Charcoal piles have become a frequent subject of research in recent years as a better understanding of past human activities in forests is sought. The age of charcoal piles is usually determined by ...radiocarbon dating; dendrochronology is rarely used because of the small size of preserved charcoal remains and the insufficient number of visible tree rings. This paper presents the potential for dendrochronological and 14C method in research into charcoal piles. From 14 charcoal-burning sites in the Czech Republic, 214 pieces of charcoal were anatomically identified at the genus level and dendrochronologically analysed. Our results show that fir dominated in these charcoal remains, followed by oak, beech, spruce and pine. With an overall dendrochronological dating success of 24 %, fir charcoal was dated most often (65 %) with measurable tree rings ranging from 14 to 90. The oldest charcoals were dendrochronologically dated to summer 1682 CE; conversely, the youngest had end dates in the second half of the 19th century. The relatively poor dating success of oak charcoal very likely resulted from the use of branches for charcoal production rather than tree trunks. Based on an analysis of selected charcoal samples, we confirm that radiocarbon dating provided a very wide range of dates in the post-1650 CE period and the use of the wiggle-matching method was usually challenging because of short TRW series. Based on samples with preserved waney edges, we conclude that charcoal was more commonly made from wood felled in the summer than in the winter. Despite the relatively low level of success of dendrochronological dating, it seems more effective for dating charcoal than the 14C method, especially with samples from the last 350 years.
•Fir dominated in the investigated charcoal followed by oak, beech, spruce and pine.•Success of dendrochronological dating of charcoals was 24 %.•Oak charcoal was made of branches instead of coppice shoots or tree trunks.•Charcoal was more often made from trees felled in summer than in winter.•Dendrochronological dating of charcoal is more effective than 14C method.
The warming climate of recent decades has led to further aridity of the Mongolian landscape and has had major effects on forest growth and wildfire occurrence. Here, we investigated drought and ...wildfire effects on the growth of Pinus sylvestris along an ecologically diverse transect in semiarid north-central Mongolia using two separate subsets. Tree-ring width series of the first subset, represented by trees without fire scars, were clustered into three regional chronologies reflecting environmental differences of delineated geo-vegetation zones. Tree-ring growth reflected June drought signal at all three zones. The increasing radial growth trend was found in the dark taiga zone, likely supported by permafrost summer thawing, primarily caused by temperature increases. The second subset, represented by injured trees, showed that most wildfires occurred during the dormant season and in the forest-steppe zone; April–May drought conditions substantially contributed to triggering wildfires. Nevertheless, an increased frequency of wildfires in the study area was not observed, despite temperature increases since 1940. Our study highlights the significance of the effect of the ongoing temperature increase on north-central Mongolian pine forests, and, correspondingly, the need to conserve an endangered ecosystem of the dark taiga and to undertake afforestation activities in devastated pine forests.
•We evaluate the long-term Pinus sylvestris growth in north-central Mongolia.•TRW variability reflects the tree distribution into three geo-vegetation zones.•Scots pine climate sensitivity reflects significant June drought signals at all zones.•The most drought limited pines showed a significantly decreasing growth trend.•Spring drought conditions contributed to the triggering of the wildfires.
Polarization transfer to a bound proton in polarized electron knock-out reactions, A(e→,e′p→), is a powerful tool to look for an in-medium modification of the bound proton. It requires comparison to ...calculations that consider the many-body effects accompanying the quasi-free process. We report here measured components Px′, Pz′, and their ratio Px′/Pz′, of polarization transfer to protons bound in Ca40, which is described well by the shell model and for which reliable calculations are available. While the calculations capture the essence of the data, our statistical precision allows us to observe deviations that cannot be explained by simple scaling, including by varying the proton electromagnetic form factor ratio GE/GM. We further explore the deviations of the ratio of the polarization transfer components from that of a free proton, (Px′/Pz′)A/(Px′/Pz′)H, and its dependence on the bound-proton virtuality.
Transcarpathian wooden churches started to dilapidate after World War I. To preserve the architectural heritage, five oak churches were transported from the region to the territory of today's Czech ...Republic. However, an exact date of their construction and origin of wood have not been specified and evidenced in literature. In this study, 63 samples have been collected and processed using standard dendrochronological methods. Three Baroque churches, coming from the Mukachevo district, were absolutely dated thanks to the preserved waney edge or sapwood tree rings to periods 1734–1744, 1753–1755, and 1783–1795. Two other churches, representing Gothic architecture, were transported from a more eastern part of Transcarpathian Ukraine. One of them was dated to the period after 1655 and the other could not be reliably dated using available reference chronologies. The created mean tree-ring width series representing individual churches showed strong correlations with the reference chronologies for Slovakia and northern Romania whereas correlations with the only Ukrainian chronology (Lviv region) were negligible. This could suggest low Transcarpathian tree-ring coherency and may indicate the need to create a dense network of regional tree-ring width chronologies in the regions surrounding the Carpathian Mountains.
•Five oak churches were transported from Transcarpathia to the Czech territory.•The churches were built during the second half of the 17th and the 18th centuries.•The Ukrainian churches were dated using Slovakian and Romanian TRW chronologies.•Compilation of oak TRW chronology for Transcarpathia is pivotal for precise dating.
The Early Triassic is a critical interval for the study of recovery from the terminal Permian mass extinction, as there are small-scale extinction events, which may have contributed to the delayed ...recovery. The systematic measuring and sampling of a 12-m-thick section at the Mokrice locality in eastern Slovenia has resulted in the recovery of a conodont fauna from the Olenekian beds. Four conodont zones have been recognized. These zones are in ascending order as follows: the
Hadrodontina aequabilis
Zone,
Platyvillosus corniger
Zone,
Platyvillosus regularis
Zone, and
Triassospathodus hungaricus
Zone. These conodont zones confirm the proposed conodont biozonation sequence in western Slovenia and have correlation value especially for the western marginal Tethys. Multielement conodont apparatuses of
Triassospathodus hungaricus
and
Platyvillosus regularis
have been reconstructed based on conodont elements that were recently obtained from the Slovenian sections. Although the S
2
element was not found, the apparatus indicates that the conodont species “
Spathognathodus
”
hungaricus
should be assigned to the genus
Triassospathodus.
We report on the results of the first search for the production of axion-like particles (ALPs) via Primakoff production on nuclear targets, γA→aA, in the “SRC-CT” experiment using the GlueX detector ...at Jefferson Lab. This search uses an integrated luminosity of 100 pb⋅−1nucleon on a 12C target with a real photon beam of energies 6<Eγ<10.8 GeV, and explores the mass region of 200<ma<450 MeV via the decay a→γγ. This mass range is between the π0 and η meson masses, which enables the use of the measured η meson production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the effective photon coupling scale of O(1TeV−1). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant background the in GlueX spectrometer, which we treat by using data on 4He to estimate and subtract it. We comment on how this search can be improved in a future higher-statistics dedicated measurement.
A cryogenic supersonic gas jet target was developed for the MAGIX experiment at the high-intensity electron accelerator MESA. It will be operated as an internal, windowless target in the ...energy-recovering recirculation arc of the accelerator with different target gases, e.g., hydrogen, deuterium, helium, oxygen, argon, or xenon. Detailed studies have been carried out at the existing A1 multi-spectrometer facility at the electron accelerator MAMI. This paper focuses on the developed handling procedures and diagnostic tools, and on the performance of the gas jet target under beam conditions. Considering the special features of this type of target, it proves to be well suited for a new generation of high-precision electron scattering experiments at high-intensity electron accelerators.
We present the first measurements of the double ratio of the polarization-transfer components (Px′/Pz′)p/(Px′/Pz′)s for knock-out protons from the s and p shells in C12 measured by the C12(e→,e′p→) ...reaction in quasi-elastic kinematics. The data are compared to theoretical predictions in the relativistic distorted-wave impulse approximation. Our results show that the differences between s- and p-shell protons, observed when compared at the same initial momentum (missing momentum), largely disappear when the comparison is done at the same proton virtuality. We observe no difference in medium modifications between protons from the s and p shells with the same virtuality in spite of the large differences in the respective nuclear densities.
Longstanding demographic growth accompanied by rising settlement activities and development of industry led to an increasing demand on utilization of wood. Tree species were selected for their ...specific properties. As a consequence of regional differences of forest species composition, wood has become an extremely important trade commodity. Therefore, the utilization of individual species could substantially change in space and time. In this study, we use 8´135 precisely dated timber constructions from a dendrochronological database to investigate spatio-temporal changes in wood utilization across the Czech lands from the 15th to the 19th century. Our results suggest that the utilization of individual species in historical timber constructions was primarily limited by their availability. Species selection was also based on wood properties and stem geometry. Most of historical constructions (99.7%), represented mainly by roofs and ceilings, are made of fir, spruce, pine, and oak. While fir constructions prevail in eastern Moravia and Silesia, spruce constructions are largely spread across the western and central part of the Czech Republic. Pine and oak constructions reflect natural occurrence of such forests in lower elevated central Bohemia and southern Moravia. Although fir prevailed in timber construction in the late-Medieval and post-Medieval times, planting of spruce monocultures resulted in its significantly increased utilization by the end of the 19th century. This study demonstrates the value of dendrochronological databases as an indicator of historical wood utilization.
•Most of the 8´135 historical constructions are made of fir, spruce, pine and oak.•Easy availability of tree species was pivotal for their use in the 1400–1900 period.•Wood properties and stem geometry was crucial in species selection as well.•Fir prevailed until the 18th century, while spruce prevailed from the 19th century.•Pine and oak utilization reflect their natural distribution in the Czech lands.
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