C04_P01

δ¹³C and intrinsic water use efficiency (iWUE) for trees in various health conditions – case study for Świerklaniec Forest District

Benisiewicz B¹,  Pawełczyk S², Kłusek M³

¹Silesian University Of Technology, Gliwice, Poland, ²Silesian University Of Technology, Gliwice, Poland, ³Silesian University Of Technology, Gliwice, Poland

The research was carried out for two pines growing side by side in the Świerklaniec Forest District. One tree was in good health condition, the other pine had damaged crown and was destined to be cut down. Tree cores were subjected to dendrochronological analysis. Based on these studies, cores were divided into annual increments and subjected to chemical preparation. Carbon isotopic composition of α-cellulose samples was determined using mass spectrometer coupled to the elemental analyzer. Additionally, based on the δ¹³C  values, the iWUE values were calculated, and trees sensitivity to change of  temperature and sum of precipitation was checked.  Isotopic studies covered the years 1967-2020.

              Until the end of the 1990s, the record of  δ¹³C had significantly lower values for a healthy tree than for a damaged tree. The isotope record of a healthy tree since 1980 is characterized by a horizontal trend, in the case of a damaged tree there is a clear downward trend from 1985 to 2000. Correlation coefficients between isotopic and climatic data indicate different sensitivity of trees to climatic factors. Apart from climatic factors, pollutant emissions could have had an impact on tree growth and δ¹³C values, especially since there is a zinc smelter near the sampling site. The characteristics of the trend can be justified by the number of pollutants emitted by industrial plants (especially SO₂), which were the highest in the 1970s and 1980s, and significantly decreased in the 1990s. Differences in iWUE, calculated from data sets, representing two trees are signifficant.

C04_P02

New high RESOLUTION project ¹⁴C data from a Glacial sub-fossil pine forest in Furadouro, Portugal

Cercatillo S¹, Friedrich M², Kromer B³, Palecek D¹, Wacker L⁴, Talamo S¹

¹Department of Chemistry G. Ciamician, Alma Mater Studiorum, University of Bologna, Via Selmi 2, 40126, Bologna, Italy, ²Hohenheim Gardens, University of Hohenheim, Ottilie-Zeller-Weg 8, D-70599, Stuttgart, Germany, ³Institute of Environmental Physics, Heidelberg University, D-69120 , Heidelberg, Germany, ⁴Laboratory of Ion Beam Physics, ETH Zurich, 8093 , Zurich, Switzerland

The year 14,226 BP marks an important border in the actual radiocarbon (¹⁴C) calibration curve: the high resolution and precision characterising the first part of the curve thanks to the potential of tree-rings, systematically decrease going back in time, where only a few floating tree-ring chronologies alternate to other low-resolution records.

The lack of resolution in the dating procedure before 14,200 years BP leads to significant issues in the interpretation and untangling of tricky facts of our past.

The research for sub-fossil trees, within the RESOLUTION project, which directly recorded atmospheric carbon (¹²C, ¹³C and ¹⁴C), and the construction of new Glacial tree-ring chronologies can improve the radiocarbon dating and therefore, to resolve puzzles in the Human Evolution history.

The sub-fossil pine trees found in situ under the current coast sediments of Furadouro, Portugal, are remnants of a Glacial lagoonal forest and represent a significant example of the huge potential given by the rare findings of trees grown during the Glacial in refugia areas, where the environmental conditions and climate allowed growth of pine trees.

Here we report of a new 220-year long pine tree-ring chronology, grown during GI 5: we describe the carefully sampling, the dendrochronological analysis and cross-dating of the trees, and the high resolution, highly reliable radiocarbon age-series with tight error ranges that we have achieved by applying the most suitable cellulose extraction protocol for sub-fossil Glacial trees, and the most advanced technologies of the MICADAS system at ETH-Zurich.

C04_P03

Radiocarbon ages of annual tree rings collected in Korea (AD 900 - 2021, 81 - 168, 131 - 211)

Hong W¹, Park Y¹, Sung K¹, Park G¹, Sakamoto M², Hakozaki M², Park J¹

¹Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon, South Korea, ²National Museum of Japanese History, Sakura City, Japan

Radiocarbon ages of annual tree rings collected in Korean Peninsula were measured using KIGAM 1MV AMS. All samples were treated by alpha cellulose extraction methods at KIGAM and NMJH. Reduction process of CO₂ to graphite was done using 24-line automatic reduction system at KIGAM. The radiocarbon ages from AD 1250 to 1850 were reported in 2013 (Hong et al.1, 2013 and Hong et al.2, 2013) with dendrochronological ages. After the reports, radiocarbon ages of tree rings from AD 1093 to 1162, AD 1188 to 1249, and AD 1851 to 1950 have been measured. The calendric ages of these samples were determined by dendrochronology or oxygen isotope patters. And recently, additional tree rings from AD 81 to 168 and from AD 131 to 211 collected from an archaeological site, Gochon-ri, were measured. The calendric ages of the samples were determined by oxygen isotope dendrochronology. Modern tree rings after AD 1950 collected from a mountain called Sogri-san, which is located in the center of South Korea, were also measured up to 2021. Those ages will be reported in this presentation and compared with IntCal13 and IntCal20 curves. Chronological variation of regional offsets in the radiocarbon ages of tree rings grown in East Asia from IntCal13 and IntCal20 will be discussed.

C04_P04

A growth rate variability of Ziziphus spina christi in North-central Oman determined by a series of radiocarbon measurements

Kitagawa H¹, Miki T², Kuronuma T³, Kondo Y³

¹Institute for Space‐Earth Environmental Research, Nagoya University, Nagoya, Japan, ²The University Museum, The University of Tokyo, Tokyo, Japan, ³Research Institute for Humanity and Nature, Kyoto, Japan

Ziziphus spina christi, known as Christ's Thorn Jujube, is a thermophilic tree grown in arid and semi-arid areas. It was already in use as a medical plant in Ancient Egypt and is currently used for multipurpose such as food, fodder, fodder fuel, drink, timber, and medicine. The ecological and chemical properties of the multipurpose plant have been intensively studied, but there is a missing knowledge about the growth rate of Ziziphus spin christi that the annual ring is unclear. We conducted a series of radiocarbon measurements of a 23 cm-long core of Ziziphus spina christi collected from Wādī Tanūf, Northcentral Oman. The secular change of growth rate was estimated by a wiggle matching method incorporating dynamic time wrapping (DTW) algorism for measuring similarity between two temporal sequences: radiocarbon calibration (IntCal20) and dataset from the Ziziphus spina christi（this study). Based on the growth rate estimated, we discussed the climatic influence on the growth rate. Our result supports the hypothesis that an increase in winter temperature may be beneficial for growth and the recent widespread of Ziziphus spina christi in the eastern Mediterranean is presumably related to a gradual increase in winter temperatures.

C04_P05

Single-year ¹⁴C dating of the lake-fortress at Āraiši, Latvia

Meadows J^1,2, Zunde M³, Lēģere L⁴, Dee M⁵, Hamann C²

¹ZBSA (Centre for Baltic and Scandinavian Archaeology), Schleswig, Germany, ²Leibniz-Laboratory for AMS Dating and Stable Isotope Research, Christian-Albrechts-University Ki, Kiel, Germany, ³Institute of Latvian History, University of Latvia, Riga, Latvia, ⁴Āraiši lake-fortress archaeological park, Cēsis, Latvia, ⁵Centre for Isotope Research, University of Groningen, Groningen, Netherlands

A timber lake-fortress on a flooded island in Lake Āraiši, central Latvia, was excavated in 1965-69 and 1975-79 by the pioneering underwater archaeologist Jānis Apals, who recognised five construction phases. Dendrochronological analysis originally produced a mixed-species conifer site chronology, which was tentatively cross-matched to a reference chronology from Novgorod, Russia, indicating a felling date of c.AD 930 for timbers from the earliest phase. A more rigorous analysis produced a 95-year floating chronology for the best-preserved Norway spruce (Picea abies (L.) Karst.) timbers from the earliest phase, which was dated by ¹⁴C wiggle-matching with the IntCal13 calibration curve, suggesting a felling date of cal AD 775–784 (Meadows and Zunde 2014, Geochronometria 41(3):223-33). If this range was accurate, it should have been possible to locate the AD 775 Miyake event (Miyake et al. 2012, Nature 486(7402):240-2) in single-year cellulose samples from the final decade of the Āraiši spruce chronology. However, repeated attempts, with replication of the final decade between the Kiel and Groningen laboratories, were unsuccessful. Additional sampling in 2020-21 unambiguously located the AD 775 event 60 years before the spruce felling date, dating the first phase of construction to AD 835. The new results raise questions both about the treatment of ¹⁴C outliers in the original (2014) wiggle-match, and about the IntCal20 data set; like Philippsen et al. (2021, Nature 601(7893):392-6), we suspect that IntCal20 is too low in the 830s AD.

C04_P06

AMS radiocarbon investigation of the African baobabs from the semi-arid cloud forest of Wadi Hinna, Dhofar, Oman

Patrut A^1,2, Molnar M³, Patrut R¹, Rakosy L⁴, Brown J⁵, Varga T⁶, Ratiu I^1,2

¹Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, Cluj-Napoca, Romania, ²Babes-Bolyai University, Raluca Ripan Institute for Research in Chemistry, Cluj-Napoca, Romania, ³Interact Centre,Institute for Nuclear Research, Debrecen, Hungary, ⁴Babes-Bolyai University, Faculty of Biology and Geology, , Cluj-Napoca, Romania, ⁵Qatar University, College of Arts and Sciences, Doha, Qatar, ⁶University of Debrecen, Doctoral School of Physics, , Debrecen, Hungary

Wadi Hinna is a small semi-arid valley (3 km2) at the edge of the Dhofar Mountains (17º03' N, 54º36' E, altitude 300-360 m) and at 20 km from the coastal plain, in southern Oman. Wadi Hinna hosts a unique water-limited cloud forest of African baobabs (Adansonia digitata).

The precipitation (annual rainfall 130 mm) falls during the rainy season (mid-June to mid-September), when moist air from the Indian Ocean, i.e., the southwest monsoon, encounters the mountains, leading to clouds and dense fog. The rainfall is significantly supplemented by horizontal precipitation, namely cloud water interception within the canopy of trees.

Over 120 baobabs grow on a slope among huge stones of sedimentary rocks. We dated by AMS radiocarbon wood samples from the largest baobabs. We found that they exhibit, with one exception, ages of several hundreds of years. The exception is the Big tree of Wadi Hinna, which is by far the biggest and oldest baobab. The oldest part of the Big tree started growing more than 1000 years ago.

The African baobab typically exhibits well-defined growth rings, which correspond in many cases to one rainy season. Nevertheless, age modeling of baobab rings demonstrated that ring-growth anomalies occur more frequent than for other tree species. For the old baobabs of Wadi Hinna, we found that the ring frequency varies between 0.43 and 0.78 rings/year. The large number of missing rings is due to the semi-arid climate.

The research was funded by the Romanian Ministry of Research CNCS-UEFISCDI under grant PN-III-P4-ID-PCE-201620-2567, No. 145/2021.

C04_P07

Improved calibration method for dating multiple tree-rings and its implication on the Santorini debate

Raj H¹, Regev L¹, Boaretto E¹

¹Dangoor Research Accelerator Mass Spectromerty (D-REAMS) Laboratory, Weizmann Institute of Science, Rehovot, Israel

The Minoan eruption of Santorini, Greece, is an important and probably most debated chronological marker in contexts of the Eastern Mediterranean region. Among various age estimates of this event, one based on wiggle-matching of ¹⁴C dates from an olive branch found in Santorini by Friedrich et al. (2006) has been widely discussed. Four ¹⁴C ages were reported from this olive branch, each corresponding to a group of rings identified by X-ray tomography. Calibrated age estimates based on wiggle-matching of these ¹⁴C ages have been changing with improvements in the radiocarbon calibration curve. Such changes are important as the debate on the timing of the Minoan eruption is still not settled. It is understood that the calibration curve plays a crucial role in defining the calendar age range corresponding to ¹⁴C age(s). Interannual ¹⁴C levels can change significantly in the calibration curve, and the average ¹⁴C age of multiple rings dated together cannot always be calibrated to the middle year. Therefore, a different approach should be taken to calibrate the average ¹⁴C age of the multiple tree rings. We propose that calibration using the moving average calibration curve is more appropriate in such a case. Here, we recalibrated the four ¹⁴C  ages reported for the above olive section on the moving average calibration curves. Considering the ring counts of the above olive section accurate, the resulting calendar age for the last ring ranges between 1608-1589 BCE (68.3% confidence) and 1616-1576 BCE (95.4% confidence) with a peak at ca. 1600 BCE.

C04_P08

High precision dating of a Neolithic wooden trackway from Lower Saxony, Germany, using radiocarbon wiggle matching

Rose H¹, Brozio J², Shindo L³, Meadows J^1,4, Feeser I², Dörfler W², Heumüller M⁵

¹Zentrum für Baltische und Skandinavische Archäologie (ZBSA), Schleswig, Germany, ²Institute of Pre- and Protohistoric Archaeology, University of Kiel, Kiel, Germany, ³ROOTS Cluster of Excellence , University of Kiel, Kiel, Germany, ⁴Leibniz-Laboratory for Radiometric Dating and Stable Isotope Research, University of Kiel, Kiel, Germany, ⁵Lower Saxony State Office for Heritage, Hannover, Germany

Wooden trackways dating from the Neolithic to the medieval period are well-documented in Europe. The earliest finds date to the middle of the 5th millennium BC and are linked to the invention of wheeled wagons, which are known in northern Germany from 3400 BC. We present new results from a wooden trackway found east of Aschener Moor in Lower Saxony, Germany. It was discovered in the 1890s and a 100-meter-long section was excavated in the 1980s. We returned to the site in 2021 and excavated a smaller section left untouched by the earlier campaign. The trackway is wide enough to allow passage of a wagon, but it is unclear where it led; across the marshy area of the Aschener Moor would be an obvious possibility, but previous attempts to prove this have been unsuccessful. The trackway is constructed of wooden trunks placed diagonally in two layers, consisting primarily of alder (Alnus sp.), but with a smaller number of birch (Betula sp.). This excludes traditional dendrochronological dating, but using radiocarbon wiggle matching, we have dated the felling date of one alder trunk to a 20-year-window in the mid-25th century BC. Such a precise date is rare for the Neolithic period, but it is supported by chronological modelling of dates on branch wood found between the trackway logs. On-site palaeoenvironmental analyses relate the trackway construction to its local environment and periods of increasing precipitation. We will also compare our findings to the chronology of other wooden trackways in northern Europe.

C04_P09

Origin and age of carbon in cellulose of mid-latitude tree rings

Kromer B¹, Wacker L², Friedrich M³, Lindauer S⁴, Friedrich R⁴, Treydte K⁵, Fonti P⁵, Martinez E⁵

¹Institute of Environmental Physics, Heidelberg, Germany, ²Laboratory of Ion Beam Physics, ETH Zurich, Zurich, Switzerland, ³University of Hohenheim, Stuttgart, Germany, ⁴Curt-Engelhorn-Centre Archaeometry, Mannheim, Germany, ⁵WSL Birmensdorf, Birmensdorf, Switzerland

Annual rings of most trees in the middle and high latitudes are composed of the earlywood (EW), formed at the beginning of the growing season, and the latewood (LW), formed from summer onwards. A substantial part of EW in ring-porous deciduous tree species is formed before budburst, i.e. before leaves or needles have unfolded, which is a prerequisite for uptake of atmospheric CO₂. Hence, an essential share of carbon for the construction of EW must come from non-structural, mobile carbon sources (NSC), i.e. from reserve materials formed in the previous year or years. This naturally raises the question to what extent the carbon of an annual ring reflects the atmospheric carbon of the current year.

Here, ¹⁴C measurements on EW and LW tree-ring cellulose from deciduous tree species as well as non-deciduous species in selected years around the ¹⁴C bomb spike in the 1960s are presented. The measured ¹⁴C concentrations of the EW and to a lesser extend of the LW show significant deviations from the atmospheric ¹⁴C values at the time xylem cell wall deposition. With a simple model the fraction of NSC from reserves in addition to carbohydrates photosynthesized in the year of formation is quantified.

C04_P10

Using rapid atmospheric ¹⁴C changes to precise dating part of the floating chronology for pine tree from Józefowo (north Poland)

Wiktorowski D¹, Krąpiec M¹, Barniak J¹

¹AGH University of Science and Technology, Kraków, Poland

Miyake was the first to describe rapid and short-lasting increases of radiocarbon (¹⁴C) concentration in the annual tree rings between AD 774 and 775 and AD 993 and 994. This sudden increase of radiocarbon has been confirmed also by other scientists. Similar study has been conducted in Poland at the AGH University of Science and Technology. The results clearly show a rapid increase of ¹⁴C concentration in these years. Results of last studies confirmed that the abrupt increase in ¹⁴C concentration is also visible between 663 and 662 BC. In this period is also located the floating pine chronology for north Poland. Due to the characteristic of the sharp increase in radiocarbon concentration that occurs in this phenomena, and due to the global character of this effect, it is possible to use it for accurate dating of annual tree rings, using radiocarbon method. In practice, linking the relative dendrochronological dating and radiocarbon analysis of annual growth rings is possible to use “Wiggle matching” technique to precise determination of the calendar age. Samples from Grabie, a village near Krakow (south-easter Poland) were control series, of known calendar age and known changes of radiocarbon concentration around 660 BC. The values of these changes were compared with the values noted in samples of pine tree from Józefowo (floating pine chronology) to its precise dating (with an accuracy of up to one year). This allowed the absolute dating of tree rings from floating pine chronology, which has been so far unattainable using radiocarbon method.