1. Temperature and photoperiod interactions influence the cessation of wood growth in three temperate and boreal conifersJianhong Lin, Cyrille Rathgeber, Patrick Fonti, Sergio Rossi, Henri E. Cuny, Edurne Martinez Del Castillo, Katarina Čufar, Jesús J. Camarero, Alessio Giovannelli, Harri Mäkinen, Peter Prislan, Walter Oberhuber, Hanuš Vavrčík, Jianguo Huang, Andreas Gruber, Vladimir Gryc, Václav Treml, Martin De Luis, Jožica Gričar, Nicolas Delpierre, 2026, original scientific article Abstract: Cambium phenology is a crucial process in wood production and carbon sequestration of forest ecosystems. Although cambium phenology has been widely studied, research specifically focusing on the cessation of wood formation remains limited. To better understand the influence of environmental and intrinsic factors on the cessation of wood formation, we built and compared three ecophysiological models (temperature sum model, photoperiod-influenced temperature sum model and soil moisture- and photoperiod-influenced temperature sum model) in their ability to predict the date of cessation of xylem cell enlargement (cE) in three major Northern Hemisphere conifer species (Black spruce, Norway spruce and Scots pine). We developed these models based on xylogenesis data collected for 130 site‐years across Europe and Canada. Our results demonstrate that the photoperiod-influenced temperature sum model is well-supported by data across all conifer species, with a RMSE of 9.2 days, suggesting that both temperature and photoperiod are critical drivers of wood growth cessation. However, incorporating soil moisture effects does not improve model performance. Our model effectively captures the inter-site variability in cE across a wide environmental gradient, with a fair model efficiency (ME = 0.51 ± 0.22), but performed less well for annual anomalies (ME = 0.10 ± 0.09). Additionally, we found that the total ring cell number also affected prediction accuracy. Using this model, we reconstructed historical trends in cE over the past six decades and found a trend to delayed cessation dates. This delay varied geographically, with slower shifts at higher latitudes and elevations, likely due to constrained cambial responses and conservative growth strategies in colder regions. Our model framework offers a simple yet accurate approach for predicting wood growth cessation at large spatial scales, providing a basis for integrating cambium phenology into land surface models and forest productivity assessments.
Keywords: cambium phenology, ecophysiological models, xylem formation, climate change, global warming, northern hemisphere forests
Published in DiRROS: 12.02.2026; Views: 379; Downloads: 100
 Full text (1,76 MB)
This document has many files! More... |
2. Age-dependent moisture response of conifers near their cold range limitJan Tumajer, Grudd Håkan, Jernej Jevšenak, Andreas J. Kirchhefer, Francesco Marotta, Jiří Mašek, Kiara Maria Nowatzki, Nikolaus Obojes, Markus Stoffel, Václav Treml, Jelena Lange, 2025, original scientific article Abstract: Growth dynamics of cold subarctic and subalpine forests are primarily sensitive to temperature, but growth responses may vary across regions or shift over tree ontogeny. Systematic assessments of spatial, interspecific, and demographic variation in temperature and moisture limitation of tree growth at cold distribution margins are essential for enhancing our understanding of how these ecosystems will evolve under climate regimes. To address this gap, we built a network of 22 tree-ring width chronologies from cold forests covering two regions (Fennoscandia, European Alps), three species (Pinus sylvestris, Pinus cembra, Larix decidua), and two age cohorts (45–100 and >150 years). We combined daily climate-growth correlations with the process-based Vaganov-Shashkin growth model to identify differences in critical growth factors between species and age cohorts. In addition, we assessed the coincidence of unusually wide and narrow tree rings with years of specific climatic anomalies. Although growing season temperature was the dominant growth-limiting factor, seasonal effects of water balance on tree growth were considerably large and varied systematically between regions, species, and particularly age cohorts. The growth of young P. sylvestris in Fennoscandia responded negatively to water balance and narrow rings coincided with wet years. In contrast, the growth of young P. cembra in the Alps was drought-limited. Old trees of all species and both age cohorts of L. decidua in the Alps showed limited sensitivity to water balance. The patterns of climate-growth responses in cohort chronologies based on tree age at the year of coring were similar to ontogenetic shifts of climate-growth responses if chronologies were based on the cambial age of individual rings. Our results stress the need to account for interspecific and demographic differences in sensitivity to climate in large-scale studies of cold forest ecosystems.
Keywords: boreal forest, Larix, subalpine forest, pinus, tree ring, Vaganov-Shashkin model
Published in DiRROS: 04.06.2025; Views: 684; Downloads: 349
Full text (10,22 MB)
This document has many files! More... |
