Growth Rings Research Articles

Age of heartwood initiation in trunks of young Pinus sylvestris L. trees in the taiga zone

Summary This work is part of a project investigating the heartwood formation process in Scots pine. Despite the economic and ecological importance of pine heartwood (HW), the process of its formation in many respects remains poorly understood. Scientists believe that HW formation in Scots pine begins at 9–20 years, however, systematic studies of HW initiation age in this species have not previously been conducted. Samples were collected from 105 P. sylvestris trees aged 10 to 25 years, growing in the middle and northern taiga subzones, as well as on the border of the northern taiga subzone with the tundra. Samples were taken at the trunk base according to a single technique and processed using two biochemical (peroxidase activity, pinosylvin presence) and two anatomical markers (presence of extractives on the tracheid pit membranes, nuclei disappearance) characterizing different events during HW formation. Biochemical markers showed an overestimation in the number of HW annual rings compared with HW determination based on anatomical criteria by 1–3 years, on average. Attempts to detect peroxidase activity showed a negative result in the inner sapwood annual ring, while detectable pinosylvin accumulation occurred in the transition zone (TZ). We have detected for the first time true HW (without living cells) in Scots pine samples with a cambial age (CA) of 15–17 years. The number of growth rings in TZ and HW in young trees depended on growth conditions. These results are important for understanding the mechanisms of HW formation and developing realistic models of this process, including changing climate conditions.

Late Holocene seasonal human predation of otariids in Santa Cruz River mouth, Southern Patagonia, Argentina

According to archaeological data, Otaria flavescens and Arctocephalus australis were exploited at the mouth of the Santa Cruz River by hunter-gatherers in the late Holocene. These studies suggest the past existence of reproductive colonies from where individuals of different ages were taken, highlighting the offspring available in the austral summer. This paper presents new information on sex, age, and season of death based on the study of teeth growth layers and rings recorded on canines of both species recovered in three archaeological sites located in Punta Entrada, on the southern bank of Santa Cruz River. The results confirm that otariids were captured in the austral summer and show that winter and spring were also important seasons. Prey included females, pups, and adult males captured according to the abundance of each age group at different seasons of the year. These data are in agreement with those obtained from other lines of evidence, such as osteometry and sclerochronology, which indicate this sector of the Patagonian coast was occupied recurrently to hunt otariids as one of the main resources taken by hunter-gatherers when visiting Punta Entrada at different times of the year.

A quantitative analysis of leaf life span reveals the Mesozoic significant gymnosperm Xenoxylon as evergreen: First evidence from the Early Cretaceous Jehol Biota in northeastern China

The Early Cretaceous Jehol Biota in western Liaoning Province of China and adjacent regions, is one of the most spectacular Mesozoic terrestrial lagerstätten in East Asia. Diversified fossil wood has been reported for the last two decades for the Jehol Biota. However, little is known about the fossil wood from the Lower Cretaceous Jiufotang Formation in the Kazuo area of western Liaoning. Here, we report new fossil wood material from the Lower Cretaceous Jiufotang Formation in Kazuo County of western Liaoning Province, northeastern China with well-preserved xenoxylean radial tracheid pitting and window-like cross-field pitting. Due to a novel combination of radial tracheid pitting, cross-field pitting and ray height, a new species, Xenoxylon kazuoense Xie, Wang, Tian et D.Uhl sp. nov., is recognized here belonging to the gymnosperm. Based on the well-preserved tree growth rings, we first perform a quantitative analysis of leaf life span for the Mesozoic common gymnosperm Xenoxylon. The result shows the tree X. kazuoense sp. nov. was evergreen with a leaf retention time (LRT) of 3–15 years. The discovery of this new species leads to a further understanding of the biodiversity of fossil wood in the Early Cretaceous Jehol Biota and the leaf phenology of trees growing in this area during the Early Cretaceous.

Plant morpho evo-devo.

Evo-devo is often thought of as being the study of which genes underlie which phenotypes. However, evo-devo is much more than this, especially in plant science. In leaf scars along stems, cell changes across wood growth rings, or flowers along inflorescences, plants trace a record of their own development. Plant morpho evo-devo provides data that genes could never furnish on themes such as heterochrony, the evolution of temporal phenotypes, modularity, and phenotype-first evolution. As plant science surges into increasingly -omic realms, it is essential to keep plant morpho evo-devo in full view as an honored member of the evo-devo canon, ensuring that plant scientists can, wherever they are, generate fundamental insights at the appropriate level of biological organization.

A unique Late Cretaceous fossil wood assemblage from Chilean Patagonia provides clues to a high‐latitude continental environment

AbstractFossil plants, including large trunks, stems, some branches, and twigs, were collected from the Maastrichtian (68.9 Ma), upper Dorotea Formation in the Magallanes–Austral Basin, 16 km north of the Cerro Guido–Las Chinas complex in the southern Chilean Magallanes region. These fossil trunks range from 0.2 to 2.2 m in length. Petrographic slides were made in three sections (transverse, radial and tangential) and analysed under a light microscope to study the permineralized fossils. The woods and stems belong to Austroginkgoxylon gen. et sp. nov., Agathoxylon antarcticum, Podocarpoxylon paradoxi sp. nov., Podocarpoxylon mazzonii, Palmoxylon subantarcticae and Notomalvaceoxylon magallanense gen. et sp. nov. The growth rings of gymnosperms and anatomical characters of angiosperms were analysed to obtain palaeoecological data. Interactions between gymnosperm roots growing into the secondary xylem of an angiosperm (nurse logs) are recorded. The data obtained from the fossil woods suggest warm and humid conditions in this southern South American locality during the Late Cretaceous, providing a unique opportunity to study continental environments at high southern latitudes, which are poorly represented on a global scale.

Automated tree ring detection of common Indiana hardwood species through deep learning: Introducing a new dataset of annotated images

Tree-ring dating enables gathering necessary knowledge about trees, and it is essential in many areas, including forest management and the timber industry. Tree-ring dating can be conducted on either wood’s clean cross-sections or tree trunks’ rough end cross-sections. However, the measurement process is still time-consuming and frequently requires experts who use special devices, such as stereoscopes. Modern approaches based on image processing using deep learning have been successfully applied in many areas, and they can succeed in recognizing tree rings. While supervised deep learning-based methods often produce excellent results, they also depend on extensive datasets of tediously annotated data. To our knowledge, there are only a few publicly available ring image datasets with annotations. We introduce a new carefully captured dataset of images of hardwood species automatically annotated for tree ring detection. We capture each wood cookie twice, once in the rough form, similar to industrial settings, and then after careful cleaning, that reveals all growth rings. We carefully overlap the images and use them for an automatic ring annotation in the rough data. We then use the Feature Pyramid Network with Resnet encoder that obtains an overall pixel-level area under the curve score of 85.72% and ring level F1 score of 0.7348. The data and code are available at https://github.com/wufanyou/growth-ring-detection.

Dating the penultimate great earthquake in south-central Alaska using tree-ring crossdating and radiocarbon wiggle-matching

A forest bed of tree stumps currently in the intertidal zone at Girdwood, south-central Alaska, records coseismic submergence during the penultimate great earthquake. Tree-ring samples from ten spruce stumps were crossdated to develop a 149-year-long ring-width chronology. Radiocarbon wiggle-matching found that single-ring ages from the chronology were offset 28 ± 7 years older than the IntCal20 calibration curve and that the last ring of the chronology dated as 1169 to 1189 CE (781–761 cal. yr. BP) at the 95% confidence level. Bark was observed on some stumps, six samples had the same year for the last growth ring, and so this wiggle-match date is also the best estimate of the date of the penultimate great earthquake. This date is in good agreement with a date for this event in a seismo-turbidite record from Skilak Lake but not with previous dates from Bayesian models of maximum- and minimum-limiting ages from coastal salt marshes. Reanalysis of the coastal salt marsh ages with the data grouped by area, context and material found that outer wood samples from stumps at coseismic submergence sites and a Bayesian limiting age model based on just herbaceous plant ages from Turnagain Arm and the Copper River area are both consistent with our wiggle-match date. Furthermore, coseismic emergence ages from Cape Suckling and Yakataga are older than the penultimate earthquake and so likely relate to an earlier uplift event in this eastern area. The rupture extent during the penultimate great earthquake appears to have been less than in the 1964 great earthquake and the interseismic interval between these two events was 785 ± 10 years.

Prognostic role of the log odds of positive lymph nodes in Western patients with resected gastric cancer: A comparison with the 8th edition of the TNM staging system.

Several alternative lymph node staging systems have recently been described for gastric cancer. The log odds of positive lymph nodes (LODDS) system may be superior to the pN stage (American Joint Committee on Cancer) and lymph node ratio systems in predicting outcomes for patients with gastric cancers, as indicated by some researchers. Most studies, however, have been conducted in Asian countries, and conflicting results have been reported by other investigators. We conducted a retrospective study of all 377 cases of gastric cancer resected at a tertiary hospital in Spain between 2000 and 2019. Clinicopathologic features were collected, LODDS were calculated and categorized into 5 groups (S1-S5), and statistical analysis was performed. The cases included (n = 315) were classified as S1 (25.6%), S2 (18.4%), S3 (21.3%), S4 (20.3%), and S5 (14.4%). The LODDS classification was significantly associated with tumor size, Laurén subtype, presence of signet ring cells, tumor grade, perineural infiltration, lymphovascular invasion, growth pattern, pT, tumor recurrence, and death. Kaplan-Meier analysis based on the LODDS classification demonstrated improved patient stratification compared with the pN stage for both overall survival (OS) and disease-free survival (DFS). Area under the curve values for recurrence and death were superior for the LODDS classification, and this classification was independently related to OS and DFS. In addition, the LODDS classification successfully divided patients without lymph node metastases (pN0) into subgroups with distinct prognoses. For our cohort, the LODDS system showed better prognostic performance than pN stage; it was an independent predictor of OS and DFS, and it provided valuable prognostic information in cases without lymph node metastases. Its prognostic accuracy, however, decreased in cases with fewer than 16 lymph nodes resected.

Ontogeny of multiple variants in the stems of Phaseolus lunatus L. (Fabaceae)

Development of the cambial variant is characteristic to most of the climbing members of the Fabaceae and is considered as an alternative path to increase their stem diameter for efficient supply of minerals and photosynthate within limited stem diameter. These alternative forms of secondary growths are ascribed as an adaptive character to increase stem flexibility and most often they are found to be taxon-specific. In the present study, histological investigation on the main stems of Phaseolus lunatus L. (Fabaceae) showed multiple combinations of variant secondary growth like the formation of vascular cylinders external to the secondary phloem and proliferation of parenchyma (axial and ray) followed by the development of interxylary phloem, interxylary cambia (functionally regular and inverse) and ray cambia. The secondary xylem produced by regular cambium was diffuse-porous with indistinct growth rings and composed of an abundance of thin-walled unlignified parenchyma. With the increase in age, phloem rays underwent dilatation, subsequently became meristematic and formed oval to circular vascular cylinders/units with irregular orientation. Concomitantly, dedifferentiation xylem parenchyma not only formed small islands of interxylary phloem but also led to the origin of interxylary cambial segments that differentiated bidirectionally and deposited xylem and phloem having inverse, diagonal, tangential or radial orientations. Similar cell division activity was also observed in marginal xylem ray cells (ray cambium) that produced both the xylem and phloem on either side. All these cambial variants are described in detail and their possible significance in the climbing habit is discussed.

Drought reconstruction since 1796 CE based on tree-ring widths in the upper Heilongjiang (Amur) River basin in Northeast Asia and its linkage to Pacific Ocean climate variability

Abstract. The economic and environmental impacts of persistent droughts in East Asia are of growing concern, and therefore it is important to study the cyclicity and causes of these regional droughts. The self-calibrating Palmer drought severity index (scPDSI) has been extensively employed to describe the severity of regional drought, and several scPDSI reconstructions based on tree rings have been produced. We compiled a tree-ring chronology for Hailar pine (Pinus sylvestris var. mongolica) from two sites in the Hailar region in the upper Heilongjiang (Amur) River basin. Analysis of the climate response revealed that scPDSI was the primary factor limiting tree ring growth from May to July. The mean May to July scPDSI in the Hailar region since 1796 was reconstructed from the tree-ring width chronology. The results of spatial correlation analysis revealed that the reconstructed scPDSI in this region responded significantly to climate change. Analysis of the synoptic climatology indicated that the drought in the upper Heilongjiang (Amur) River basin is closely related to El Niño–Southern Oscillation (ENSO) and the Silk Road teleconnection. The results of atmospheric water cycle analysis show that water vapor transport processes are the dominant factor in the development of drought in this region.

Influence of growth ring number and width on elastic constants of poplar

The objective of this work was to evaluate the effect of growth ring number (specimens including 2, 4, and 6 rings from the bark) and growth ring width on elastic constants in the radial direction of Populus x canadensis, which has not been revealed before. The longitudinal (2.25 MHz) and transverse (1 MHz) ultrasonic waves were propagated to calculate the longitudinal (VRR) and shear (VRL, VLR, VTR, and VRT) wave velocities and used to determine the elasticity modulus (ER), and shear moduli (GRL and GRT). The average growth ring widths of specimens including 2, 4, and 6 rings were 17.0 mm, 17.8 mm, and 18.2 mm, respectively. According to the results, only VRL steadily increased with increased ring number, while other velocities fluctuated. The same fluctuations were observed for moduli except for GLR, which constantly increased with ring number. The influence of ring number on velocity was statistically significant only for VRL and VRT. However, all moduli were significantly affected by ring number. Linear regression statistics revealed that there were significant relations between the ring width and density, VRL, VLR, VRT, GRL, and GRT.

Tumor Profiles of Late Presentation Uveal Ring Melanoma With Novel Characteristics - A Case Series.

The purpose of this study was to investigate the clinical features, tumor characteristics, including histopathology and cytogenetic analysis, and management of patients with uveal ring melanoma in New Zealand. A retrospective review was conducted on all uveal melanoma cases treated in a single national oncology center in New Zealand. The study period was from January 1, 2013 to December 31, 2022 (10 years). Written consent was obtained from all patients included in this case series. Uveal ring melanoma of ciliary body origin (n = 4) comprised 0.7% of all uveal melanomas (n = 571). Ethnicity distribution was three patients of New Zealand European ancestry and one patient of Chinese/Pasifika ancestry. Three patients (75%) were symptomatic at presentation (spontaneous hyphema, glaucoma, and cataract), whereas one was asymptomatic but subsequently developed painful refractory glaucoma. All eyes underwent enucleation. Three eyes had primary iris biopsies with subsequent enucleation for refractory glaucoma and pain and one eye underwent primary enucleation. All cases demonstrated malignant tumor characteristics including diffuse 270 to 360-degree ciliary body ring growth pattern, epithelioid-cell type and presence of either BAP-1 expression loss or gain of MYC gene. Two cases (50%) developed distant organ metastasis - liver, parotid gland, and breast. Of those, one patient was deceased at the time of follow-up whereas one had completed treatment for metastases. Uveal ring melanoma is a rare tumor that is highly invasive and malignant. When detected, prompt definitive treatment should be advocated, and patient counselling should be given regarding the high risk of developing a painful, blind eye with increased risk of metastasis in the absence of treatment.

Understanding the improvement of sorghum starch acid hydrolysis modification by E-beam irradiation: A supramolecular structure perspective

To investigate the effect of E-beam irradiation (EBI) on acid-hydrolyzed starch, sorghum starch was pretreated with EBI (2, 4, and 8 kGy) and further hydrolyzed using hydrochloric acid (1 % and 6 % concentrations) in this study. EBI intensified acid hydrolysis corrosion on starch granule surfaces without inducing changes in the growth ring, FT-IR spectra, and crystal type (A-type). Also, EBI promoted starch degradation by acid hydrolysis, as evidenced by the R1047/1022 loss (1.071 to 1.027), the molecular weight decrease, and the chain length distribution shift (toward short A-chain). Moreover, this synergistic modification induced a starch enthalpy decrease (only 9.49 J/g) and crystallinity reduction (29.87 %), while solubility increase (34.27 %) and swelling power inhibition (only 7.65 g/g) were observed. Notably, starch digestibility was improved after synergistic modification. The obtained results broaden the processing depth of EBI in modified starch and highlight the promising application of acidolysis sorghum starch as a potential industrial starch.

Properties of Catalpa bungei (Bignoniaceae) earlywood and latewood in the same growth ring during moisture adsorption/desorption: swelling and shrinkage at the cell level

Summary In this study, Dynamic Vapor Sorption Resolution combined with a Dino-Lite Edge Digital Microscope was used to document in real-time the swelling/shrinkage behavior of earlywood and latewood cells (wood fiber and vessel) on homogeneous samples of Catalpa bungei C.A.Mey. at the microscopic scale. The results showed that the lumen and cell wall of wood fibers swelled with the increase of relative humidity and shrank with the decrease of relative humidity in the sorption cycle of 0∼95% relative humidity condition. However, vessels showed an opposite trend to the behaviors mentioned above. In any region of both types of cells, latewood cell size (area and diameter) changed more significantly. For diameter change, the change of tangential diameter was larger than that of radial diameter. In addition, in the sorption cycle, the size (area and diameter) change of any region of wood fiber and vessel showed swelling hysteresis. Compared with earlywood cells, latewood cells had a more pronounced swelling hysteretic value, and the swelling hysteretic value in the tangential direction was higher than that in the radial direction in terms of diameter. Sorption hysteresis might be one of the contributing factors to swelling hysteresis. Finally, it was found that under any relative humidity, the dimensional changes of the wood fibers and the vessels were immediately stabilized when the moisture content reached its equilibrium.

Investigating the influence of CaCl2 induced surface gelatinization of red adzuki bean starch on its citric acid esterification modification: Structure–property related mechanism

This study prepared starch with different degrees of gelatinization (10 % and 30 %) by CaCl2, and further combined with citric acid at different concentrations (10 %, 20 %, and 30 %) for esterification. The results indicated that CaCl2 induced surface gelatinization and the esterification promoted its fragmentation. This synergistic modification induced depolymerization of starch chains and a decrease in molecular weight, although starch's Maltese cross, growth rings, and crystal type remained unchanged. Moreover, the synergistic modification induces a short-range ordered structure loss and the enthalpy decrease of starch, which induce starch pasting properties decrease and solubility increase. Furthermore, the introduction of ester groups by esterification increases the resistant starch content by limiting the binding sites for digestive enzymes. In conclusion, surface gelatinization can increase active reaction sites by disrupting the starch shell structure, and serves as a potential pretreatment to enhance the deep application of esterified starch in food and pharmaceutical fields.

Energetic impact of reconstructed debris flow on the intensity and duration of growth disturbances in tree rings

A rare study on the quantitative relationship between the energetic impact of debris flows on the intensity and duration of growth disturbances of tree rings was carried out, partly due to a lack of feasible approaches and detailed field evidence. In this study, we first used a dendrogeomorphic technique to determine the age of a recent debris flow derived from historic landslide deposits at Qingyang Mountain (QYM) on the northeastern Tibet plateau. We acquired the quantitative data on the annual widths of tree rings in history and confirmed the influence of the debris flow rather than other factors (e.g., climatic events and inset outbreaking) in disturbing the growth of tree rings in a specific year. Using this approach, we determined that the age of the debris flow at QYM occurred in 1982, which was speculated to be triggered by the high monthly precipitation registered during July 1982. Subsequently, based on the boundaries of historic debris flow identified on remote sensing images before and after 1982 and the depth-integrated continuum model, we reconstructed the process of the 1982 debris flow and obtained the kinematic energy of the debris flow impacting the sampled trees. Based on the study, we observed that two growth disturbance patterns of tree rings influenced by the reconstructed 1982 debris flow were revealed, including growth suppression and asymmetric growth. We obtained a raw logarithm relationship between duration (i.e., lasting time for the disturbed tree rings to recover the initial width) and intensity of growth disturbances (i.e., growth suppression ratio of disturbed tree rings). We concluded that there is a negative exponential relationship between the simulated kinematic energy of debris flow impacting the disturbed trees and the time to recover the initial width of corresponding tree rings.

No evidence that coring affects tree growth or mortality in three common European temperate forest tree species

Tree cores are a highly valuable scientific resource. Annual growth ring data can, for example, improve our understanding of climate change impacts and effects of environmental pollution, allow for better annual estimations of tree growth patterns and carbon storage, and help quantify dynamics and changes in forest ecosystems. The value of coring trees for research has been weighted against concerns around the potential harm coring might cause to trees. To date, there is indeed limited research accurately quantifying the potential effects of coring on tree growth and only a handful of studies assessing its influence on mortality. Consequently, many European long-term forest inventorying and monitoring programs are concerned that tree coring might bias the repeated tree measurements in permanent plots, which they rely on for assessments of states and changes of forests. In this study, we assessed the effects of tree coring on the growth and mortality of three widespread European tree species approximately 10 years after they were cored. We used repeated tree measurements from permanent research sites in Switzerland and Ukraine. In Switzerland, we assessed 35 cored and 159 uncored Norway spruce (Picea abies) trees as well as 147 cored and 332 uncored silver fir (Abies alba) trees. In Ukraine, we assessed 348 cored and 6′611 uncored European beech (Fagus sylvatica) trees. We found no statistical evidence that coring negatively affected the growth or mortality of the three tree species assessed. Although we cannot rule out subtle effects on tree health and wood quality, our findings do not provide any evidence that coring affects or biases repeated measurements (such as DBH measures and recording of mortality) performed on the investigated tree species. Tree coring could therefore be considered more often for routine incorporation, particularly in long-term forest inventorying and monitoring programs and initiatives.

A 3D multi-scale hygro-mechanical model of oak wood

A multi-scale framework is proposed for the prediction of the macroscopic hygro-elastic properties of oak wood. The distinctive features of the current multi-scale approach are that: (i) Four different scales of observation are considered, which enables the inclusion of heterogeneous effects from the nano-, micro-, and meso-scales in the effective constitutive behavior of oak at the macro-scale, (ii) the model relies on three-dimensional material descriptions at each considered length scale, and (iii) a moisture-dependent constitutive assumption is adopted at the nano-scale, which allows for recovering the moisture dependency of the material response at higher scales of observation. In the modeling approach, oak wood is assumed as homogeneous at the macro-scale. The meso-scale description considers the cellular structure of individual growth rings with three different densities. At the micro-scale, the heterogeneous nature of cell walls is described by the characteristics of the primary and secondary cell wall layers. Finally, the nano-scale response is determined by cellulose micro-fibrils embedded in a matrix of hemicellulose and lignin. The oak properties at the four length scales are connected via a three-level homogenization procedure, for which, depending on the geometry of the fine-scale configuration, an asymptotic homogenization procedure or Voigt averaging procedure is applied at each level to determine the effective hygro-elastic properties at the corresponding coarse scale. In addition, the moisture adsorption isotherms at each scale are constructed from a volume-weighted averaging of the moisture adsorption characteristics at the scale below. The computational results demonstrate that the macro-scale moisture-dependent, hygro-elastic behavior of oak wood is predicted realistically, thereby revealing the influence of the material density, the micro-fibril orientation, and the hygro-elastic properties from the underlying scales. The computed macro-scale properties of oak are in good agreement with experimental data reported in the literature.

A new conifer stem, Yiwupitys elegans, from the Yiwu Jurassic Forest, Hami, Xinjiang, Northwest China

Fossil wood not only provides a comprehensive understanding of the ancient floral composition and the evolution history of wood through time, but also sheds light on the paleoclimate, paleoenvironment, and paleoecology. Permineralized conifer wood commonly occurs in the Jurassic of China; however, the detailed anatomical study has been sparsely conducted on the Jurassic wood from Xinjiang Uygur Autonomous Region (Xinjiang), Northwest China. Here, we describe a unique permineralized stem, Yiwupitys elegans Gou et Feng gen. nov. et sp. nov. from the Middle Jurassic Xishanyao Formation in Naomaohu Town of Yiwu County, Hami City, Xinjiang, Northwest China. The fossil stem is preserved with pith, primary xylem, and secondary xylem. The solid pith is heterocellular and characterized mainly by clustered or isolated secretory cells and pitted parenchymatous cells at the pith periphery. The primary xylem is mesarch showing annular, helical, and scalariform thickenings on the tracheid walls from the protoxylem to the metaxylem. The secondary xylem is pycnoxylic and exclusively composed of tracheids and parenchymatous rays. Growth rings are distinct. The secondary xylem tracheids are featured commonly by bent ends overlapping each other. They have mostly uniseriate or biseriate, or partially triseriate alternately or oppositely arranged bordered pits on the radial walls and uniseriate or biseriate bordered pits on the tangential walls. The rays are uniseriate and up to sixteen cells high. There are four to eight cupressoid pits in each cross-field, arranged in the araucarioid type. Leaf traces initiate from the pith margin and possess a single vascular strand in each trace. The anatomical structures indicate that Yiwupitys elegans has a closer affinity with conifers, although it shows few characteristics of ginkgophytes. Our study shed new light on the plant diversity of the Yiwu Jurassic Forest.

Source‐sink patterns on coffee trees related to annual climate variability: An approach through stable isotopes analysis

AbstractStable isotopic determination constitutes a useful tool to identify the processes that control the dynamics of the carbon and nitrogen flow in plants, unravelling the mechanisms of their differential investment under different environments. This work aimed to evaluate the spatiotemporal variation of source‐sink patterns of coffee trees under field conditions in response to climatic conditions through the assessment of stable isotopes. For this purpose, stems, leaves, and fruit samples from coffee trees were collected following a temporal pattern based on the region's climatic characteristics and the plant's phenology and a spatial pattern considering different parts of the canopy. The carbon and nitrogen percentage content, the C/N ratio, and the carbon and nitrogen isotopic compositions (δ13C and δ15N) were determined for all samples. The basal portion of the orthotropic branch was also considered for the isotopic analysis of the tree's growth rings. The results obtained were correlated with the climatic variables of the region through a Pearson correlation analysis (p < .05). Coffee plants showed traditional δ13C values of C3 plants. Temporal δ13C variation was associated with the different growth rates between phenological stages and the use of substrates produced at different times under different environmental conditions leading to differences in photosynthetic discrimination. Spatial δ13C variation was observed with heterotrophic tissues isotopically heavier than leaves, with a significant decrease trend in δ13C values from the top (upper third) to the bottom (lower third), associated with ecophysiological differences between the canopy, isotopic fractionation processes downstream of photosynthetic carbon discrimination, and the fixation of C from other pools. Temporal δ15N variation was associated with the precipitation rates in the region and the fertilization distribution across the tree, while the spatial variation was with the plant's nitrogen assimilation and translocation patterns. The tree growth rings isotopic analyses showed isotopic differences between growth rings of the same plant addressed by the climatic conditions, with precipitation being the primary climatic determinant influencing the fixation and discrimination against 13C. Our results highlight the importance of using stable isotope analysis as a reference point for coffee ecophysiological studies to characterize how the temporal and spatial patterns of δ13C and δ15N emerge and signal the influence of climate on the source‐sink relationship of coffee trees under field conditions.