Climatic reactions in the radial growth of Pinus sibirica Du Tour from the lower to the upper limit along the Western Sayan Mountains, Siberia

In mountains, the reactions of trees to climatic fluctuations and changes depend on various factors, including ecological gradients and species. This study investigates the radial growth of Siberian stone pine ( Pinus sibirica Du Tour), a widespread key conifer in the Siberian taiga, across its elevational range in the Western Sayan Mountains of Southern Siberia. Wood samples were gathered along three latitudinal-elevational transects spaced ca. 80-100 km apart from each other, spanning from west to east across the Western Sayan region. The midpoint of these transects coincided with a large reservoir on the Yenisei River. Each transect encompassed three distinct sites: the lower limit of species growth at 400-500 m a.s.l., a site located at 1700-2050 m a.s.l. near the upper forest line, and an intermediary site falling between these boundaries. A spectacular synchronicity was observed in TRW residual chronologies ( R =0.56-0.78 over 1936-2010) and their climatic responses across all sites near the upper forest line and 200-300 m below it. In these areas, temperatures showed a predominantly positive impact from the previous July-August to the current August, except for the end of March-April. The negative influence of excess precipitation during these seasons decreased from west to east, whereas early spring precipitation exhibited a positive correlation with TRW. At the lower limit of growth, the TRW chronologies of species showed lower correlation values between each other ( R =0.26-0.36). Here, the species exhibited a positive impact of annual precipitation and a negative influence of temperature, particularly in the previous August and current May-June, albeit of varying intensities. At the mid-montane site, located at 300-500 m above the lower limit of species growth, a mixed climatic influence was observed with a positive response to annual temperatures and June precipitation. Further, the pointer years of the maximum or minimum indexed TRW also occurred much more synchronously in highland forests. The observed shifts in climatic responses indicated that climate warming has advanced the onset of vegetation and delayed the dormancy in these regions. The majority of the Siberian stone pine stands under consideration showed a positive response to warming. Interestingly, an absence of steady growth decline, even in the foothills, indicated a non-climatic range border. The study approach allowed us to recognize with daily resolution annual and seasonal climatic variables impacting stone pine growth that can be probably reconstructed on a local (precipitation) or regional (temperature) scale. This study enhanced the understanding of climate-growth relationships in P. sibirica , offering insights into the species' resilience and vulnerability across ecological gradients in response to changing climatic conditions.