Sapwood rings estimation for pinus sylvestris l. in Lithuania and Latvia

Pinus sylvestris L. is the predominant tree species used for wooden constructions in the Baltic area. Accordingly, the timber of Pinus is the most important object for investigation and dating carried out by dendrochronologists of the Baltic countries. However, the dating of historical Pinus is often challenging when the outer sapwood rings are missing in the wood samples. In Pinus, sapwood rings increase in number as the tree ages, and therefore calculating the approximate number of missing outer rings from a set range, a technique used for oak, is not possible. In Norway, a simple method for estimating the number of sapwood rings has been developed for some native species of conifers. The aim of this small-scale study was to assess the validity and the practical suitability of the Norwegian method for estimating the number of missing sapwood rings of mostly historical Pinus wood samples obtained in the southeastern part of the Baltic region. Our findings indicate that this method is not acceptable for estimating the number of missing sapwood rings for individual trees, but suggest that it may be applicable when dating tree-ring chronologies for a minimum of 20 trees, containing individuals up to 200 years old.