Wood formation allows trees to adjust in a changing climate. 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 cellular structure. In this study we apply the Vaganov-Shashkin model to generate synthetic tracheidograms and verify its use to investigate the formation of intra-annual density fluctuations (IADF), one of the most frequent climate tree-ring markers in drought-exposed sites. Results indicate that the model can produce realistic tracheidograms, except for narrow rings (<1 mm), when cambial activity stops due to an excess of drought or a lack of growth vigor. These observations suggest that IADFs are caused by a release of drought limitation to cells formation in the first half of the growing season, but that narrow rings are indicators of an even more extreme and persistent water stress. Taking the example of IADFs formation, this study demonstrated that the Vaganov-Shashkin model is a useful tool to study the climatic impact on tree-ring structures. The ability to produce synthetic tracheidogram represents an unavoidable step to link climate to tree growth and xylem functioning under future scenarios.
There is limited information on intra-annual plasticity of secondary tissues of tree species growing under different environmental conditions. To increase the knowledge about the plasticity of ...secondary growth, which allows trees to adapt to specific local climatic regimes, we examined climate-radial growth relationships of Norway spruce Picea abies (L.) H. Karst. from three contrasting locations in the temperate climatic zone by analyzing tree-ring widths for the period 1932-2010, and cell characteristics in xylem and phloem increments formed in the years 2009-2011. Variation in the structure of xylem and phloem increments clearly shows that plasticity in seasonal dynamics of cambial cell production and cell differentiation exists on xylem and phloem sides. Anatomical characteristics of xylem and phloem cells are predominantly site-specific characteristics, because they varied among sites but were fairly uniform among years in trees from the same site. Xylem and phloem tissues formed in the first part of the growing season seemed to be more stable in structure, indicating their priority over latewood and late phloem for tree performance. Long-term climate and radial growth analyses revealed that growth was in general less dependent on precipitation than on temperature; however, growth sensitivity to local conditions differed among the sites. Only partial dependence of radial growth of spruce on climatic factors on the selected sites confirms its strategy to adapt the structure of wood and phloem increments to function optimally in local conditions.
Russia, the country with the most forested area, significantly influences global climate, carbon, and water dynamics. In addition, a considerable part of the Russian forests is in remote regions with ...a low direct anthropogenic disturbance, but at the same time, recently experiencing unprecedented warming. This combination of factors makes Russia a hotspot for dendrochronological and dendroanatomical studies, providing a valuable perspective on the consequences of climate change in a global context. Dendroanatomy is a powerful dendrochronological tool that provides a robust insight into xylem traits, their relation to climate conditions during tree-rings formation, and the cell structure-function relationship over time (tree life span). Although dendroanatomy in Russia has been gaining momentum lately, there is a long tradition of characterizing and modeling wood anatomical traits, including the development of novel methodologies, hardware and software since the mid-20th century. Unfortunately, in many cases, these advances have been hidden from the international readership because most of them were published in Russian. This descriptive inventory presents an overview of dendroanatomical studies carried out in Russia since the mid-20th century. It focuses on different periods and topics to facilitate its accessibility and highlight its contribution to the global dendrochronological community.
•Soil moisture at our site is the factor most limiting growth and tracheid size.•Climatic response of tracheid size of EW, TW and LW is shifted by one month.•Summer drought mainly impact the width of ...the second part of the ring.•Modeled and observations indicate a higher carbon fixation in wetter summers.
Climate affects wood formation with consequences for the functioning and survival of trees. Since tree-rings tissues (i.e., earlywood and latewood) are formed at different time in the season, the impact of climate change might differently affect their functions.
In this study, we combine quantitative tracheid anatomy with the Vaganov-Shashkin growth model (VS-model) to investigate how summer drought affected the annual ring structure of Pinus sylvestris L. from a forest-steppe zone in Southern Siberia. In particular, we used climate-growth relationships over a 50-year period to identify the timing of climatic signal of early-, transition-, and late-wood tracheid’s diameters (DEW, DTW and DLW). Corresponding daily growth rates (Gr) obtained by the VS-model were applied to calculate the changes in the width of the relative tree-ring sectors considering different levels of aridity.
Results indicate that tracheid size is sensitive to drought with temporal shifts among the climatic signal of DEW (in May), DTW (June) and DLW (July). A comparison of modeled daily-growth rate cumulated over the climatic window of each ring sector and grouped by years with different level of aridity, indicated that a release of summer drought mostly affected the widths of the transition (+28.1%) and (+48.6%) latewood sectors, thus matching observations performed on the same cores.
These results suggest that current changes in climate seasonality, as occurring in the selected area, are positively impacting both the hydraulic efficiency (by increasing the diameter of the earlywood cells) and the latewood width of the wood produced in the area.
RAPTOR: Row and position tracheid organizer in R Peters, Richard L.; Balanzategui, Daniel; Hurley, Alexander G. ...
Dendrochronologia (Verona),
February 2018, 2018-02-00, Volume:
47
Journal Article
Peer reviewed
Mechanistic understanding of tree-ring formation and its modelling requires a cellular-based and spatially organized characterization of a tree ring, moving from whole rings, to intra-annual growth ...zones and individual cells. A tracheidogram is a radial profile of conifer anatomical features, such as lumen area and cell wall thickness, of sequentially- and positionally-ranked tracheids. However, its construction is tedious and time-consuming since image-analysis-based measurements do not recognize the position of cells within a radial file, and present-day tracheidograms must be constructed manually.
Here we present the R-package RAPTOR that complements tracheid anatomical data obtained from quantitative wood anatomy software (e.g., ROXAS, WinCELL, ImageJ), with the specific positional information necessary for the automated construction of tracheidograms. The package includes functions to read and visualize tracheid anatomical data, and uses local search algorithms to ascribe a ranked position to each tracheid in identified radial files. The package also provides functions to ensure that tracheids are adequately aligned for identifying the first tracheid in each radial file, and obtaining the correct ranking of tracheids along each radial file. Additional functions allow automating the analyses for multiple samples and rings (batch mode) and exporting data and plots for quality control.
RAPTOR allows tracheidogram users to take advantage of the latest generation of cell anatomical measuring systems. With this R-package we aim to facilitate the construction of more robust and versatile tracheidograms for the benefit of the research community.
A detailed understanding of how the climate models the hydraulic system of trees is still lacking, in spite of the need to understand tree response to the ongoing process of climatic change. A ...systematic correlation of tracheid anatomical features with climate has not been implemented in Mediterranean ecosystems, where climatic change is expected to be particularly intense. We measured ring width and cell number—in addition to intraring position, lumen size, and wall thickness of tracheids—in 10Juniperus thuriferaindividuals from north-central Spain. We used this information to perform an exploratory analysis of how these parameters correlated with climatic variables in 1965–2004. Cell number and ring width shared a relatively similar climatic signal, whereas the anatomical variables provided differentiated and diverse signals about climatic conditions during their formation. Earlywood and latewood tracheids differed in controlling factors, with earlywood tracheid size and wall thickness being positively related to rainfall during early summer and latewood tracheid size being positively related to August temperature. Tracheid anatomical variables improved our understanding of climate effects on tree growth and wood formation under harsh environmental conditions, as those experienced in continental Mediterranean climates, where limiting factors show multiple shifts across the year.
Quantitative wood anatomy (QWA) is a growing field of dendrochronology that allows obtaining a large number of parameters as the number, size and spatial arrangement of cellular elements, elements ...that highlight the adjustments of trees to their environment. In this work, we presented the free/libre open-source software AutoCellRow (ACR), a ready-to-use tool for automatic QWA in conifers. The ACR analyzes radial files of cells on cross-sections views of tree rings and provides automatic measurements of different cell parameters (e.g., lumen radial diameter, double cell wall thickness and cell radial diameter) for each cell along the selected radial file. The ACR measurements are based on high performed image analysis of xylem cells. The accuracy of the software measurements was tested in cross-sections of five conifer species from a semi-arid area of southern Siberia, and compared with measurements obtained by a semiautomatic tool. Our results suggested high accuracy in the ACR cell traits measurements, facilitating and speeding the analysis of quantitative wood anatomy in conifers over radial files of cells.
Knowledge about past climates, especially at a seasonal time scale, is important as it allows informed decisions to be made to mitigate future climate change. However, globally, and especially in ...semi-arid Tropics, instrumental climatic data are scarce. A dendroclimatic approach may fill this gap, but tropical dendrochronological data are rare and do not yet provide fine resolution intra-annual information about past climates. Unlike in the Tropics, in the Mediterranean, temperate, alpine, and arctic regions, dendroanatomy and quantitative wood anatomy (QWA) are progressing fast attaining an intra-annual resolution, which allows a better understanding of seasonal climate dynamics and climate-growth relationships. The existing dendroanatomical and QWA methods aren't suitable for tropical trees because they do not consider the high variation in tree ring width and the frequent occurrence of micro-rings containing only a few tracheids per radial file. The available tracheid analysis programs generally fail to provide multiple sectors for micro-rings and they are unable to compute most of the useful dendroanatomical parameters at fine temporal resolutions. Here, we present a program (SabaTracheid) that addresses the three main standard tasks that are necessary for QWA and dendroanatomy before running a climate analysis: (1) tracheidogram standardization, (2) sectoring, and (3) computing QWA and dendroanatomical variables. SabaTracheid is demonstrated on African Juniper (
Hochst. ex Endl), but it is potentially able to provide fine-resolution QWA and dendroanatomic data that could be used for dendroanatomical studies in all regions of the world.
is a freeware that quickly and accurately standardizes tracheidograms, divides tree rings into multiple regular sectors, computes useful dendroanatomic and QWA variables for the whole tree rings, early- and latewood portions, and each sector separately. This program is particularly adapted to deal with high inter-annual growth variations observed in tropical trees so that it assures the provision of complete sectoral QWA and dendroanatomical data for micro-rings as well. We demonstrate
using a dataset of 30
tree rings from the Blue Nile basin, in Ethiopia.
's ability to provide fine resolution QWA and dendroanatomic data will help the discipline develop in tropical as well as in the Mediterranean and temperate regions.
Wood anatomy was offered as spatiotemporal proxy record for tracheid differentiation kinetics due to its advantages in terms of much longer cover period and less demanding measurements. In this ...study, external and internal regulation of earlywood-to-latewood transition and properties of latewood of Picea obovata Ledeb were considered. The values and interrelations between cell number, tree ring width, maximal and mean radial cell diameter, maximal cell wall thickness and position of the transition to thick-walled tracheids were investigated within site and along the altitudinal gradient. Correlations with moving 21-day climatic series were used to estimate high-resolutional external influences. Relationships between tree ring traits are spatially stable and close within one stage of differentiation and between cells production and expansion. Relationships between sites differ in upper and lower parts of the gradient. Most of traits respond to the primary limiting factors near summer solstice; however, maximal cell wall thickness responds positively to the temperatures at the + 10 °C threshold. Altitudinal anatomical patterns revealed interaction of intrinsic and external factors in the regulation of tracheid differentiation. Timing of climatic response highlighted role of photoperiod as a trigger in the earlywood-to-latewood transition, and crucial role of the growth season ending for latewood development.
Quantitative wood anatomy (QWA) is widely used to resolve a fundamental problem of tree responses to past, ongoing and forecasted climate changes. Potentially, QWA data can be considered as a new ...proxy source for long-term climate reconstruction with higher temporal resolution than traditional dendroclimatic data. In this paper, we considered a tracheidogram as a set of two interconnected variables describing the dynamics of seasonal variability in the radial cell size and cell wall thickness in conifer trees. We used 1386 cell profiles (tracheidograms) obtained for seven Scots pine (Pinus sylvestris) trees growing in the cold semiarid conditions of Southern Siberia over the years 1813–2018. We developed a “deviation tracheidogram” approach for adequately describing the traits of tree-ring formation in different climate conditions over a long-term time span. Based on the NbClust approach and K-means method, the deviation tracheidograms were reliably split into four clusters (classes) with clear bio-ecological interpretations (from the most favorable growth conditions to worse ones) over the years 1813–2018. It has been shown that the obtained classes of tracheidograms can be directly associated with different levels of water deficit, for both the current and previous growing seasons. The tracheidogram cluster reconstruction shows that the entire 19th century was characterized by considerable water deficit, which has not been revealed by the climate-sensitive tree-ring chronology of the study site. Therefore, the proposed research offers new perspectives for better understanding how tree radial growth responds to changing seasonal climate and a new independent proxy for developing long-term detailed climatic reconstructions through the detailed analysis of long-term archives of QWA data for different conifer species and various forest ecosystems in future research.
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