Tree-ring based reconstructions of climate in pre-instrumental times render a cornerstone of earth-system science and critically rely on statistical relationships between meteorological observations and natural proxy archives. Recent studies have frequently reported that these relationships are not stable in time (non-stationarity), possibly caused by global change (climate, atmospheric CO₂), data resolution and quality, and statistical methods applied. Here, we assess the elusive impacts of these factors on the palaeoclimatological potential across the Northern Hemisphere. Scrutinizing spatiotemporal patterns in widely applied validation metrics derived from 3,781 tree-ring chronologies and 517 published dendroclimatic studies, we show that temperature and precipitation sensitivity have increased in the late 20^th century. This increase was consistent with trends derived from our meta-analysis. Projecting our results into climate scenarios for the 2021-2040 period indicated further expansion of areas with strong water limitation (+5±2%), whereas the areas with strong temperature limitation were projected to shrink by 8±3% (tree-ring width proxy) and 3±2% (maximum latewood density proxy). Moreover, under increased atmospheric CO₂ concentrations and consequently water-use efficiency, water limitation on tree growth may weaken and so the sensitivity to precipitation with consequences for corresponding reconstructions. These spatiotemporal shifts in the climate response of tree growth indicate that continued climate change over the next decades will substantially alter our capacity to establish a robust historical baseline for climate change research. However, our assessment of 517 published climate reconstructions revealed that scientists have, so far, successfully conserved climate signals in trees through refined statistical approaches. But we deem it unlikely that methodological advances will continue to compensate for projected weakening temperature correlations, which will pose a daunting challenge for future temperature reconstructions based on TRW records. Encouragingly, despite minor decreases in projected climate sensitivity, MXD is expected to remain a strong temperature proxy. High-resolution paleoclimatology will thus need new innovations to ensure its continued support of earth system science. Lastly, a better understanding of tree growth response to environmental changes is crucial for accurately addressing non-stationarity in climate reconstructions.

Jevšenak, J., Buras, A., Babst, F., 2024. Shifting potential for high-resolution climate reconstructions under global warming. Quaternary Science Reviews 325, 108486.

How to cite: Jevšenak, J., Buras, A., and Babst, F.: Shifting potential for high-resolution climate reconstructions under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6784, https://doi.org/10.5194/egusphere-egu24-6784, 2024.

Throughout history, humans have relied on wood for constructions, tool production or as an energy source. How and to what extent these human activities have impacted plant abundance and composition over a long-term perspective is, however, not well known. To address this knowledge gap, we combined 44 239 precisely dated tree-ring samples from economically and ecologically important tree species (spruce, fir, pine, oak) from historical buildings, and pollen-based plant cover estimates using the REVEALS model from 169 records for a total of 34 1° x 1° grid cells for Central Europe. Building activity and REVEALS estimates were compared for the entire study region (4–15° E, 46–51°N), and for low (< 500m asl) and mid/ high elevations (≥ 500m asl) in 100-year time windows over the 1150–1850 period. Spruce and oak were more widely used in wooden constructions, amounting to 35% and 32%, respectively, compared to pine and fir. Besides wood properties and species abundance, tree diameters of harvested individuals, being similar for all four species, were found to be the most crucial criterion for timber selection throughout the last millennium. Regarding land use changes, from the 1150-1250’s onwards, the forest cover generally decreased due to deforestation until 1850, especially at lower elevations, resulting in a more heterogeneous landscape. The period 1650‒1750 marks a distinct change in the environmental history of Central Europe; increasing agriculture and intense forest management practices were introduced to meet the high demands of an increasing population and intensifying industrialization, causing a decrease in plant/palynological diversity, in particular at low elevations. Likely the present Central European landscapes originated from that period. Our results further show that land use has impacted vegetation composition and diversity at an increasing speed leading to a general homogenization of landscapes through time, highlighting the limited environmental benefits of even-aged plantation forestry.

How to cite: Seim, A., Antoine, E., and Marquer, L. and the dendro-pollen team: Legacy of last millennium timber use on plant cover in Central Europe: insights from tree rings and pollen, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8585, https://doi.org/10.5194/egusphere-egu24-8585, 2024.

In this study, we used the Suceava oak tree-ring width chronology to reconstruct the paleo hydroclimatic events in eastern Europe, a region for which high-resolution paleoclimatic evidence is broadly missing. Our regional oak chronology reflects July hydroclimate variability in the form of the twelve months Standardized Precipitation Index over large parts of Romania, Ukraine, and the Republic of Moldova, for which high-resolution paleoclimatic evidence is broadly missing. Most of the reconstructed hydroclimatic extremes back to 1216 CE are confirmed by documentary evidence, and a robust association is found with large-scale atmospheric circulation patterns in the Northern Hemisphere and sea surface temperatures over the North Atlantic. Reconstructed pluvials coincide with a high-pressure system over the North Atlantic Ocean and north-western Europe, and with a low-pressure system over south-western, central, and eastern Europe, whereas historical droughts coincide with a high-pressure system over Europe and a low-pressure system over the central part of the Atlantic Ocean.

How to cite: Roibu, C.-C., Ionita, M., Mursa, A., Crivellaro, A., Wazny, T., Nagavciuc, V., Cotos, M.-G., Stirbu, M.-I., Asandei, M.-E., and Andriescu, C.-M.: 804 years drought reconstruction based on oak tree rings for Eastern Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16567, https://doi.org/10.5194/egusphere-egu24-16567, 2024.

With the onset of anthropogenic climate change, the ClimateCultures project aims to tackle the question “What happened the last time we encountered rapid climate change?” using evidence from tree rings and historical records to paint a picture of the natural impacts and societal responses in Norway during the Little Ice Age. More specifically, we aim to investigate short-lived extreme cold events in the 1700’s. This calls for a more regional scale to account for complex climate drivers over a mountainous country with regional climatic differences and local communities’ responses. Here we present a case study of Scots pine wood collected in western Norway, a region known for mild temperatures and high precipitation (relative to average Norwegian climate), and compare various tree ring proxies including ring width, Blue Intensity and stable oxygen isotopes. While this record does not extend to the 1700’s, we can consider the merits and limitations of each proxy when compared to the instrumental records. This study will provide a basis for climate reconstructions, particularly focusing on hydroclimate signals in Norwegian chronologies. 

How to cite: Khumalo, W. H., Svarva, H. L., Nadeau, M.-J., Seiler, M., Philippsen, B., Kallevik, M., and Collet, D.: A multiproxy comparison of Scots pine wood in western Norway , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17143, https://doi.org/10.5194/egusphere-egu24-17143, 2024.

Silver fir (Abies alba) is a key forest tree species in Central Europe growing most commonly in its mixtures with Fagus sylvatica and Picea abies. It is also an important species to dendrochronology due to its longevity, historic timber utilization, and generally well-synchronized interannual growth series. However, a growing number of dendroecological studies focusing on climate change has left the species relatively underrepresented even compared to its lower abundance as a dominant forest tree species. It is also due to its weaker growth–climate relationship, compared to species growing in more climatically limited (first of all water-limited) environments. In forest sciences, the species has received wide attention during the complex forest decline phase after the late 1970s and during the 1980s, referred to as the “Waldsterben” in the German-speaking countries of Central Europe, highlighting the negative effects of air pollution of that time, particularly in the context of silver fir. In the era of climate change, the species is gaining renewed interest, especially for its further admixing potential to climatically more resilient forest stands.

In our study, we have investigated the long-term trends and the interannual climatic signal in the radial growth chronologies from monospecific stands of silver fir at seven sites representing a broad climatic and elevational gradient along the distribution of the species. The measured chronologies reveal an increasing low-frequency growth synchrony, starting with a periodic growth increase at the investigated sites since the 1980s, regardless of tree and stand age. Preliminary correlation results suggest that the water-balance related climatic signal has been introduced or has significantly increased between the periods 1961–1990 and 1991–2020. This has been partly associated with a shift or even clear change of sign in the temperature signal. Significant relationships, yet with varying sign, have been also found with the atmospheric water vapor content at each site.

The main research questions aim to focus on the pace and term of this change manifested in the climatic signal, namely (i) whether the growing conditions have changed over longer term or were rather influenced by specific years, (ii) if the change was abrupt or more gradual over time. To answer these questions, different climate data-driven models are fitted to the (detrended) growth series, and the error of the model fit is assessed by shorter windows. The temporal patterns of the change, together with the general growth trends identified, are compared to the climatic trends and the frequency of drier periods since the 1980s, with attention to the timescale of the “Waldsterben” phenomena. The interpretation of the results shall reflect a complex interplay of different drivers of forest conditions during the last decades of the 20th century and the inherent uncertainties thereof. Nevertheless, it can contribute to the dendroecological knowledge of an ecologically and silviculturally important species at the crossroads of past legacies, current and predicted challenges.

How to cite: Garamszegi, B., Grabner, M., Wächter, E., Gadermaier, J., and Katzensteiner, K.: Converging trends and strengthening climatic signal in the radial growth of Abies alba in Austria – between the legacies of “Waldsterben” and the era of climate change?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20227, https://doi.org/10.5194/egusphere-egu24-20227, 2024.

Tree-ring oxygen isotope (δ¹⁸O_TR) is a powerful proxy for paleoclimatology, ecology and archaeology, δ¹⁸O_TR studies in Asia over the past ~50 years have made signiffcant achievements in improving our understanding of Asian climatic and ecological systems. Here, we review these developments in δ¹⁸O_TR research in Asia. Most study sites are located within East Asia, Southeast Asia, South Asia, and North Asia, and δ¹⁸O_TR records from conifers, broadleaf trees, and shrubs have been produced. Progress has been made in the following areas: (1) Experimental techniques. The novel plate method for cellulose extraction has been developed, which reduces experimental time and greatly improves efffciency. (2) Development of δ¹⁸O_TR chronologies. Ninety-six chronologies exceeding 200 years in length have been produced. A 4354-year δ¹⁸O_TR chronology with an annualresolution has been produced in Japan, and a 6700-year δ¹⁸O_TR chronology with a 1–5 year resolution has been produced in the northeastern Tibetan Plateau, which is the longest in Asia. (3) Biological inffuences on δ¹⁸O_TR. Variations of intra- and inter-tree and inter-species δ¹⁸O_TR have been investigated, and the relationship between tree age and δ¹⁸O_TR has been explored. (4) Climatic implications. Seasonal δ¹⁸O_TR records primarily reffect the variability of precipitation δ¹⁸O, facilitating high-resolution paleoclimate reconstructions, while interannual δ¹⁸O_TR records mainly reffect summer moisture variability. (5) Climate reconstructions. Quantitative estimates have been produced for past precipitation, relative humidity, PDSI (Palmer Drought Severity Index), runoff, and other parameters from δ¹⁸O_TR records. Since 1850, δ¹⁸O_TR chronologies in monsoon regions show upward trends indicative of drying, while these from westerlies regions exhibit downward shifts implying wetting. (6) Dating. Intra- and inter-annual δ¹⁸O_TR records help determine the annual growth of trees without rings and facilitate the cross-dating of trees with rings. Thus, the dating of archaeological and buried wood is feasible via comparisons with δ¹⁸O_TR master chronologies. Promising areas of development include climatic implications (e.g., Position-speciffc isotope analysis, seasonal δ¹⁸O_TR records on longer timescales and larger spatial scales), climate reconstructions (syntheses of multiple sites and records, development of long chronologies, deep time paleoclimate reconstructions) and ecological applications (e.g., the response of trees to climatic extremes, and the combinations with multiple tree-ring multiple proxies such as width and density). 

How to cite: Xu, C., Huang, R., An, W., Zhao, Q., Zhao, Y., Ren, J., Liu, Y., and Guo, Z.: Tree ring oxygen isotope in Asia , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4297, https://doi.org/10.5194/egusphere-egu24-4297, 2024.

Climate change is strongly influencing global shifts in forest ecosystem dynamics. There has been a twofold increase in canopy mortality within the temperate forests of Europe in the past thirty years. The trend has been further intensified by recent drought episodes occurring between 2018 and 2020, leading to increased instances of die-offs and reduced vitality among key tree species.

In central Europe, notably in Germany, European beech (Fagus sylvatica L.) stands out as a tree species with high ecological and economic significance. Recent severe drought conditions led to substantial vitality loss and mortality. Nevertheless, there was considerable diversity in how individual beech trees responded to drought, with some trees in the same location being heavily impacted while others remained seemingly unaffected. Factors influencing this uneven response are still not fully understood.

In this study, we gathered 600 beech tree-ring width series from 13 sites located across Northern Bavaria, along a climatic gradient. We explore the differences in growth between two groups of trees (damaged/vital) using a dendroecological approach. We evaluated loss of vitality through the implementation of mortality and critical slowdown indicators such as long-term growth decline or changes in climate memory, as well as climate/growth relations and growth synchrony indicative of changing growth limitations.

While we did not find significant differences between groups in terms of climate memory and drought sensitivity, our results showed a divergence in the growth patterns of vital and damaged trees following repetitive exposure to drought events. We detected higher growth rates of damaged trees prior to the last three decades, after which their growth rates declined stronger than vital trees. Our results suggest that faster-growing beech trees may be more susceptible to drought-induced mortality, which is in line with findings of higher vulnerability of faster-growing trees to environmental stressors.

How to cite: Žmegač, A. and Zang, C. S.: Predisposition of European beech to drought-induced die-off along a climate gradient in Northern Bavaria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17581, https://doi.org/10.5194/egusphere-egu24-17581, 2024.

The prospect for European beech forests (Fagus sylvatica L.) over the course of the 21^st century is uncertain due to climate change. In context, climate sensitivity of growth is a valuable indicator of physiological integrity, but its natural variability is poorly understood in productive, closed canopy forests. Climate sensitivity may not only depend on temporal and spatial differences in climatic conditions, but also on trees’ rank progression in the course of forest maturation.

Here, we determine how the drought sensitivity of secondary growth in beech varies in space and time according to growth trends, growth variability and climatic conditions. The temporal variability of these variables is determined via a moving window approach using a network of tree-ring sites across the species’ geographical and climatological distribution. The moving window derived variables are applied to a linear mixed-effects model allowing for the estimation of linear, non-linear and interactive effects. Furthermore, dry and wet subsets of the data are supplied individually to determine differences between dry and wet site conditions.

Our results indicate considerable variability in climate sensitivity due to complex non-linear and interactive effects of all variables. Generally, drought sensitivity is strongly and positively coupled with growth variability and climatic aridity. The strong non-linear and interactive effects between all variables result in drought sensitivity changing considerably with changes in growth variability and growth trends when climatic conditions are average or wetter than average. However, during dry time-periods, drought sensitivity is consistently high and decoupled from changes in growth trends and growth variability. While these patterns remain relatively similar between dry and wet sites, dry sites show significantly higher drought sensitivity compared to wet sites overall.

In conclusion, we found beech’s drought sensitivity to be significantly affected by growth variability, growth trends and climatic conditions. Furthermore, the influence of each variable on drought sensitivity changes drastically as they interact, indicating all these factors need to be considered when interpreting beech’s climate sensitivity.

How to cite: Leifsson, C., Buras, A., Rammig, A., and Zang, C. and the Beech Network: Determining influencing factors of climate-growth relationships of European beech across its ecological amplitude, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20751, https://doi.org/10.5194/egusphere-egu24-20751, 2024.

Boreal forests play an important role in the global carbon cycle (C), and there is increasing interest in understanding how they react to environmental changes, including nitrogen (N) and water limitations, which may influence future forest growth and C storage. Utilizing tree cores archived by the Swedish National Forest Inventory, we measured stemwood traits, including stable N and C isotope composition, which provides information on N availability and water stress, respectively, as well as N and C content, and the C/N ratio over the period 1950–2017 in two central Swedish counties, Jämtland and Västernorrland, covering an area of ca. 55,000 sq. km (n = 1038). We tested the hypothesis that wood traits change over time and that temporal patterns would vary depending on alternative dendrochronological reconstruction methods, i.e. the established standard “single tree method” (STM) or a conceptually stronger “multiple tree method” (MTM). Averaged across all MTMs, our data showed that all five wood traits for Picea abies and Pinus sylvestris changed over time. Wood δ¹⁵N declined strongly, indicating progressive nitrogen limitation. The decline in δ¹³C followed the known atmospheric δ¹³CO₂ signal, indicating there was no change in water stress. In addition, wood N increased significantly, while C and C/N ratios declined over time. Furthermore, wood trait patterns sometimes differed between dendrochronological methods. The most prominent difference was for δ¹⁵N, where the slope was much shallower for the STM compared to MTMs for both species, indicating that mobiity of contemporary N is problematic when the STM is used, leading to much less sensitivity to detect historical signals. Our study shows strong temporal changes in boreal wood traits and also indicates that the field of dendroecology should adopt new methods and archival protocols for studying highly mobile element cycles, such as nitrogen, which are critical for understanding environmental change in high latitude ecosystems.

How to cite: Bassett, K. R., Östlund, L., Gundale, M. J., Fridman, J., and Jämtgård, S.: Forest inventory tree core archive reveals changes in boreal wood traits over seven decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16465, https://doi.org/10.5194/egusphere-egu24-16465, 2024.

The impact of air pollution on forests, especially in urban areas, has been an increasingly discussed topic in recent years. A number of pollutants, including heavy metals, are released into the atmosphere from various sources, such as mining activities, non-ferrous metal processing plants, fossil fuel combustion, and can have adverse effects on tree growth but also on vigor of other species including humans.

We compared the concentrations of several elements in tree-ring wood from two conifer species (Silver fir-Abies alba, and Norway spruce-Picea abies) growing in polluted and unpolluted areas. Two regions (Bicaz and Tarnița) subjected to historical changes in pollution and located in northern Romania were selected. Two methods of chemical analyses were used: inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometry (XRF).

Silver fir trees from the intensively polluted area in Tarnița region are negatively impacted by industrial pollution according to their Mn concentrations in wood which are, on average, three times higher than in the unpolluted areas (ca. 30 vs. 10 mg·kg^-1). This finding is consistent with both ICP-MS and XRF analyses, but this difference was found in Norway spruce only in XRF data which detected 7 times higher Mn concentrations in trees from polluted areas than in those from unpolluted areas (ca. 700 vs. 100 mg·kg^-1).

In the Tarnița region, Norway spruce was able to accumulate a higher quantity of heavy metals compared to Silver fir, but the most pronounced differences between polluted and unpolluted were found in Silver fir.

The two analysis methods complemented each other with ICP-MS being a qualitative method with a low detection limit of some elements, and XRF being a more quantitative method with high detection limit and satisfactory accuracy.

How to cite: Cuciurean, C., Sidor, C. G., Camarero, J. J., Buculei, A., and Badea, O.: Detecting changes in industrial pollution through the analyses of heavy metals concentrations in tree-ring wood from Romanian conifer forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15959, https://doi.org/10.5194/egusphere-egu24-15959, 2024.

The effects of rising atmospheric CO₂ concentrations (C_a) with climate warming on intrinsic water-use efficiency (iWUE) and radial growth in boreal forests are still poorly understood. We measured tree-ring cellulose δ¹³C,δ¹⁸O, and tree-ring width in Larix dahurica (larch) and Betula platyphylla (white birch), and analyzed their relationships with climate variables in a boreal permafrost region of northeast China over past 70 years covering a pre-warming period (1951-1979; base period) and a rapid-warming period (1980-2018; warming period). We found that white birch but not larch significantly increased their radial growth over the warming period. The increased iWUE in both species was mainly driven by elevated C_a but not climate. White birch but not larch showed significant positive correlations between tree-ring δ¹³C,δ¹⁸O and summer maximum temperature as well as vapor pressure deficit in the warming period, suggesting a strong stomatal response in the deciduous birch but not in the conifer larch to climate warming. The climate-warming induced radial growth enhancement in white birch is associated with a more ‘conservative’ (low g_s, constant A) water use strategy than in larch (constant g_s, high A), suggesting an advantage for the former than the latter in a warming world in the permafrost regions.

How to cite: Qi, X., Treydte, K., Saurer, M., Fang, K., Ann, W., Lehmann, M., Liu, K., Wu, Z., He, H., Du, H., and Li, M.-H.: Contrasting water use strategies to climate warming in white birch and larch in a boreal permafrost region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20980, https://doi.org/10.5194/egusphere-egu24-20980, 2024.

Under warmer and drier climate scenarios, the growth and resilience of forests will be critically affected by more frequent and severe droughts. Since the 1970s, China has launched several afforestation programs aimed at regional ecological protection, playing an important role for reaching carbon neutrality by 2060.

This study provided a detailed analysis of the growth suitability of the main planted conifers (Pinus sylvestris var. mongolica, Pinus tabulaeformis) and broadleaves (Populus spp., Robina pseudoacacia) in the semi-arid northern China. We compared the radial growth trends of plantations and their responses to extreme droughts from 1980 to 2018.

Growth of most plantations has significantly increased, but broadleaves showed recent growth reductions in the past decade, which may be related to tree age and reduced soil water content. Nevertheless, under warmer climate scenarios, growth of plantations is forecasted to continue increasing. Broadleaves showed a better post-drought recovery, probably linked to their anisohydric behavior, than conifers, which presented a better resistance to drought. Growth of conifers depended more on warmer temperature and better precipitation conditions during the growing season, whereas broadleaves mainly reacted to warm temperature. Additionally, pre-drought growth levels weakened resilience components, while post-drought precipitation compensated drought-induced growth deficit. Growth and resilience were negatively related to tree age, whilst higher stand density reduced growth. This assessment and projections of growth and drought resilience indicate the sustainability of most plantations in semi-arid regions, but future warmer and drier conditions may lead to an uncertain future regarding forest health and reduce their carbon sink potential.

Keywords: Growth trends; Drought resilience; Tree-ring analysis; Plantations; Three-North Shelter Forests Program.

How to cite: Li, J., Xie, Y., Julio Camarero, J., Gazol, A., González de Andrés, E., Ying, L., and Shen, Z.: Growth and drought resilience of planted conifers and broadleaves in the semi-arid Northern China., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5939, https://doi.org/10.5194/egusphere-egu24-5939, 2024.

Carbon isotope composition of tree‐ring (δ¹³C_Ring) is a commonly used proxy for environmental change and ecophysiology. δ¹³C_Ring reconstructions are based on a solid knowledge of isotope fractionations during formation of primary photosynthates (δ¹³C_P), such as sucrose. However, δ¹³C_Ring is not merely a record of δ¹³C_P. Isotope fractionation processes, which are not yet fully understood, modify δ¹³C_P during sucrose transport. We traced, how the environmental intra‐seasonal δ¹³C_P signal changes from leaves to phloem, tree‐ring and roots, for 7 year old Pinus sylvestris, using δ¹³C analysis of
individual carbohydrates, δ¹³C_Ring laser ablation, leaf gas exchange and enzyme activity measurements. The intra‐seasonal δ¹³C_P dynamics was clearly reflected by δ¹³C_Ring, suggesting negligible impact of reserve use on δ¹³C_Ring. However, δ¹³C_P became increasingly ¹³C‐enriched during down‐stem transport, probably due to post‐photosynthetic fractionations such as sink organ catabolism. In contrast, δ13C of water‐soluble carbohydrates, analysed for the same extracts, did not reflect the same isotope dynamics and fractionations as δ¹³C_P, but recorded intra‐seasonal δ¹³C_P variability. The impact of environmental signals on δ¹³C_Ring, and the 0.5 and 1.7‰ depletion in photosynthates compared ring organic matter and tree‐ring cellulose, respectively, are useful pieces of information for studies exploiting δ¹³C_Ring.

How to cite: Rinne-Garmston, K., Tang, Y., Sahlstedt, E., Adamczyk, B., Saurer, M., Salmon, Y., del Rosario Domínguez Carrasco, M., Hölttä, T., Lehmann, M., Mo, L., and Young, G.: Drivers of intra‐seasonal δ13C signal in tree‐rings of Pinus sylvestris as indicated by compound‐specific and laser ablation isotope analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8957, https://doi.org/10.5194/egusphere-egu24-8957, 2024.

Trees encapsulate environmental changes in their growth through the records in the tree rings, but extracting this signal proves challenging and time consuming. These challenges persist in the study of geomorphic processes, requiring meticulous and prolonged efforts by a specialised technician to identify and date growth disturbances (GD). The presence of false annual rings adds another layer of complexity to the task. 

Today, many classical computer vision-based techniques have been developed for the automatic detection of annual rings. However, to the best of our knowledge, these techniques have not been applied to the detection of GD associated with geomorphic events, which are more challenging because they do not present as clear visual patterns as annual rings. Deep learning-based architectures have shown great capacity for automatic localisation of objects in images with complex shapes.

We have applied these systems to the segmentation of evidence of geomorphological processes (i) wounds (ii) callus tissue (iii) latewood (iv) traumatic resin ducts and (v) growth rings. The deep learning (DL) architectures used were Faster R-CNN with ResNet-101-FPN backbone, YOLOv8 and a U-Net architecture. For the application of the system, it is necessary divide the image into smaller patches, and post-processing techniques for the correct unification of the predictions of each image. Training and evaluation of the networks was performed in Google Colaboratory. The algorithm was tested on 150 cores taken ad hoc from a debris flow cone in the Pyrenees (Pineta Valley), where historical debris flows have occurred. The cores were subjected to a sanding process and the images were obtained using a Canon Eos8 camera. 120 were used to train and validate and 30 to test the architectures, comparing the results obtained by a classical approach and by DL. The evaluations were performed at the pixel level using the accuracy, precision and recall metrics. After post-processing the predictions, the pixels were converted into instances and the predictions were compared with the ground truth, and the metrics Intersection over Union (IoU), precision and recall per category were calculated.

Our preliminary results suggest that, with a sufficiently large dataset, deep learning-based models can capture sufficient information to identify the complex patterns to be classified. This implies that it is possible to achieve a model capable of automatically identifying geomorphological event signals, thereby speeding up the process of obtaining evidence. This opens the possibility of having proposals of event signals without subjective bias, obtaining in different studies, evidence datasets made with a homogeneous and systematised criterion.

How to cite: Zambrano Suárez, J. D., Pérez Martín, J., Muñoz Torrero Machado, A., and Ballesteros-Cánovas, J. A.: Deep Learning-Based semantic segmentation for geomorphic processes signals in tree-ring records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9146, https://doi.org/10.5194/egusphere-egu24-9146, 2024.

Dendrochemistry has been developed as a new environmental indicator in recent decades. Elements, such as Hg, Pb, and Cd, in tree rings were considered as new tracers for industrialization, air pollution, and soil contamination. However, the movement and diffusion of elements across the rings, called radial translocation, intensifies when the sapwood transforms into heartwood, which blurs the elemental records. Detecting the translocation of elements and their mobility in tree rings due to heartwood formation is crucial for the availability and confidence of applying dendrochemistry. We developed methods to evaluate radial translocation. 1. The iTrax core scanner was used to scan tree ring core slices of four conifers in Taiwan to evaluate the feasibility of applying the iTrax core scanner to analyze the elemental trends in tree ring cores and the scanning parameters. 2. The elemental distributions in tree ring cores of different species were measured. 3. The mobilities of elements were evaluated. Forty-second exposure was successful and reproducibly scanned K, Ca, V, Cr, Mn, Fe, Cu, Sr, and Pb contents. Results show that the levels of Ca and K in the tree ring of all four species and the levels of Mn of three species significantly differ between the heartwood and sapwood phases. For the remaining elements, including V, Cr, Fe, Cu, Sr, and Pb, there is no significant difference between phases. After treating with an extraction solution to remove soluble or mobile elements, the different levels of Ca, K, and Mn between phases were not observed, indicating the mobility of these elements. The effect of radial translocation should be considered when applying the three elements as environmental tracers.

How to cite: Wei, H.-L., Shen, C.-C., Löwemark, L., Liao, C.-Y., Chen, S.-L., and Hsieh, C.-K.: Rapid detection of elements' radial translocation and mobility in tree rings by iTrax core scanner, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14763, https://doi.org/10.5194/egusphere-egu24-14763, 2024.

Illegal logging and its related timber trade is one of the major drivers of forest loss, species diversity and economic and social conflicts. Over the last decades, several international and national regulations have been implemented as an attempt to flight this practice. At the same time, different scientific approaches such as genetics, mass spectrometry, and wood anatomy show great potential for timber identification. Our objective was to assess the potential of Near Infrared Spectrometry (NIRS), chemical elements and stable isotopes as tools to increase accuracy of site of origin identification for Cedrela fissilis. Between 3 to 4 tree cores were collected at breast height from Cedrela trees from three sites in Southeastern Bolivia. For the isotopic analysis, annual tree rings were identified and dated. Cellulose extraction was extracted from the cores following the standard methodology of Jayme-Wise. Wood flakes without previous treatment were complementarily analyzed using a MATRIX-F spectrometer (Bruker Optics) for the NIR measurement and a Niton XL3t XRF Analyzer for the elemental analyses. We then used Principal Component Analyses (PCA) and Random Forest to assess the potential of these methods to discriminate among sampling sites. Random Forest on elemental raw data had a site discrimination accuracy about 84%, with strontium (Sr), copper (Cu) and Cadmium (Cd) as potential tracers. For NIRS spectra, PC1 explained 99% of the variance with mean site discrimination accuracy about 78%. Preliminary results of stable oxygen (δ¹⁸O) and carbon (δ¹³C) isotopes showed distinct patterns across the sites but accuracy is still under evaluation through the analyses of annual measurements. Although discrimination accuracies were similar among timber identification methods, each method has the potential to identify a different site. Our preliminary results suggest that site discrimination performance may be specific to each method and site.

How to cite: Paredes Villanueva, K., Kagawa, A., Abe, H., Kojima, M., Zhang, C., Ohashi, S., Akita, A., Takahashi, K., Uriarte, M., and Andreu-Hayles, L.: Novel provenance approaches for tracing Cedrela timber in Bolivia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22320, https://doi.org/10.5194/egusphere-egu24-22320, 2024.