Tree-ring characterization of Araucaria columnaris Hook and its applicability as a lead indicator in environmental monitoring

Tree-rings have frequently been used for dating of trees and to determine annual growth increments and forest dynamics, but little is known in tropical conditions about their utilization for environmental monitoring. This paper presents the results of Araucaria columnaris tree-ring characterization by wood anatomy and X-ray densitometric analysis and the determination of Pb concentration. Core samples from twelve araucaria trees were extracted from two sites exposed to air pollution due to intense traffic of vehicles and industrial activities. The tree-rings distinctly presented radial variation in early-latewood thickness and density, and characteristics of juvenile and mature wood. Anatomical and X-ray densitometric analysis were useful to delimit the tree-ring boundaries and to date the tree-rings, as well as to prove the annual formation. The lead concentration in annual araucaria tree-rings, analyzed with graphite furnace atomic absorption spectrometry, indicated the seasonal presence of the heavy metal in the environment during the 30 years studied, although the Pb did not affect tree growth.     

Curvilinear-tree-ring measurements in archaeological wood samples from X-ray computed tomography

In this paper X-ray computed tomography imaging data is used to perform nondestructive tree-ring width measurements in three archaeological wooden samples. Measurements of the curvilinear-tree-ring widths are performed using two approaches: firstly, measuring manually the distance between two points on two consecutive tree-rings along two orthogonal radii and, secondly, using a recently proposed computational approach which averages all calculated pairwise radial distances between two consecutive tree-rings along the whole tree-ring profile. The results show that the irregularity of the tree-ring shape is an important factor to be considered in performing curvilinear-tree-ring measurements. For irregular shaped tree-rings, deviations up to 1.15 mm were observed between the output of both measurement’s approaches. It is concluded that tree-ring width measurements along only two orthogonal radial rays are not always accurate enough and therefore averaging along the whole tree-ring profile is recommended.     

Lauraceae: A promising family for the advance of neotropical dendrochronology

The botanical family Lauraceae is ecologically and physiognomically very important in neotropical forests. It is one of the most frequent and distributed family both in number of individuals and species. Despite of this, we have noticed that a very few Lauraceae species have been considered in dendrochronological investigations. In order to analyze the potential of Lauraceae species in dendrochronology and to facilitate future studies we: (1) reviewed the literature on wood anatomy, cambial activity, tree growth and dendrochronology and compiled a list of species’ tree-ring features throughout the Neotropics; (2) Investigated wood anatomy, growth synchronism and climate-growth relationship using dendrochronological standard techniques in 14 species from subtropical forests of southern Brazil. Our review pointed out that the majority of Lauraceae forms distinct tree-rings in several biomes and climates in the Neotropics. Seasonal growth pattern related to water stress and to seasonal air temperature were identified in Amazonia and in subtropical high elevation sites, respectively. Time series of tree-ring width of Lauraceae species were successfully cross-dated and were already used in reconstruction of fire and vegetation dynamics. Our own dendrochronological investigations brought to light that all the 14 studied species form distinct tree-rings in seasonal or even rainforests. By analyzing time series of tree-ring width we found the same growth tendency within trees of Cinnamomum amoenum and Ocotea pulchella. Moreover, year-to-year variation in the growth time-series was linked to climate variations of temperature and precipitation, showing growth decreases when summer water stress occur. We evinced Lauraceae has distinct, synchronic and climate-sensitive tree-rings. Therefore, since Lauraceae has wide distribution and high frequency in the Neotropics and since many species become centenary, we strongly encourage the use of Lauraceae’s tree-rings in autoecology, climatology and on the reconstruction of vegetation and disturbance dynamics.     

Demystifying the age of old olive trees

Iconic to the Mediterranean landscape, the age of monumental olive trees with large trunks and unique silhouettes is often considered several centuries to millennia. Here we combine tree-ring and radiocarbon dating to show that most monumental olive trees may have maximum ages between 300 and 500 years. Our example helps disentangling the tree size-longevity conundrum in a major Mediterranean cultivated tree species and important cultural heritage.     

Nutrient concentrations of 17- year-old Pinus taeda annual tree-rings analyzed by X-ray fluorescence microanalysis

Tree-rings are sensitive indicators of soil chemical changes. X-ray fluorescence microanalysis (μ-XRF) can reveal the elemental distribution pattern along these rings. However, reports on quantitative μ-XRF methods targeted to wood analysis are scarce. This study aimed to analyze iron (Fe), manganese (Mn), calcium (Ca), potassium (K), sulfur (S) and phosphorus (P) in annual tree-rings of wood cores cut from 24 trees of 17 year-old Pinus taeda planted in soil amended with six doses of composted pulp-mill sludge (CPMS). The nutrient concentrations were accessed using calibration curves built with spiked P. taeda wood pellets. Calcium and Mn content decreased from the pith to bark direction; K and S decreased from the pith up to 3rd tree-ring and, then, increased to the bark. Iron and P slight decreased from the pith up to the 13–14th tree-ring. Calcium, K and S presented strong and positive correlation with the rainier and hotter season (r > 0.4, p < 0.05). The CPMS increased the Ca, K, Fe and S and decreased Mn and P concentration in P. taeda wood in the 2nd–5th years. Furthermore, the P. taeda annual tree-ring molar ratios of Ca/Mn and K/Ca were good indicators of soil-pH and wood cambium activity. The μ-XRF methodology, as non-destructive method of nutrient concentration analysis in tree-rings, revealed potential uses in monitoring soil fertilizer treatments.     

Response of Forest Trees to Increased Atmospheric CO 2

The CO ₂ fertilization hypothesis stipulates that rising atmospheric CO ₂ has a positive effect on tree growth due to increasing availability of carbon. The objective of this paper is to compare the recent literature related to both field CO ₂ -enriched experiments with trees and empirical dendrochronological studies detecting CO ₂ fertilization effects in tree-rings. This will allow evaluation of tree growth responses to atmospheric CO ₂ enrichment by combining evidence from both ecophysiology and tree-ring research. Based on considerable experimental evidence of direct CO ₂ fertilization effect (increased photosynthesis, water use efficiency, and above- and belowground biomass), and predications from the interactions of enriched CO ₂ with temperature, nitrogen and drought, we propose that warm, moderately drought-stressed ecosystems with an ample nitrogen supply might be the most CO ₂ responsive ecosystems. Empirical tree-ring studies took the following three viewpoints on detecting CO ₂ fertilization effect in tree-rings: 1) finding evidence of CO ₂ fertilization effect in tree-rings, 2) attributing growth enhancement to favorable climate rather than atmospheric CO ₂ enrichment, and 3) considering that tree growth enhancement might be caused by synergistic effects of several factors such as favorable climate change, CO ₂ fertilization, and anthropogenic atmospheric deposition (e.g., nitrogen). At temperature-limiting sites such as high elevations, nonfindings of CO ₂ fertilization evidence could be ascribed to the following possibilities: 1) cold temperatures, a short season of cambial division, and nitrogen deficiency that preclude a direct CO ₂ response, 2) old trees past half of their maximum life expectancy and consequently only a small increase in biomass increment due to CO ₂ fertilization effect might be diminished, 3) the elimination of age/size-related trends by statistical detrending of tree-ring series that might remove some long-term CO ₂ -related trends in tree-rings, and 4) carbon partitioning and growth within a plant that is species-specific. Our review supports the atmospheric CO ₂ fertilization effect hypothesis, at least in trees growing in semi-arid or arid conditions because the drought-stressed trees could benefit from increased water use efficiency to enhance growth.     

Dendrochronology and dendroclimatology of yew in Poland

This study concerns dendrochronology and dendroclimatology of yew growing in Poland. The yew (Taxus baccata L.), a long-lived, slow-growing tree, is regarded as a species threatened with extinction. The eastern boundary of its range transects Poland. The analyses were performed on 34 yew populations which are protected as parts of nature reserves, as nature monuments, or which are planned to be protected. Samples were collected using Pressler borer from a total of 774 trees yielding 1307 profiles. Classical dating techniques (including cross-dating method) were subsequently used to reconstruct 34 local chronologies. Average tree-ring width was 0.84 mm and ranged from 0.27 to 1.47 mm. For most stands, the age of the yew trees is overestimated. The studied populations most frequently are 100–200 years old, and the oldest yew trees in Poland are growing in the KS population (age estimated at 500–600 years). Average tree-ring width was found to be strongly dependent on the chronology length/tree age. The 674 pointer years calculated for the local chronologies served as a basis for determining pointer years for the entire study area. Negative years include: 1862, 1865, 1917, 1927, 1940, 1947, 1956, 1963, 1969, 1976, 1979, 1993, 1996, and 2003. Positive years are: 1884, 1914, 1916, 1965, 1977, 1988, 1997, and 2007. Analysis of weather conditions in those years demonstrated a strong relationship between tree-ring width and air temperature in winter, pre-spring, and early spring. Higher-than-average temperatures during those seasons correlate positively with yew tree-ring width. Response function analysis performed for local and regional chronologies point to a dominant role of air temperature in December of the year preceding growth and in January, February, and March of the current year (linear relationships). June precipitation is an additional factor affecting tree-ring width in some areas of northern and northwestern Poland: the higher the precipitation, the wider the tree-rings. The results obtained, particularly those concerning growth-climate relationships and dendroclimatic regionalisation, can be used in the on-going programme of yew restitution in Poland.     

Detecting Coppice Legacies from Tree Growth

In coppice-with-standards, once a common type of management in Central European lowland forests, selected trees (standards) were left to grow mature among the regularly harvested coppice stools to obtain construction wood. After the underwood was harvested, the forest canopy opened rapidly, giving standard trees an opportunity to benefit from reduced competition. Although this silvicultural system virtually disappeared after WWII, historical management cycles can still be traced in the tree-rings of remaining standards. Our research aims at answering the question whether tree-ring series of standard trees can be used to reconstruct past management practices. The study was carried out on 117 oak standard trees from five sites situated in formerly coppiced calcareous oak-hornbeam and acidophilous oak forests in the Bohemian Karst Protected Landscape Area, Czech Republic. The evaluation was based on the analysis of growth releases representing the response of the standards to coppicing events, and comparison to the archival records of coppice events. Our results showed that coppicing events can be successfully detected by tree-ring analysis, although there are some limitations. Altogether 241 releases were identified (49% of major releases). Large number of releases could be related to historical records, with the major ones giving better results. The overall probability of correct detection (positive predictive power) was 58%, ranging from 50 to 67%, probability for major releases was 78%, ranging from 63 to 100% for different sites. The ability of individual trees to mirror past coppice events was significantly affected by competition from neighboring trees (their number and the sum of distance-weighted basal areas). A dendro-ecological approach to the study of forest management history can serve as an input for current attempts of coppice reintroduction and for conservation purposes.     

Climate-growth response of Chinese white pine (Pinus armandii) at different age groups in the Baiyunshan National Nature Reserve,central China

Climate-growth response of trees at different age groups is less studied in humid regions of central China. In this study, we divided Pinus armandii ring-width series collected from the Baiyunshan National Nature Reserve of central China into young and old age groups based on the Hierarchical cluster analysis. Chronology statistics indicate that mean sensitivity (M.S.), signal-to-noise ratio (SNR), and expressed population signal (EPS) are higher in the old age group than that in the young age group. Meanwhile, there is are growth difference between the two age groups during their common period 1966–2014. Trees in the old age group exhibit significant decadal (∼10-year) cycles in the 1960s–1980s, while the 2–3-year cycles are more pronounced for the young age group. Correlation analysis between tree-rings and climate factors shows that the old trees generally contain more climatic information and are more sensitive to temperature, precipitation and moisture variability than the young trees, consistent with the chronology statistics. Our findings highlight the importance of considering the “juvenile effect” of young trees on tree-ring based climate reconstructions in the area.     

基于树木年轮径切特征的卷积神经网络树种识别

卷积神经网络可以通过树木年轮样本构造特征图像实现物种识别的自动化。本研究通过建立树木年轮样本构造特征图像集,选用LeNet、AlexNet、GoogLeNet和VGGNet 4个卷积神经网络模型,实现基于树木年轮横切面的计算机自动化树种精准识别,进而确定各模型的树种识别准确率,明晰不同树种在自动识别中的混淆情况,探测不同模型识别结果的差异。结果表明: 本研究训练的用于树种识别的卷积神经网络模型具有较好的可信度;4个模型中GoogLeNet模型树种识别准确率最高,为96.7%,LeNet模型识别准确率最低(66.4%);不同模型对于所选树种的识别结果具有一致性,表现为对蒙古栎识别准确率最高(AlexNet模型识别率达到100%),对臭冷杉的识别准确率最低。本研究中也存在类似结构树种的识别混淆情况。模型在科和属水平的识别准确率高于种水平;阔叶树种因其显著的结构差异容易区分,阔叶树树种的识别准确率高于针叶树。总体上,通过卷积神经网络,探测了树木年轮特征的深层信息,达到树种的精准识别,提供了一种快速便捷的自动树种初筛鉴定方法。     

Process-based modeling of tree-ring formation and its relationships with climate on the Tibetan Plateau

Response of climate warming on tree-ring formation has attracted much attention during recent years. However, most studies are based on statistical analysis, lacking understanding of tree-physiological processes, especially in the mountainous regions of the Tibetan Plateau (TP). Herein, we firstly use an updated new version of the tree-ring process-based Vaganov-Shashkin model (VS-oscilloscope) to simulate tree-ring formation and its relationships with climate factors during the past six decades. Our analyses covered 341 sampled trees growing within elevations ranging from 2750 to 4575 m a.s.l. at five sampling sites across the TP. Simulated tree-ring width series are significantly (p < 0.01) correlated with actual tree-ring width chronologies during their common interval periods. Starting dates of tree-ring formation are determined by temperature at all five sampling sites. After the initiation of tree stem cambial activity, soil moisture content has a significant effect on tree radial growth. Ending dates of cambial activity are driven by temperature over the whole study region. Simulated results indicate differences between wide and narrow tree-rings are mostly induced by soil moisture content, especially during the first half of the growing season, when effects from temperature variations are minor. Interestingly, we detected significantly (p < 0.001) increased relative growth rates due to higher soil moisture content after the year 1985 at the five sampling sites. However, the variability of mean relative growth rates due to temperature is negligible before and after that. Based on the successful application of VS-oscilloscope modeling on the high-elevation tree stands on the TP, our study provides a new perspective on tree radial growth process and their varying relationships to climate factors during the past six decades.     

Evaluation of X-ray densitometry to identify tree-ring boundaries of two deciduous species from semi-arid forests in Brazil

The presence of visible annual rings in semi-arid tropical trees may allow the application of dendrochronological methods. However, variation in water availability may cause the formation of narrow, irregular ill- or non-defined annual rings hindering the correct dating of tree-ring series. We aimed to evaluate X-ray densitometry as a method to identify tree rings of two deciduous tree species from the Caatinga forest, a semi-arid region in the northeast of Brazil, and compare with two other methods commonly used in dendrochronology, the sliding-stage micrometer and image analysis. Xylem was observed macro- and microscopically and wood anatomical features were assessed in Aspidosperma pyrifolium and Poincianella pyramidalis trees. In both species, tree-ring boundaries were identified considering intra-annual density patterns and wood anatomical features. No significant differences in tree-ring widths were found among methods. X-ray densitometry measurements showed a positive correlation with the measurements obtained with image analysis and sliding-stage micrometer in A. pyrifolium and P. pyramidalis, revealing the high reliability of the methods used. However, inter-correlation of tree-ring width series showed differences in the accuracy of crossdating across measuring methods. The maximum, mean and minimum density values were species-dependent, with mean wood density of A. pyrifolium lower than P. pyramidalis. Our results highlight X-ray densitometry as an important and complementary tool to identify tree-rings boundaries in semi-arid tree species, especially in A. pyrifolium. Along with other measuring methods, it may provide higher accuracy in dendrochronological studies in semi-arid or subtropical environments.     

Radiocarbon and dendrochronology

The radiocarbon dating method relies on calibration through an independent dating method. Dendrochronology is an ideal partner of radiocarbon, because tree-rings are close-to-perfect archives of the atmospheric ¹⁴C level, and the tree-ring time scale can be built beyond doubt with high replication. Over the past 30 years, several stages of ¹⁴C calibration data sets have been constructed from the work of tree-ring laboratories in Europe and North America. This process is outlined and the present state is documented. In turn, ¹⁴C age fluctuations, caused mainly by helio-magnetic changes, can be used to anchor floating tree-ring sections to the calendar scale with a precision of a few decades.     

Ancient juniper trees growing on cliffs: toward a long Mediterranean tree-ring chronology

Juniperus phoenicea is a tree that can grow on vertical cliff faces in dry and warm Mediterranean climate conditions. These trees are adapted to extreme growing conditions where the main constraints are verticality, compact hard limestone, and low water supply. They respond to these constraints via various specific features and high longevity. The objective of this study is to confirm whether or not their tree-rings are annual in order to specify growth strategies and accurately date these trees. Trunk morphology, anatomical wood anomalies and radial growth were analyzed on 53 trees in the Ardèche canyon. Crossdating of the ring widths using traditional dendrochronological techniques was unsuccessful, so radiocarbon dating of tree pith was used to assess tree age, and wiggle-match dating was used to test for differences between number of rings counted and radiocarbon dates. Radiocarbon dates span the period 2520–685 BP. Minimal difference between radiocarbon dates and ring counts was apparently small—missing rings occur, but not in large numbers. Tree-ring formation is annual and radial growth is low, which creates stunted old trees. Such old living trees are uncommon in the Mediterranean basin, especially at low elevation. They can provide long tree-ring chronologies back to 792–524 cal BC. Results from the radiocarbon dating indicate that accurate annual dating of these rings may be possible by crossdating. J. phoenicea growing on cliffs offer a valuable model to better understand cliff population ecology and the functional responses of trees that can live in harsh environmental conditions.     

Can tree-ring δ<Superscript>15</Superscript>N be used as a proxy for foliar δ<Superscript>15</Superscript>N in European beech and Norway spruce?

Key message

For long-term environmental investigations, tree-ring δ ¹⁵ N values are inappropriate proxies for foliar δ ¹⁵ N for both Fagus sylvatica and Picea abies under moderate N loads.

Abstract

Currently it is unclear whether stable nitrogen isotope signals of tree-rings are related to those in foliage, and whether they can be used to infer tree responses to environmental changes. We studied foliar and tree-ring nitrogen (δ¹⁵N) and carbon (δ¹³C) isotope ratios in European beech (Fagus sylvatica L.) and Norway spruce (Picea abies L.) from six long-term forest monitoring sites in Switzerland together with data on N deposition and soil N availability, as well as a drought response index over the last two decades. For both species, tree-ring δ¹⁵N and δ¹³C values were less negative compared to foliar δ¹⁵N and δ¹³C values, most likely due to recycling and reallocation of N within the tree and fractionation processes associated with the transport of sucrose and the formation of tree-rings, respectively. Temporal trends recorded in foliar δ¹⁵N were not reflected in tree-ring δ¹⁵N, with much higher variations in tree-rings compared to foliage. Soil N availability and N deposition were partially able to explain changes in foliar δ¹³C, while there were no significant correlations between environmental variables and either tree-ring or foliar δ¹⁵N. Our results suggest an uncoupling between the N isotopic composition of tree-rings and foliage. Consequently, tree-ring δ¹⁵N values are inappropriate proxies of foliar δ¹⁵N values under low-to-moderate N deposition loads. Furthermore, at such low levels of deposition, tree-ring δ¹⁵N values are not recommended as archives of tree responses to soil C/N or bulk N deposition.

     

Nondestructive tree-ring measurements for Japanese oak and Japanese beech using micro-focus X-ray computed tomography

The purpose of this study is to establish technology for utilizing images taken by micro-focus X-ray computed tomography (CT) to perform nondestructive tree-ring measurement of wooden cultural properties. This paper covers two experiments conducted using Japanese oak as a typical example of ring-porous wood and Japanese beech as a representative example of diffuse-porous wood. In the first experiment, images of thin strip specimens of Japanese oak and Japanese beech taken by micro-focus X-ray CT are compared against those taken by soft X-ray radiography, the method conventionally used in dendrodensitometry. A discussion then follows in regard to image quality and tree-ring width measurement resulting from the two methods. In the second experiment, tomograms are taken of folk art articles made of Japanese oak and Japanese beech, demonstrating that it is possible to use nondestructive means to visualize the tree-rings of three-dimensional objects. The results show that micro-focus X-ray CT offers much promise of widespread utilization in the tree-ring dating of wooden cultural properties.     

More than climate: Hydrogen isotope ratios in tree rings as novel plant physiological indicator for stress conditions

The analysis of stable carbon and oxygen isotopes in tree-rings is a widely applied tool which allows to retrieve information about past climatic conditions, as well as tree physiological responses to environmental changes. This is based on well-established mechanistic models and firm statistical relationships with climate variables. In contrast, the hydrogen isotopic signature (δ²H) of tree-rings has been reported to be poorly correlated to climate or difficult to explain, and as a consequence, hydrogen isotopes are far less utilized. However, recent plant-physiological experiments have highlighted the role of autotrophic versus heterotrophic processes affecting δ²H values, i.e. use of fresh assimilates versus stored carbohydrates, and have much improved our understanding of the role of post-photosynthetic ²H-fractionation. Using unpublished and literature δ²H data of tree-ring cellulose (δ²H_C) of 5 study sites in Europe and Asia, we systematically investigated the relationships between δ²H_C and tree-ring width (TRW), which, in contrast to previous research, could now be explained through post-photosynthetic ²H-fractionation. In most cases, these relationships were found to be negative (r² = 0.23 to 0.51, all P < 0.05) when the main growth limiting factors are precipitation and light, while in temperature-limited sites we observed a positive trend (r² = 0.14, P < 0.05). Our results suggest that, under stress conditions, trees use a surplus of carbon from reserves for wood formation. Therefore, in combination with TRW chronologies, δ²H_C may allow to infer about physiological information on stressful time periods independently of biotic and abiotic origin. Here, we discuss implications of these findings for tree-ring research, summarize them in a conceptual framework and suggest future research directions.     

Anatomical characteristics of xylem in tree rings and its relationship with environments

The anatomical traits of xylem are the characteristics of tree rings at the cellular and subcellular scales, and are often reflection of environmental signals. Studying the relationships between anatomical traits of xylem and environmental change not only provide physiological explanations to the statistics in dendroclimatology, but can also provide a new vision for studying the adaptation process and response strategies of tree growth to climate change. In this paper, with the relationships between the anatomical characteristics of xylem in tree-rings (cell chronology) and climate change as a main thread, we first outline the basic principles and mechanisms of wood anatomical features to record environmental signals, and expounded the basic methods involved in the process of xylem anatomy. Secondly, we discuss the relationship between the anatomical features of xylem and climate factors. We then propose the following as possible directions of future research based on the existing knowledge gap in the topical area: (1) to explore the temporal and spatial variations in the anatomical characteristics of xylem in tree-rings along radial and tangential directions and the relationships with environmental changes; (2) to explore the threshold of tree growth response to environmental plasticity and adaptation processes; (3) to assess the synergistic and antagonistic effects as well as the formation mechanisms of climate response among different tree-ring proxies, and to determine the specific roles and contributions of major climatic factors during different periods of tree-ring formation.     

Hydrogen and oxygen isotope ratios of tree-ring cellulose for riparian trees grown long-term under hydroponically controlled environments

Saplings of three riparian tree species (alder, birch and cottonwood) were grown for over 5 months in a hydroponics system that maintained the isotopic composition of source water in six treatments, ranging from –120 to +180‰δD and –15 to +10‰δ¹⁸O. The trees were grown in two greenhouses maintained at 25°C and at either 40 or 75% relative humidity, creating differences in transpiration rates and leaf water isotopic evaporative enrichment. The cellulose produced in the annual growth ring was linearly related to source water with differences in both slope and offset associated with greenhouse humidity. The slope of the isotopic composition of source water versus tree-ring cellulose was less than 1 for both δD and δ¹⁸O indicating incomplete isotopic exchange of carbohydrate substrate with xylem water during cellulose synthesis. Tests using the outer portion of the tree-ring and new roots were similar and showed that the tree-ring values were representative of the cellulose laid down under the imposed environmental conditions. The fraction of H and O in carbohydrate substrate that isotopically exchange with medium water was calculated to be 0.36 and 0.42 respectively, and biochemical mechanisms for these observed fractions are discussed. A mechanistic model of the biochemical fractionation events for both δD and δ¹⁸O leading to cellulose synthesis was robust over the wide range of cellulose stable isotope ratios. The experimental results indicate that both water source and humidity information are indeed recorded in tree-ring cellulose. These results help to resolve some of the disparate observations regarding the interpretation of stable isotope ratios in tree-rings found in the literature. Received: 4 January 1999 / Accepted: 12 August 1999     

Dendrochronology in the tropics using tree-rings of Pinus kesiya

The recent decade has witnessed considerable progress in the number of tree-ring studies using the tropical conifer taxa, Pinus kesiya. Several tree-ring networks have been established in less explored regions in Northeast India, Southwest China and Vietnam. The seasonal climate response of P. kesiya tree-rings has been examined and used to reconstruct temperature and soil moisture variability over the past century and augment the short instrumental records in South and Southeast Asia. In addition to standard approaches, the application of stable isotope, wood density, and blue intensity measurements indicates a significant development in P. kesiya studies. This review elaborates the future prospects of using multiple tree-ring parameters to establish discrete proxies besides tree-ring width. We recommend blue intensity as a cost-effective alternative to quantitative wood anatomy in tropical pines, and call for routine assessments of the temporal stability of climate-growth responses to identify and study potentially non-stationary climate signals. Efforts should be made towards developing extensive networks of long P. kesiya tree-ring chronologies to extend regional climate reconstructions.