The Problem of Cross-Dating Siberian Pine and Siberian Larch on the Upper Forest Boundary in the Altai-Sayan Ecoregion

In dendroclimatic studies, there is a need for high-quality data series reflecting the state of the environment in the past. The construction of long-term tree ring width (TRW) chronologies (in terms of the combined qualities of being one of the best sources of paleoclimatic information) is associated with the problem of finding a source of paleowood, which will allow it to extend further into the past. This paper considers the prospect of extending the existing 2367-year TRW chronology (on Siberian larch) due to the attraction of the wood of Siberian pine, which is widely presented in collections collected on the premises of the Altai glaciers. The results of a consideration of various parameters of annual rings clearly and convincingly demonstrated that, at the upper edge of the forest, the use of a parameter such as the delta of optical density of the annual ring will allow one to reliably cross-date samples of different tree species and extend this TRW chronology to the past.