Comparing automatically generated and manually measured tree-ring transects of growth trends with Hawaiian sandalwood as an example species

Tree-ring measurements are a primary quantitative tool used in numerous scientific disciplines. Some species, however, exhibit morphological complexities leading to significant uncertainty in these measurements. Hawaiian Sandalwood (Santalum paniculatum) stems, for example, often develop asymmetric growth features that hinder tree-ring measurements. These features include faint-ring boundaries and wedging rings which disappear in portions of the cross-section. In this work we a use a novel two-dimensional transect methodology and our own open-source software, svg-dendro, to analyze particularly difficult cross-sections. Our method accomplishes this by first tracing all rings by hand and automatically generating a user-specified number of transects. On average, these traced measurements had more sensitivity to tree-ring variability without losing important equivalencies with the traditional binocular stereomicroscope technique (e.g., radii, skewness) as indicated by greater mean variance for ring number, mean tree-ring width, and standard deviation. All S. paniculatum samples had ring wedging, where certain sides of the stem had many locally absent tree rings but to different intensities. The new technique allows us to analyze the shift from complete rings with little to no wedging to rings with more wedging starting between the 19th and 40th ring, where deep stem lobes begin forming. The new method also reveals the difficulty in measuring these trees, as the wedging creates multiple lobes with different visible ring counts. This research suggests that this two-dimensional methodology would be best applied to non-circular trees with fewer incomplete rings, supporting the importance of species and population selection. Overall, we have developed an efficient and flexible means to measure otherwise unmeasurable growth features in tree samples through representing tree-ring boundaries as curves and developing software to sort and map transects.     

长白山北坡不同年龄红松年表及其对气候的响应

运用树木年轮气候学方法,研究了长白山北坡红松(Pinus koraiensis)不同年龄年表特征及其与气候因子间的关系,以期揭示年龄因素对年表的潜在影响。结果表明,平均年龄为63a的红松低龄年表与平均年龄为184a的高龄年表对气候的响应明显不同:低龄红松径向生长与当年1、2月月平均温度负相关(P<0.05),同时也受到上年及当年多个月份的月平均最高温度或最低温度的影响,但与降水的相关性未达到显著水平;高龄红松径向生长则与月平均温度间的关系不明显,而与当年1、2、4、6、7、9月的月平均最高温度正相关,与当年4月、9月的月平均最低温度负相关,同时受到上年5月及当年5月月总降水量的影响。因此,年龄因素对红松年表的气候响应方面存在一定影响,且高龄年表对气候响应的敏感性更高,包含有更多的气候信息。     

Tree growth responses and resilience after the 1950-Zayu-Medog earthquake,southeast Tibetan Plateau

Understanding how severe disturbances affect forest dynamics is fundamental in ecology, conservation and management. Earthquakes of large magnitude severely impact mountain landscapes, causing strong disturbances on forests. However, it is unknown how the resilience of tree growth after strong earthquakes changes as a function of site factors as elevation. Herein, we investigated the radial-growth responses of surviving trees after the 1950-Zayu-Medog M_W 8.6 earthquake which devastated the southeastern Tibetan Plateau. We reconstructed radial growth dynamics of Abies delavayi var. motuoensis after 1950 in six sites selected along an elevational transect located in the Medog valley. Post-earthquake growth responses were detected among 60% of sampled trees in the period 1950–1955, but these responses varied depending on site elevation. Trees at the alpine treeline were less disturbed compared to those located at mid and low elevations. Severe growth suppressions, including the formation of missing rings, occurred during the first three years after the earthquake, and were stronger at low elevations. Growth releases mostly occurred after 1954. Long-term growth release, lasting more than ten years, was mainly observed at low elevations, near talus fans prone to landslides and rock falls. Growth rates returned to pre-earthquake values 45 years after the earthquake occurrence. Our results evidence how tectonic influences on tree growth depend on local factors as elevation, and demonstrate that tree resilience after severe geo-hazards is contingent on site conditions.     

Tree-ring distinctness,dating potential and climatic sensitivity of laurel forest tree species in Tenerife Island

Macaronesian laurel forests are the only remnants of a subtropical palaeoecosystem dominant during the Tertiary in Europe and northern Africa. These biodiverse ecosystems are restricted to cloudy and temperate insular environments in the North Atlantic Ocean. Due to their reduced distribution area, these forests are particularly vulnerable to anthropogenic disturbances and changes in climatic conditions. The assessment of laurel forest trees’ response to climate variation by dendrochronological methods is limited because it was assumed that the lack of marked seasonality would prevent the formation of distinct annual tree rings. The aims of this study were to identify the presence of annual growth rings and to assess the dendrochronological potential of the most representative tree species from laurel forests in Tenerife, Canary Islands. We sampled increment cores from 498 trees of 12 species in two well-preserved forests in Tenerife Island. We evaluated tree-ring boundary distinctness, dating potential, and sensitivity of tree-ring growth to climate and, particularly, to drought occurrence. Eight species showed clear tree-ring boundaries, but synchronic annual tree rings and robust tree-ring chronologies were only obtained for Laurus novocanariensis, Ilex perado subsp. platyphylla, Persea indica and Picconia excelsa, a third of the studied species. Tree-ring width depended on water balance and drought occurrence, showing sharp reductions in growth in the face of decreased water availability, a response that was consistent among species and sites. Inter-annual tree-ring width variation was directly dependent on rainfall input in the humid period, from previous October to current April. The four negative pointer years 1995, 1999, 2008 and 2012 corresponded to severe drought events in the study area. This study gives the first assessment of dendrochronological potential and tree-ring climate sensitivity of tree species from the Tenerife laurel forest, which opens new research avenues for dendroecological studies in Macaronesian laurel forests.     

Tree-ring growth and stable isotopes (13C and 15N) detect effects of wildfires on tree physiological processes in Pinus sylvestris L.

Forest fires may alter the physiological and growth processes of trees by causing stress in trees and modifying the availability of soil nutrient. We investigated if, after a high-severity fire, changes in tree-ring growth can be observed, as well as changes in the nitrogen and carbon isotope composition of tree rings of surviving trees. Two wildfires that occurred in Pinus sylvestris L. stands in Northern Italy, one at the beginning and one at the end of the vegetative season, were chosen as the focus of this study. After the fires, the surviving trees showed growth suppression with very narrow tree rings or locally absent rings. The carbon isotope ratio was more negative in tree rings formed in the 5 years following fire, indicating better water supply in a situation of less competition. The nitrogen isotope ratio followed opposite trends in the two wildfire stands. In trees cored in the stand where the fire happened at the beginning of the vegetative season, there was no change in the nitrogen isotope ratio, whereas in samples collected in the other fire site, higher nitrogen isotope ratios were observed in the tree rings formed after the fire, reflecting changes in the soil nitrogen supply. Modifications in the growth and isotope composition of the fire-stressed trees disappeared from 6 to 10 years after the fire. By studying trees before and after fire, we were able to show that fire affects not only the growth of surviving trees, but also their physiological processes.     

Comparison of whole wood and cellulose carbon and oxygen isotope series from Pinus nigra ssp. laricio (Corsica/France)

Stable isotopes in tree rings have widely been used for palaeoclimate reconstructions since tree rings record climatic information at annual resolution. However, various wood components or different parts of an annual tree-ring may differ in their isotopic compositions. Thus, sample preparation and subsequent laboratory analysis are crucial for the isotopic signal retained in the final tree-ring isotope series used for climate reconstruction and must therefore be considered for the interpretation of isotope–climate relationships. This study focuses on wood of Corsican Pine trees (Pinus nigra ssp. laricio) as this tree species allows to reconstruct the long-term climate evolution in the western Mediterranean. In a pilot study, we concentrated on methodological issues of sample preparation techniques in order to evaluate isotope records measured on pooled whole tree-ring cellulose and whole tree-ring bulk wood samples. We analysed 80-year long carbon and oxygen chronologies of Corsican Pine trees growing near the upper tree line on Corsica. Carbon and oxygen isotope records of whole tree-ring bulk wood and whole tree-ring cellulose from a pooled sample of 5 trees were correlated with the climate parameters monthly precipitation, temperature and the self-calibrating Palmer Drought Severity Index (sc-PDSI). Results show that the offsets in carbon and oxygen isotopes of bulk wood and cellulose are not constant over time. Both isotopes correlate with climate parameters from late winter and summer. The carbon and oxygen isotope ratios of cellulose are more sensitive to climatic variables than those of bulk wood. The results of this study imply that extraction of cellulose is a pre-requisite for the reconstruction of high-resolution climate records from stable isotope series of P. nigra ssp. laricio.     

Evaluating the annual nature of juvenile rings in Bolivian tropical rainforest trees

Knowledge on juvenile tree growth is crucial to understand how trees reach the canopy in tropical forests. However, long-term data on juvenile tree growth are usually unavailable. Annual tree rings provide growth information for the entire life of trees and their analysis has become more popular in tropical forest regions over the past decades. Nonetheless, tree ring studies mainly deal with adult rings as the annual character of juvenile rings has been questioned. We evaluated whether juvenile tree rings can be used for three Bolivian rainforest species. First, we characterized the rings of juvenile and adult trees anatomically. We then evaluated the annual nature of tree rings by a combination of three indirect methods: evaluation of synchronous growth patterns in the tree- ring series, ¹⁴C bomb peak dating and correlations with rainfall. Our results indicate that rings of juvenile and adult trees are defined by similar ring-boundary elements. We built juvenile tree-ring chronologies and verified the ring age of several samples using ¹⁴C bomb peak dating. We found that ring width was correlated with rainfall in all species, but in different ways. In all, the chronology, rainfall correlations and ¹⁴C dating suggest that rings in our study species are formed annually.     

An organismal view of dendrochronology

An organism is the most basic unit of independent life. The tree-ring record is defined by organismal processes. Dendrochronology contributes to investigations far removed from organismal biology, e.g., archeology, climatology, disturbance ecology, etc. The increasing integration of dendrochronology into a diverse research community suggests an opportunity for a brief review of the organismal basis of tree rings.Trees are dynamic, competitive, and opportunistic organisms with diverse strategies for survival. As with all green plants, trees capture the energy in sunlight to make and break chemical bonds with the elements essential for life. These essential elements are taken from the atmosphere, water, and soil. The long tree-ring series of special interest to dendrochronology result from long-lived trees containing relatively little decayed wood. Both of those features result from organismal biology. While the tree-ring record tells us many things about local, regional, and even global environmental history, tree rings are first a record of tree survival.     

Identification,measurement and interpretation of tree rings in woody species from mediterranean climates

We review the literature dealing with mediterranean climate, vegetation, phenology and ecophysiology relevant to the understanding of tree-ring formation in mediterranean regions. Tree rings have been used extensively in temperate regions to reconstruct responses of forests to past environmental changes. In mediterranean regions, studies of tree rings are scarce, despite their potential for understanding and predicting the effects of global change on important ecological processes such as desertification. In mediterranean regions, due to the great spatio-temporal variability of mediterranean environmental conditions, tree rings are sometimes not formed. Often, clear seasonality is lacking, and vegetation activity is not always associated with regular dormancy periods. We present examples of tree-ring morphology of five species (Arbutus unedo, Fraxinus ornus, Quercus cerris, Q. ilex, Q. pubescens) sampled in Tuscany, Italy, focusing on the difficulties we encountered during the dating. We present an interpretation of anomalies found in the wood structure and, more generally, of cambial activity in such environments. Furthermore, we propose a classification of tree-ring formation in mediterranean environments. Mediterranean tree rings can be dated and used for dendrochronological purposes, but great care should be taken in selecting sampling sites, species and sample trees.     

Recent growth increase in endemic Juglans boliviana from the tropical Andes

The spatial coverage of tree-ring chronologies in tropical South America is low compared to the extratropics, particularly in remote regions. Tree-ring dating from such tropical sites is limited by the generally weak temperature seasonality, complex coloration, and indistinct anatomical morphology in some tree species. As a result, there is a need to complement traditional methods of dendrochronology with innovative and independent approaches. Here, we supplement traditional tree-ring methods via the use of radiocarbon analyses to detect partial missing rings and/or false rings, and wood anatomical techniques to precisely delineate tree-ring boundaries. In so doing we present and confirm the annual periodicity of the first tree-ring width (TRW) chronology spanning from 1814 to 2017 for Juglans boliviana (‘nogal’), a tree species growing in a mid-elevation tropical moist forest in northern Bolivia. We collected 25 core samples and 4 cross-sections from living and recently harvested canopy-dominant trees, respectively. The sampled trees were growing in the Madidi National Park and had a mean age of 115 years old, with certain trees growing for over 200 years. Comparison of (residual and standard) TRW chronologies to monthly climate variables shows significant negative relationships to prior year May-August maximum temperatures (r = −0.54, p < 0.05) and positive relationships to dry season May-October precipitation (r = 0.60, p < 0.05) before the current year growing season. Additionally, the radial growth of Juglans boliviana shows a significant positive trend since 1979. Our findings describe a new and promising tree species for dendrochronology due to its longevity and highlight interdisciplinary techniques that can be used to expand the current tree-ring network in Bolivia and the greater South American tropics.     

Growth variation in Abies georgei var. smithii along altitudinal gradients in the Sygera Mountains, southeastern Tibetan Plateau

A network of nine Smith fir (Abies georgei var. smithii) ring-width chronologies was constructed from sites ranging in elevation from 3,550 to 4,390 m above sea level (a.s.l.) in the Sygera Mountains, southeastern Tibetan Plateau. High-elevation trees had lower growth rates than did low-elevation trees. The mean tree-ring series intercorrelation (RBAR) increased with elevation. Principal component analysis identified three elevation zones (around 3,600, 3,800, and >4,200 m a.s.l.) with distinctive tree-ring growth patterns. Five chronologies with elevation >4,200 m a.s.l. were highly correlated. Overall, the initiation of tree-ring growth in Smith fir is controlled by common climatic signals, such as July minimum temperature, across a broad altitudinal range. Precipitation was not a growth-limiting factor across stands. Regardless of differences in stand elevation, topographical aspect, and tree age, the radial growth of Smith fir trees was markedly similar in response to common climatic signals, perhaps as a result of the relatively high-elevation of these forests (above 3,550 m a.s.l.) and the abundant summer monsoon rainfall. In addition, radial tree growth along the altitudinal gradients was indicative of a recent warming trend on the southeastern Tibetan Plateau.     

黄土高原南北样带尺度人工刺槐林对气候响应的敏感性分析

根据黄土高原南北样带尺度的人工刺槐林(Robinia pseudoacacia)的年轮宽度资料,分析了该地区刺槐树木生长趋势,以及刺槐年表对气候响应随降雨梯度变化规律。研究结果表明延安以北的刺槐样点(绥德、神木)年轮指数近期趋于下降,树木有生长衰退现象;而延安以南刺槐样点(延安、富县、宜君、永寿)年轮指数近期趋于上升,树木无生长衰退现象。气候响应结果表明,刺槐年表对气候响应均以延安样点最为敏感,表现年表与温度的负相关关系,以及年表与降雨和干旱指数的正相关关系,而延安以北和以南刺槐样点对气候响应敏感性均较低。黄土高原中部延安地区地处森林草原过渡带,刺槐生长对外界环境变化最为敏感,年表中气候信号也较强;延安以南地区地处森林植被带,气候条件较为适宜刺槐林生长,因而年表中气候信号较弱;延安以北地区地处草原植被带,气候条件比较恶劣,刺槐生长对干旱气候已有一定适应性特征,因而年表中气候信号也较弱。     

Scattered trees as modifiers of agricultural landscapes: the role of waddeessa (Cordia africana Lam.) trees in Bako area, Oromia, Ethiopia

Scattered trees in general and scattered waddeessa (Cordia africana Lam.) trees in particular are very common across the agricultural landscapes in Oromia, Ethiopia. A study on this scattered waddeessa trees commonly growing on farmers' agricultural fields was conducted at Bako in western Oromia, Ethiopia with the objective of assessing their role in modifying the soil properties in the agricultural landscape. Soil samples from surface layers (0–10 cm) were taken at three concentric transects (0.5, 2 and 4 m) around the tree and compared with soil samples from the adjacent open areas (15 m distance from the tree), and then analysed following the standard procedures. Results showed that scattered waddeessa trees significantly modified the overall properties of the soil in the agricultural landscape of Bako area. But soil texture was not affected, indicating that it is more related to parent material than the tree influence. Hence, the soil patches observed under these waddeessa trees can be important local nutrient reserves that may influence the rural agricultural landscape. They also play an important role in generating local household income from the sale of products and conserving biodiversity by providing habitats and resources that are otherwise absent or scarce in agricultural landscape.     

What tree rings can tell us about the competition between trees and lianas? A case study based on growth,anatomy, density,and carbon accumulation

In tropical forest, landscape fragmentation and the consequent degradation of disturbed forests increase the incidence of light and dry hot winds, causing a disturbance on natural regeneration. Under these conditions, lianas (woody vines) development is stimulated instead of other species, which are more suited to mature forest and under less influence of the edge effect. For this, lianas colonization is an important variable for assessing the disturbance level of a forest. In this context, it becomes important to understand the nature of the competitive relationships between hyper-abundant lianas and ring growth of the host trees. Here, we selected trees with occupation or absence of lianas from two tropical species – Pinus caribaea var. hondurensis (Caribbean pine) and Tectona grandis (teak) – localized in a semideciduous forest fragment in southeastern Brazil, aiming to compare growth, climatic response, anatomy (vessels and intra-annual density fluctuations), wood density and carbon, by tree-ring analysis. The results showed that the lianas caused a change in tree-ring anatomy of host trees in last 10 years, mainly. We observed that trees occupied by lianas had a decrease the radial growth and carbon in the two species, an increase of the vessels size in teak and a decrease of the IADF frequency in Caribbean pine. In teak, the climate-tree relationship indicated that trees with lianas had lower response to rainfall and higher response to temperature in the summer (rainy and hottest period); in Caribbean pine, we observed that trees with lianas had a 2-month delay in the radial growth response to rainfall in the dry season. In the teak group, we observed that host trees had higher wood density values than liana-free tree in the outer rings, and the opposite was showed for pine. These findings show that tree-ring growth of host trees are a strong bioindicator of forest disturbance caused by aggressive colonization of lianas. We believe that these methods are applicable to future studies relating to the effects of habitat fragmentation and forest degradation on biodiversity and ecosystem services, particularly in the context of global climate change.     

A 781-year oak tree-ring chronology for the Middle Ages archaeological dating in Maramureș (Eastern Europe)

From 1997 to the present, a sustained project in the Maramureș region in Romania was completed with the construction of a 781-year oak tree-ring chronology. A total of 395 samples from living trees and 429 from archaeological wood were analysed with dendrochronological methods. The study aimed to provide the scientific community with a new oak chronology that could be applied in dendroarchaeology, dendroclimatology and dendroecology studies and also for interpreting past socio-economic events. Furthermore, we studied the number of sapwood rings and the growth pattern for different time periods. The chronology covered the continuous period of A.D. 1236‒2016. From the 824 samples collected, we separated 271 tree-ring series into a new chronology (A.D. 1406–2016), which fulfilled all the criteria necessary to reconstruct past climate and environmental changes. The resulting new tree-ring chronology indicated robust signal series intercorrelation (r = 0.55) and an average mean sensitivity of 0.21. Based on an analysis of the sapwood, we recommend estimating a number between 8 and 32 rings to the date of final ring for 95% confidence range of mean on the for felling in the Maramureș region. Additionally, we observed that the number of sapwood rings was not correlated with altitude or oak tree species.     

Recent decline of high altitude coniferous growth due to thermo-hydraulic constrains: evidence from the Miyaluo Forest Reserve,Western Sichuan Plateau of China

Tree growth decline has been reported in many places around the globe under the context of increasingly warming climate, and strengthening drought intensity is detected to be the primary factor for such decline, particularly in northern forest sites, as well as arid and semi-arid areas. Yet, the forest growth decline in high altitude, high mountain sites certainly merits investigation. Here, we reported faxon fir (Abies fargesii var. faxoniana) forest growth decline (slope = -0.64) at the tree line (4150 m above sea level) in Miyaluo Forest Reserve (MFR) at the Western Sichuan Plateau, southwestern China since 2000. We investigated the cause of tree growth decline by applying dendrochronological approaches. We took tree-ring samples from fir trees at the tree line and developed tree-ring width (TRW) chronology. The tree growth – climate relationship analysis showed that maximum temperature (Tmax) was the primary factor limiting the radial growth of fir trees in the investigated area. The moving correlation analysis indicated the strengthening positive influence of Tmax, spring precipitation, and cloud cover during winter and monsoon period on radial growth since 2000s. Our results have shown that both thermal and hydraulic constrains accounted for the radial growth decline of fir trees at the tree line of MFR in the western Sichuan Plateau.     

Inverse effects of recent warming on trees growing at the low and high altitudes of the Dabie Mountains,subtropical China

Understanding how tree rings of different species at different elevations respond to climate, and whether their relationship is stable over time is crucial not only for credible palaeoclimatic reconstructions, but also for better awareness of forest growth dynamics and therefore making scientific management decisions against a background of global warming. In this work, six tree-ring chronologies of Pinus taiwanensis at three sites from 800 to 1550 m above sea level (asl), and Pinus massoniana at three sites from 500 to 650 m asl were developed in the Dabie Mountains (DBS), subtropical China. In recent decades, only P. taiwanensis at 1550 m asl showed a positive growth-trend. Both P. taiwanensis at 800 m asl and three low-altitude P. massoniana at 500–650 m asl showed negative growth trends. Climate-growth relationship analyses revealed that 1) temperature was the dominant climatic factor that controlled tree-ring growth in DBS. It exerted most influence on trees growing at the lower and upper limit, than for trees growing at altitudes from 650 to 1450 m asl. Only precipitation in October positively influenced tree growth of P. massoniana at all three sites and P. taiwanensis at 800 m asl; 2) There was a shift in temperature’s impact on trees, that was from significantly negative relationship at the four lower altitudes, mainly for the current growing-season, to significantly positive relationship in previous February–July period at the highest altitude. The higher the altitude, the more significant the lag effect of temperature on trees; 3) The influence of temperature on tree growth at most altitudes were variable over time. The positive influence of temperature on trees at 1550 and 1450 m asl was comparatively stable during the early period of instrumental records. It strengthened evidently since the early 1990s, which is coincidental with the timing of the evident temperature increase in DBS. On the contrary, the negative impacts of temperature on tree growth at 800, 650 and 500 m asl had weakened since the early 1990s. Besides the increase of water use efficiency of trees, we speculated that the increasing influence of precipitation in May and July weakened the relationship between temperature and tree rings at low altitudes. This work points out that the upper and lower limits of forest in DBS offer the preferred locations for future sampling in climate reconstruction, but the stability of tree growth and climate over time should be considered. Moreover, forest management should give priority to altitude factors, in addition to tree species representation.     

Dendroecology in the tropics: a review

Over the last decade the field of tropical dendroecology has developed rapidly and major achievements have been made. We reviewed the advances in three main themes within the field. First, long chronologies for tropical tree species were constructed which allowed climate reconstructions, revealed sources of climatic variation and clarified climate–growth relations. Other studies combined tree-ring data and stable isotope (¹³C and ¹⁸O) measurements to evaluate the response of tropical trees to climatic variation and changes. A second set of studies assessed long-term growth patterns of individual trees throughout their life. These studies enhanced the understanding of growth trajectories to the canopy, quantified autocorrelated tree growth and yielded new estimates of tree ages. Such studies were also used to reconstruct the disturbance history of tropical forests. The last set of studies applied tree-ring data to growth models. Tree-ring data can replace diameter measurements from research plots, provide additional information to construct population models, improve timber yield models and validate model output. Based on our review, we propose two main directions for future research. (1) An evaluation of the causes and consequences of growth variation within and among trees and their relation to environmental variation. Studies evaluating this directly contribute to improved understanding of tropical tree ecology. (2) The simultaneous measurement of widths and stable isotope fractions in tree rings offers the potential to study responses of trees to climatic change. Given the major role of tropical forests in the global carbon cycle, knowing these responses is of high priority.     

The potential of intra-annual density information for crossdating of short tree-ring series

The crossdating of tree-ring series is typically based on tree-ring width sequences, which is a crude abstraction of the growth signal stored in tree rings. In contrast, intra-annual wood density data allows a much more detailed comparison of wood growth processes and new measurement techniques scale well to measure large amounts of samples. Thus, chronologies of intra-annual densitometric curves can be built. Here, we investigate to what extent intra-annual wood density information can improve crossdating. We evaluate different approaches on a data set of Norway spruce trees (Picea abies) and compare the results to standard methods that are based on ring width or maximum density. Our results show that intra-annual densitometric data indeed increases crossdating success rate notably for short tree ring series that cover less than 25 years.     

Xylem traits of peatland Scots pines reveal a complex climatic signal: A study in the Eastern Italian Alps

Long-term climate reconstructions are frequently based on tree-ring high-resolution proxies extracted from subfossil peatland trees. Peatlands are peculiar ecosystems characterized by high moisture in the upper soil part which creates a harsh living environment for trees. The climate mostly indirectly influences tree growth determining seasonal variations in the water table level. Within this framework, the aim of this study was to investigate climate responses of trees (Pinus sylvestris L.) growing inside and outside a Southern Alpine peat bog, by using tree-ring and wood anatomical traits (e.g. tracheid number and dimension, cell-wall thickness). Our results showed differences in the xylem structure and climate signal recorded by peatland and mineral soil trees. Peatland trees were characterized by narrow rings and tracheids with thinner cell wall. Summer temperature and precipitation were the major drivers of xylem formation in peatland trees. At intra-annual level wood anatomical traits revealed a complex within-ring signal during the growing season. The multi-parameters approach together with the high-resolution gained by using tree-ring sectors allowed us to obtain new detailed information on the xylem development of peatland trees and climate drivers that influenced it.