[A-CG31] Climate Variability and Predictability on Subseasonal to Centennial Timescales

[ACG31-P10] Modeling the kinetics of cell enlargement of larch trees growing in the permafrost zone of Siberia

*Margarita Popkova¹, Vladimir Shishov¹ (1.Siberian Federal University)

Keywords:Process-based Vaganov-Shashkin model, Wood anatomy, Cell production

Wood formation allows trees to continuously adjust their structure to survive under changing environmental conditions. Understanding what determine its adjustment is crucial to evaluate impacts of climatic changes on trees and forests growth. Despite efforts to characterize wood formation, little is known on its impact on the xylem cell structure. The process-based models of tree-ring growth contribute to better understanding of the link between environment, wood formation and structure and allow projecting further growth. In this study we apply the VS-model to model and analyse the intra-annual cell anatomy of Larix gmelinii Rupr (Rupr) growing in continuous permafrost zone of Central Siberia. Anatomical measurements obtained between 1950 and 2011 have demonstrated the low number of cells determining low tree-ring growth is due to the challenging climatic conditions of the permafrost zone. The parameterization of the VS-model provided highly significant positive correlations between simulated growth curves and initial tree-ring chronology (R = 0.65). The results of timing procedure show that VS-model makes it possible to link climate and the tree-ring structure. The procedure revealed strong relationships between modelled growth rates and measured tracheid radial sizes for the full period 1950 - 2011. The results of timing procedure the growth rates modeled for the 2011 growing season fit well the timing (R = 0.91) and the observed number of cambial and enlarging cells (R = 0.78 and 0.87, respectively). The comparison the number of days from the start of the growth season to when the first cell moved into the enlargement zone with the average growth rates during this period showed that years with low growth rates at the beginning of the growing season correspond to continuous lags in the cells escape from the cambial zone. Using a new approach to determine the timing of cell enlargement the number of enlarging cells modeled for the 2011 growing season matched well with the number of enlarging cells observed on micro-cores collected in the field. This study has demonstrated that the VS model successfully simulates xylogenesis for larch growing in the permafrost zone, both in case of “average tree” and for individual plants. This approach to modelling intra-annual dynamics has considerable potential for studying the influence of climate on tree ring growth and formation.
This work was supported by Russian Science Foundation (Grant 22–14–00048, methodology development, design of the model algorithm, testing the algorithm, software development). Margarita I. Popkova was supported by the Russian Ministry of Science and Higher Education (Project # FSRZ-2023–0007, measurements and initial data processing).