Pine and larch tracheids capture seasonal variations of climatic signal at moisture-limited sites

Abstract

Key message: Although the radial diameter and wall thickness of conifer tracheids from dry environments are 10 climatic-sensitive across the full ring area, each cell parameter has a specific zone in a ring where its climatic response 11 reaches the maximum. 12Abstract Seasonal dynamics of the timing and rate in cell production and differentiation imprint climate signals 13 into intra-ring variations of anatomical wood structure (e.g. intra-annual density fluctuations). Despite recent 14 methodological advances in quantitative wood anatomy, our understanding of xylem response to climate at the finest scale 15 of intra-ring resolution is incomplete. The goal of this study is to investigate intra-ring changes of tracheid dimensions (cell 16 radial diameter and wall thickness) controlled by moisture stress. Anatomical wood parameters of Pinus sylvestris and 17 Larix sibirica from two drought-susceptible locations in Khakassia, South Siberia, were analysed. We found that inter-18 annual variation of tracheid parameters regularly exceeds the variation between radial tracheid files. This suggests that the 19 climatic signal is recording throughout the entire ring. However, each cell parameter has a specific zone in the ring where 20 its climatic response reaches the maximum. The climatic response of the radial cell diameter has a temporal shift across the 21 ring, which is particularly apparent in pine rings. The climatic response of cell-wall thickness at the intra-ring scale has a 22 more complex pattern. Our results facilitate investigation of the climate impact on tree rings at the finest intra-ring scale by 23 quantifying the timing of climatic impact on ring structure and identifying specifically when climate impacts the formation 24 of a particular cell. 25Acknowledgements This study was supported by the Russian Foundation for Basic Research (project no. 17-04-30 00315). Collaborative activities of I. Panyushkina were sponsored by the CRDF-Global project #FSCX-18-63880-0. We would like to thank Prof. S. W. Leavitt (University of Arizona) for proofreading of the manuscript. We are grateful to 32 editor and reviewers for their helpful comments. 33Conflict of interest The authors declare that they have no conflict of interest. 34climate variations at the time of their formation, and furthermore xylem formation may be responding to climatic stress 65 with various strategies (Castagneri et al. 2017). 66The main goal of this research was to evaluate the intra-ring dynamics of climatic signals in xylem anatomical 67 parameters of conifer trees growing in a moisture-stressed environment in order to understand the climatic sensitivity of 68 xylem at very fine intra-seasonal resolution. For this, we aim to 1) develop site chronologies of xylem anatomical 69 parameters and evaluate their statistical characteristics, 2) determine the relationship between tree-ring width, cell number 70 and mean cell size, 3) compare the intra-seasonal and inter-annual variability of xylem anatomical parameters, and 71 4) identify main clima...

Water potential control of turgor‐driven tracheid enlargement in Scots pine at its xeric distribution edge

“…Whereas temperature or photoperiod are often proposed to explain wood anatomical variations under temperate and cold climates (e.g. Jenkins et al ., ; Fonti et al ., ; Björklund et al ., ), our results are consistent with studies on conifers in water‐limited environments (Castagneri et al ., , ; Belokopytova et al ., ).…”

Wood anatomical traits in black spruce reveal latent water constraints on the boreal forest

“…However, such studies mostly focused on the timings and dynamics of xylem formation, rather than anatomical traits of the resulting xylem (Buttò, Rossi, Deslauriers, & Morin, 2019). We still therefore have limited knowledge on the climate influence on xylem structure variability in the boreal biome (but see Belokopytova, Babushkina, Zhirnova, Panyushkina, & Vaganov, 2019;Rosner et al, 2016) to thoroughly assess the impact of climate change on xylem functioning and aboveground biomass carbon sequestration in the future warming conditions. Long-term environmental influence on xylem structure can be investigated through dendroanatomy, that is the retrospective and quantitative analysis of wood anatomical traits in tree-ring time series (Fonti et al, 2010).…”

New perspectives on sub-seasonal xylem anatomical responses to climatic variability

“…1). The method proposed by Belokopytova et al (2018) still allows to distinguish earlywood, latewood and transition zone properties, making it suitable for comparison with existing reconstructions.…”

“…Shifting cambial phenology has been observed in boreal and temperate environments (Rossi et al 2014), but less is known for semi-arid environments where the timing of wood formation is driven by a combination of thermal and moisture conditions (Ren et al 2018) or predominantly by water availability in hyperarid regions (Ziaco et al 2018). The intra-annual analysis of climate sensitivity performed by Belokopytova et al (2018) suggests that their single-cell normalization procedure could bypass the limitations of an equal width intra-ring sectioning, making it possible to extend retrospective inferences on cambial phenology in species characterized by higher phenological plasticity and frequent Intra Annual Density Fluctuations (IADFs). Fig.…”

“…cell diameter (red line) are developed for each position and then correlated with moving averages of daily climatic data of a given climatic parameter, i.e. temperature (see Belokopytova et al 2018). Correlation for each section is generally shifted temporally depending on the timing of formation of each section…”