronology was the works of Thomas Bartholin (Bartholin & Berglund 1975; Bartholin 1975). Since 2006 our laboratory actively works with oak within the frame of several projects.

Oak is an important tree for maintaining biological diversity. In the southern Swedish landscape, for example, large oaks provide habitat to a number of insect species associated with large-diameter living, or dead trees. Since the year 1830, when Swedish oaks lost their protection from the king, we observe a decline in the density of large oaks. Fire suppression introduced in Sweden over the course of 20th century is believed to cause a decline in the availability of sites suitable for its recruitment. Dendroecological research conducted at DELA helps understand and mimick natural disturbance regimes which would help recreate favourable conditions for oak regeneration.