Quantitative wood anatomy of Scots pine over 270 years in the foothills of the Western Sayan, Siberia

With the advancement of methods for measuring the cell anatomical structure of conifer tree rings, dendroecology now possesses a robust methodological arsenal for analyzing previously inaccessible information about environmental dynamics during wood formation (xylogenesis). Key stages in this process are represented by quantitative parameters: the number of cells in the radial row (N) indicating production, tracheidograms (intraseasonal curves) of the radial cell diameter (D) reflecting growth by expansion, and cell wall thickness (CWT) representing secondary wall deposition. These parameters serve as promising proxies, offering detailed insights into the processes of seasonal wood growth and its internal and external regulation.

In this study, we utilized long-term (approximately 270 years) cell chronologies of average and maximum D and CWT for Scots pine (Pinus sylvestris L.) in the subtaiga zone characterized by moderate moisture deficiency. We identified their nonlinear dependencies on cell production in the cambial zone, expressed by N. By indexing those parameters, we excluded these dependencies, thereby minimizing the legacy effects, including inherited external signals. Subsequently, we analyzed the influence of intra-seasonal variations in temperature and precipitation, with daily time resolution, on the anatomical structure of tree rings using the indexed cellular chronologies. Our analysis revealed intraseasonal key intervals during which these climatic factors significantly influence the radial size and cell wall thickness of pine tracheids.