Accurately dating ancient mining activities remains a major challenge, particularly where radiocarbon chronologies lack precision. This study aims to refine the chronology of medieval silver–lead exploitation at the Vallauria mine (Alpes-Maritimes, France) through an integrated dendrochronological and dendroanthracological approach.The analysis focuses on charcoal remains recovered from the “Absides” sector, a mining area located at the south-western end of the medieval extraction front. These remains correspond to in situ residues of firesetting activities used for ore extraction. Several hundred charcoal fragments, mainly conifers (Larch/Spruce and Silver fir), were analysed. Tree-ring series were measured and grouped into eight mean chronologies, which were cross-dated with regional reference datasets to establish terminus post quem (TPQ). In parallel, a dendroanthracological protocol was applied to distinguish branch wood from trunk wood based on ring-width distributions derived from modern reference samples. This distinction enabled the estimation of missing rings in branch fragments using a maximum branch age of 125 years, providing terminus ante quem (TAQ).The results yield several TPQs and TAQs, indicating that the main mining phases occurred between the 12th and early 13th centuries, with a possible extension into the early 14th century. Although some TPQs remain uncertain due to moderate correlations and the specific growth patterns of European larch, combining TPQ and TAQ significantly refines chronological resolution compared to radiocarbon dating alone. The dendroanthracological analysis shows a predominant use of trunk wood, alongside variable contributions of branch wood within firesetting piles suggesting the full exploitation of harvested trees.Despite methodological limitations, this study highlights the strong potential of combining dendrochronology and dendroanthracology to improve the temporal resolution of mining activities and better understand past wood-use practices.
Forest is the largest terrestrial carbon sink on land, and assessing tree growth stability (growth variability, resistance and resilience) profoundly influences carbon sequestration potential. However, information regarding the spatial and temporal variations in growth stability across natural and planted forests remains limited. We compared interannual growth variability, drought resistance and resilience between natural and planted Chinese pine (Pinus tabuliformis) stands in northern China during the period of 1979–2018, and investigated the influence of climate (mean and variability) on growth variability. No significant difference in growth variability between forest types, however, planted forests exhibited significantly higher resistance and resilience of one-year drought events. Temporally, growth variability in planted forests significantly increased during 1999–2018 compared with 1979–1998. Furthermore, growth variability was significantly negative with precipitation and aridity index in both forest types. These findings provide valuable insights into the response of Chinese pine to climate change and have important implications for the forest management of Chinese pine under future climate change.
Blue rings (BRs) are wood anatomy anomalies that present great potential in identifying cold spells during the growing season. In this study, we investigated the effect of temperature anomalies on the occurrence of two types of BR in Pinus sylvestris at its northern distribution limit in Norway. Of the 3,508 individual tree rings from 1727 to 2022 analysed, we identified 206 BRs from a span of 85 years, the oldest formed in 1730. We distinguished two types of BR: Type A with normal earlywood and latewood ending with a thin blue layer; and Type B with the entire latewood zone replaced by earlywood-like tracheids. Our results demonstrate that the two types have a common climatic trigger – a cool spring and autumn. However, Type A is more linked to tree-ring width, whereas Type B is associated more closely with tree ontogeny and local environmental constraints. Although we observed the formation of BRs even in old trees, we found that they formed more frequently in young specimens. We showed that while the short-term cyclical drivers of Type A remained persistent, the climatic or environmental drivers associated with Type B gradually diminished under climate change. Our study demonstrates that the differentiation of BRs into types can contribute to a better understanding of their driving factors; however, detailed intra-annual phenological and xylogenetic monitoring will be crucial to achieve further insights.
Shrub-ring analysis is increasingly used to assess climate-growth relationships in Arctic and alpine ecosystems. However, manual ring measurement remains labor-intensive and time-consuming, limiting the scale of ecological inference. To address this challenge, here we evaluated the Iterative Next Boundary Detection (INBD) deep learning method for automated ring detection using a new dataset of 50 manually annotated Salix glauca cross-section images from western Greenland. The model achieved intermediate performance, successfully detecting rings in morphologically clear samples but showing limited accuracy in more complex cases. We further evaluated three image resizing strategies and found that normalizing images to a fixed largest dimension of 1504 pixels improved segmentation accuracy and reduced training time compared to fixed downsampling approaches. We compared ring traces from automated and manual delineations, calculating basal area increment (BAI) from both approaches, along with six additional metrics derived from the manual ring traces. Growth patterns and ring counts from automated delineations were generally consistent with manually traced rings. Correlation analyses showed positive relationships between summer temperature and growth, with BAI (both automatic and manual) showing non-significant trends. In contrast, most one-dimensional metrics exhibited significant positive correlations, highlighting the potential influence of measurement approach on inferred climate sensitivity. Linear mixed-effects models further revealed consistent, significant positive relationships between shrub growth and mean summer temperature across all metrics, with the model based on automatically derived BAI explaining the largest proportion of variance. Our findings highlight both the potential and current limitations of the INBD method for automated shrub ring analysis in Salix glauca. Despite existing accuracy issues, the method can currently produce ecologically meaningful ring delineations and growth patterns. With species-specific training, refinement, and further testing, automated ring detection can accelerate data extraction from shrub rings and expand dendrochronological research in cold-climate regions.
The spatial coherence of the Asian monsoon system is a key assumption in regional dendroclimatology, however its validity across the equator remains largely untested. We investigate the potential for Mainland–Maritime hydroclimatic decoupling by comparing tree-ring growth of Tectona grandis from Umphang, Thailand (1843–2022), and Wanagama, Indonesia (1956–2023). Using standard dendrochronological techniques and bootstrapped Pearson correlations in R, we developed robust chronologies of total ring width, earlywood, and latewood (EPS > 0.96). Despite shared monsoonal climates, the overlapping period (1956–2022) shows a clear functional disconnect across the equator, with no significant correlation between the chronologies (r = 0.02). Spatial teleconnection analyses reveal two contrasting climatic regimes. The maritime Indonesian signal is strongly linked to ENSO (r = −0.410, p < 0.001) and the Indian Ocean Dipole (r = 0.310), reflecting a demand-driven system controlled by atmospheric circulation and dry-season moisture deficits. Conversely, the mainland Thailand signal exhibits less ENSO influence, relating instead to pre-monsoon moisture availability and Pacific Decadal Oscillation variability (r = −0.204, p < 0.10), indicating a supply-driven growth regime. The Monsoon Relay test (r = 0.04) confirms that the biological response to seasonal monsoon progression operates independently across the mainland and maritime sectors. Overall, these results challenge a spatially unified Monsoon Asia system. Instead, they reveal an equatorial hydroclimatic boundary where mainland and maritime forests respond to different ocean–atmosphere forcing mechanisms. This finding underscores the importance of site-specific, multi-network dendroclimatic frameworks for accurately reconstructing regional hydroclimate across the Southeast Asian corridor.
This work provides a novel, multi-proxy approach employing dendroecological techniques, to reveal patterns of species recruitment and population dynamics for long-lived species. In doing so it informs our understanding of the impact of disturbance regimes on plant community dynamics. Using the threatened, fire sensitive understorey tree Persoonia arborea as a case study, this study combined bomb-pulse radiocarbon dating, tree-ring analysis, and field surveys to reconstruct recruitment and persistence in response to disturbance from wildfire and commercial forest harvesting. We demonstrate rings are broadly annual but irregular with occasional missing or false rings reflecting the wandering lobate growth in the species. Growth declines with age, providing further support for the use of non-linear growth models for long-lived species. Reconstructing age using tree rings is a cost-effective option within the confines of an 18% error rate. Radiocarbon dating was the most accurate (CV = 5%) but also most expensive. The age-size (diameter at breast height) allometry was less precise (CV =22%) but is useful for rapid assessment of tree age. Using the best age-size models to reconstruct age distribution for over 5500 field observations, we demonstrate that fruiting probability increases with age, reaching 50% at 15 years and 90% at 46 years. Flowering peaks from January to March and fruit production peaks from August to October. Persoonia arborea recruits in pulses after fire, is killed in high severity fire but can persist at lower density within the footprint of light to moderate fire severity resulting in multi-age cohorts. The species can regenerate in the absence of fire and can regenerate continuously after clearfelling with a wide range of tree ages observed within the footprint of older (1970–2000) logging coupes. In this way, we demonstrate the utility of fire sensitive species in reconstructing disturbance history extends beyond the most recent fire.
Forest ecosystems are increasingly vulnerable to climate change, particularly through rising temperatures and more frequent extreme droughts. Understanding how environmental heterogeneity shapes tree growth and drought responses is essential for predicting forest dynamics under these changing conditions.We investigated how fine-scale environmental heterogeneity, defined by micro-environmental (topo-edaphic) differences, modulates radial growth, climate sensitivity and drought resilience in Araucaria araucana, a keystone and endangered conifer native to Patagonian forests. We analyzed tree-ring series from 156 individuals across four forest stands in Argentina, spanning a broad regional mesic–xeric gradient and contrasting within-site environmental conditions. Growth sensitivity to drought was assessed using dendrochronological techniques, correlation analyses with atmospheric and soil moisture drought indices, and resistance and resilience metrics, the latter calculated using flexible, tree-specific recovery windows.Micro-environmental variability exerted a strong influence on growth patterns: within sites, trees in mesic units exhibited higher growth rates, while those in xeric units showed reduced radial growth. Growth–environment (climate and soil moisture) relationships varied across the regional gradient: in the wetter western range, growth was influenced by both atmospheric and edaphic conditions, while towards the drier eastern limit, atmospheric drivers predominated. Regardless of large-scale geographical distribution, trees in xeric micro-environments consistently showed greater sensitivity to climatic and soil moisture variability than their mesic counterparts.Drought responses reflected interacting effects operating across spatial scales. Micro‑environment determined baseline resistance and resilience, whereas the influence of climatic conditions before, during, and after drought events was contingent upon the macro‑regional context, as evidenced by the distinct response patterns of micro-environmental units located in the western (mesic) versus the eastern (xeric) regions. The flexible resilience index developed in this research proved more sensitive to inter-individual variation in post-drought recovery than traditional fixed-window metrics, suggesting its potential as a complementary metric in resilience studies.
Dendroecology offers insights into plant species responses to abrupt and long-term shifts in environmental conditions, but studies are predominantly focused on trees in forest ecosystems. This systematic literature review examines the prevalence and patterns of dendroecological studies conducted outside forest habitats. Utilizing the PRISMA framework, we systematically searched the Web of Science and identified 59 relevant publications encompassing 217 sampling sites across 26 countries. The studies showed a strong geographic bias towards temperate and cold regions, primarily in the Northern Hemisphere, and a scarce research cover from arid regions, where TOFs are highly present. We found a focus on urban and agricultural settings, and a predominant emphasis on Pinaceae, revealing a lack of knowledge on a broader set of TOF species. Tree-ring width was identified as the primary method for assessing climate-growth relationships in the studies, while wood anatomy, wood density, and stable isotopes were used less frequently. Our findings indicate a strong positive correlation between precipitation and tree growth across various climates, while temperature exhibited mixed effects. The underrepresentation of studies in the Tropics and the Southern Hemisphere, the taxonomic composition of TOF dendroecology, and the predominance from ring width as a parameter to study growth highlight a critical bias in current knowledge. To advance TOF dendroecology, future research must prioritize sampling sites where TOFs are highly present, obtaining metadata related to management and stand origin, and adopting a multi-parameter approach to understand climate-growth relationships to create a more comprehensive framework for understanding global tree-growth dynamics.
Climate change is increasing stress on forest ecosystems in arid and semi-arid regions, where tree growth is highly climate-sensitive. We examined climate controls on the tree-ring width (TRW) of Persian juniper (Juniperus polycarpos) at two semi-arid mountain sites in northeastern Iran, Qorkhūd Mountains and Hezar Masjed Mountain. The chronologies span 1231–2023 CE at Qorkhūd (793 years), and 1523–2021 CE at Hezar Masjed (499 years). Based on the EPS threshold (> 0.85), the reliable reconstruction intervals begin in 1612 CE and 1780 CE, respectively. Climate–growth analyses using CRU TS 4.03 and local synoptic records showed that Qorkhūd TRW responds positively to previous June–current May precipitation and negatively to temperature over the same period, whereas Hezar Masjed growth is mainly limited by previous October–current May precipitation. Linear regression models, validated by leave-one-out cross-validation, reconstructed precipitation for 1612–2022 at Qorkhūd (410 years; R² = 0.41) and 1786–2020 at Hezar Masjed (235 years; R² = 0.33). Both reconstructions show strong interannual to multi-decadal hydroclimatic variability. Synchronous dry years, including 1917, 2001, and 2008, and the wet year 1981, indicate regionally coherent precipitation anomalies. Recent decades include several of the most pronounced wet and dry events in the reconstructions, highlighting the occurrence of strong hydroclimatic extremes during the late twentieth and early twenty-first centuries. At Qorkhūd, the reconstruction also captures the observed calibration-period precipitation decline. Exploratory analyses indicate temporally variable links with North Atlantic indices, including NAO and AMO. These records provide a long, multi-site hydroclimatic context for northeastern Iran.
High mountain ecosystems are especially sensitive to climate change. The treeline is expected to shift to higher elevations due to rising temperatures. However, temperature and precipitation sensitivities of tree species within treeline ecotones may differ. Using a dendroclimatological approach, we compared the tree growth-climate relationships of Abies spectabilis and Rhododendron campanulatum, two of the dominant treeline-forming species in Central Himalayan treeline ecotones. We correlated tree ring widths with monthly and seasonal climate data, including the Standardized Precipitation-Evapotranspiration Index (SPEI). We found contrasting climate sensitivities between these species. Moving and evolving correlation analyses revealed that Abies spectabilis showed a strong negative response to spring temperatures (March-May) in recent decades. In past decades, spring growth-climate relationships were inconsistent. Responses to precipitation and SPEI suggest that the shifts to stable negative spring temperature responses are linked to rising drought stress. In contrast, the growth-climate relationships of Rhododendron campanulatum remained more stable over time, with weaker signs of drought stress, indicating greater resilience to climate variability than Abies spectabilis. Moreover, Rhododendron campanulatum showed a positive response to winter temperatures (December-February). Abies spectabilis appears to be more vulnerable to the currently changing climatic conditions, indicating shifting competitive relationships of Himalayan treeline species that need to be considered to understand and predict the effects of climate change on treeline dynamics.
In northeastern Canada, lakeshore trees are of particular interest because they eventually become lake subfossils, which serve as main archives of past climate fluctuations over the last millennium. However, the extent to which these lakeshore trees, growing at the aquatic-terrestrial interface, carry stable isotopic series representative of regional mesic forests remains unclear. The main objective of this study is to determine whether carbon (C) and oxygen (O) stable isotopes (δ13C and δ18O) and ring width indexes (RWI) series from black spruce trees [Picea mariana, (Mill.) BSP.] growing along boreal lakeshores exhibit similar variations to those from trees growing farther away from the shores (upland trees). To verify this similarity, we compared inter-annual δ13C and δ18O variations from both environments, in boreal Quebec (eastern Canada), over the 1940–2015 period. Chronologies of intracellular CO2 concentration (ci) and intrinsic water use efficiency (iWUE) were derived from the δ13C series. Our results suggest that fractionation of C and O isotopes, in both sites, is affected jointly by rising maximum temperatures (Tmax) and Vapor Pressure Deficit (VPD) during summer, controlling gas exchanges at the leaf level. By contrast to average δ18O whose average values remained stationary through time, the δ13C records presented evident changes in acclimation strategies to rising CO2, with an early phase of strong stomatal regulation followed by a more moderate response after about 1975. Overall, the conformity of isotopic series suggests that black spruce, regardless of topographic position, can act as a reliable recorder of regional scale, past temperatures, atmospheric dryness and ecophysiological adaptation of boreal forest to climate variability.
Better knowledge of how thinning affects the radial growth of drought-prone plantations is needed to improve their management. This is the case of Tunisian stone pine (Pinus pinea) plantations, which are subjected to aridification and have been planted in sites with very different site conditions, from coastal dune ecosystems to mountain locations. To assess how thinning influenced radial growth of stone pine plantations, eight sites were sampled in Tunisia, considering heavily (two sites) and moderately (two sites) thinned stands, and also unthinned stands (four sites). We used tree-ring methods to quantify radial growth values, expressed as basal area increment (BAI) and trends, and to evaluate how year-to-year radial growth variability responded to climate variability, particularly drought stress. Stone pine radial growth decreased in response to warm dry conditions from the prior autumn to the current spring, with 9-month-long droughts peaking in early summer greatly constraining growth. However, the radial growth rates, as well as the responses to climate, greatly varied between sites, regardless of thinning treatment. Mean BAI values were higher in thinned than in unthinned stands, and the post-thinning BAI increase lasted longer, from 1 to 4 years, as thinning intensity increased. Thinning enhanced the growth of thinned stands as compared to unthinned stands during dry periods, but not during wet periods. Recently thinned and unthinned stands showed similar growth sensitivity to drought, which depended on site climate and soil conditions. Thinning improved the radial growth of stone pine plantations, but its impacts on the stands depended on thinning intensity, site conditions, and post-thinning drought severity. Therefore, thinning treatments should be tailored to site conditions and take advantage of wet periods to maximize benefits in terms of wood production.
The Arctic is warming nearly four times faster than the global average, with Svalbard among the regions experiencing the most extreme warming. This has likely driven widespread "greening" of the archipelago, yet in-situ data on tundra productivity in Svalbard remain scarce, and satellite-based measurements are challenged by cloud cover and low sun angles. This study assessed whether Salix polaris growth ring width can serve as a proxy for large-scale tundra productivity on Svalbard, quantified using NDVI. The results indicate that S. polaris growth rings are not a reliable indicator, as only two of nine sites returned a significant (p < 0.05) ring width-NDVI relationship, associations across sites were very weak (R-2 < 0.05), and predictive performance of ring-width timeseries for local interannual tundra NDVI based on unseen sites was very poor (Nash-Sutcliffe Efficiency < -2). These findings contrast with studies on other Salix species and small-scale biomass changes. S. polaris radial growth increased with summer temperature and thawing degree-days but decreased with freezing degree-days and delayed snowmelt at multiple sites, while other climatic effects were site-specific. NDVI responded more consistently to climate, increasing with summer temperature, thawing degree-days, and summer precipitation, and decreasing with delayed snowmelt and winter precipitation. Differences in how S. polaris radial growth and NDVI respond to climate, along with the influence of abundant non-vascular vegetation on NDVI, likely explain why S. polaris growth rings are mostly unsuitable as a proxy for large-scale tundra productivity in this High Arctic tundra region, as approximated by satellite-derived NDVI.
Annual shrub-growth measurements provide valuable information on the climate response of the dominant woody growth forms of Artic and alpine ecosystems. Yet, such measurements are time consuming and challenging due to the complex wood anatomy and often poorly distinguishable ring-boundaries. Here, machine-learning based algorithms may help to overcome these constraints. Iterative Next Boundary Detection, or INBD, refers to a method that employs machine learning to identify and segment ring boundaries within shrub cross-sections. We developed an INBD framework and tested it on two widespread arctic-alpine shrub species, i.e. Dryas octopetala and Empetrum hermaphroditum. We validated the method comparing manually measured shrub-ring width series with the corresponding series determined by INBD. The performance evaluation revealed INBD to operate fairly well for both species and, in particular, for E. hermaphroditum. The commonly used metrics to assess the cross-dating of shrub-ring width series, mean inter-series correlation and Gleichla & uml;ufigkeit, indicated that INBD outperformed manual measurements. Moreover, INBD analyzed the images 5.5 times faster in comparison to manual measurements and additionally provided outputs such as ring area measurements. Our analyses show that INBD largely improves the accuracy and speed of cross-dating arctic-alpine shrubs, although its performance remains sensitive to image quality and species-specific wood anatomical features, highlighting the need for large and diverse training datasets. Consequently, we advocate for the adoption and further development of the INBD method in dendroecological research, as it substantially improves shrub ring measuring techniques and the study of shrub-related ecological dynamics.
The Ottoman Yemis & cedil; Hall in Istanbul, a major 19th-century fresh fruit and vegetable market, provides a unique case study for investigating historical construction practices, timber use, and long-distance trade networks. This study combines xylological and dendrochronological analyses to identify the wood species used and to date the construction. Six wood species were identified: Quercus L. sect. Quercus (oak), Fagus orientalis Lipsky (Oriental beech), Castanea sativa L. (chestnut), Abies nordmanniana (Steven) Spach (Black Sea fir), Picea A.Dietr. (spruce), and Pinus nigra Arnold. (black pine). Dendrochronological results indicate that most timbers were employed in the second half of the 19th century, with oak and fir around the 1880s and spruce around 1893-1894. Provenance analysis shows that oak, fir, pine, and beech originated from the western Black Sea, and notably, spruce from Ukraine, suggesting imports from the Russian Empire. These findings reveal shifts in timber trade routes due to socio-political changes and highlight the continuity and adaptability of timber use in late Ottoman Istanbul. The study provides valuable data for the history of Ottoman construction and offers guidance for historically accurate restoration.
