Contrasting stem NSC dynamics in evergreen and deciduous conifers of a Siberian mixed forest

Abstract Key message Siberian evergreen conifers maintain stable starch reserves, while deciduous larch adopts a dynamic carbon strategy with autumn NSC accumulation to fuel spring growth, enhancing boreal forest resilience. Abstract Non-structural carbohydrates (NSC) play a fundamental role in tree growth, metabolism, and resilience by buffering temporal imbalances between carbon supply and demand. However, comparative studies integrating long-term growth records with stem NSC dynamics remain scarce in Siberian boreal forests. Here, we combine six decades of tree-ring width (TRW; 1960–2022) analyses with radial stem NSC profiling (1993–2022) and seasonal NSC measurements during the 2022 growing season to investigate growth responses and stem carbohydrate storage dynamics in three co-existing Siberian conifers ( Pinus sylvestris L., Abies sibirica Ledeb., and Larix sibirica Ledeb.). Tree-ring chronologies reveal species-specific climate-growth relationships despite the common environment. P. sylvestris responds positively to warm autumn and late winter temperatures, A. sibirica to previous autumn and current summer precipitation, whereas L. sibirica shows greater sensitivity to current-year temperature. Stem NSC dynamics also differ markedly among species. The evergreen P. sylvestris and A. sibirica maintain relatively stable, starch-dominated NSC pools, whereas the deciduous L. sibirica exhibits pronounced seasonal fluctuations and substantially greater autumn reserve accumulation. Across all species, NSC concentrations increased towards the outermost sapwood. These findings demonstrate that co-existing boreal conifers differ in both climate-growth relationships and stem NSC storage dynamics. Contrasting stem storage patterns provide a physiological framework for interpreting species-specific growth responses and may contribute to understanding the resilience of mixed boreal forests under future climate change.