Palaeobiological evidence for Southern Hemisphere Younger Dryas and volcanogenic cold periods

Current consensus places a Southern Hemisphere post-glacial cooling episode earlier than the Younger Dryas in the Northern Hemisphere. New Zealand sequences of glacial moraines and speleothem isotopic data are generally interpreted as supporting the absence of a Southern Hemisphere Younger Dryas. Radiocarbon age series of habitat specialist moa (Aves: Dinornithiformes) show, however, that a sudden return to glacial climate in central New Zealand contemporary with the Younger Dryas. The cooling followed significant warming, not cooling, during the period of the Antarctic Cold Reversal. In addition, the moa sequence chronology also shows that the Oruanui (New Zealand) and Mt Takahe (Antarctica) volcanic eruptions were contemporary with abrupt cooling events in New Zealand. The independent high spatial and temporal resolution climate chronology reported here is contrary to an inter-hemispheric post-glacial climate see-saw model.

Cranial materials from the Oglakhty burial ground

In this article means of cranial measurements and indexes of the Tashtyk sample from the Oglakhty burial ground obtained as a result of analysis and integration of the measurements of G. Debets, V. Alexeev and I. Gokhman are presented. Also we updated the means of the pooled Tashtyk sample. It was demonstrated that the Oglakhty cranial sample cover the whole spectrum of variability of the Tashtyk population. The data on 37 male and 35 female Early Iron Age series of the Tashtyk culture, Early Tes tombs, Tes flat-grave burial grounds, Podgornovo, Bidzha, and Saragashen stages of the Tagar culture, were subjected to canonical variate analysis. The results of the analysis reveals that Tashtyk male and female series are very similar to the Early Tes samples mainly due to higher cranial index in both male and female samples and smaller nose protrusion angle in male sample. Describing the variety of options for postmortem trepanations of the Tashtyk skulls, we argue that the trepanation process was not a ritual in itself, but was a routine procedure aimed at extracting the brain.

SUCCESSION DYNAMICS OF NATIVE SPRUCE FORESTS OF DIFFERENT AGES IN EUROPEAN RUSSIA

Relevance. The article discusses various options for assigning forest biogeocenoses to a certain dynamic position in the successional field of their development. The proposed method for dynamic assessment of the position of forest creates the possibility of assessing the total movement of tree volumes in the age generations of the age range of the forest biogeocenosis the possibility of analyzing the past changes in the age structure of the biogeocenosis and predicting its future development for a very distant future. Material and methods. The objects of research are native virgin spruce biogeocenoses of different ages in the northern taiga of the Kandalaksha forestry enterprise of the Nyamozersky forestry of the Murmansk region, the Severodvinsky forestry enterprise of the Arkhangelsk region; middle taiga spruce forests of the Vepssky forest reserve, Leningrad region. and the tract “Atleka” of the Andomsky forestry of the Vologda region; southern taiga spruce forests of the Kologrivsky forest reserve Kostroma region and the Central Forest Biosphere Reserve in the Tver region. The author studied the features of the structures of the age series of spruce forests, the most typical and productive types of growing conditions for spruce. Results and conclusions. All represented forest communities have different ratios of the number and volume of trees in the age generations of the age series and, as a consequence, different positions in the successional dynamics of development. Wood-destroying fungi of the biotrophic complex, as an endogenous structure of the forest community, actively participates in the dynamic processes of its development at all stages of its successional movement. The infection of trees by fungi of this complex increases from the last generations to the first to the maximum values in the oldest trees of the first generation. The dynamic position of the indigenous virgin forest community of different ages can be described with a wider range of assessments of the dynamics of its development in retrospect and perspective in terms of the ratio of quantitative and volumetric indicators of age generations of age series than in terms of the current structure of the age series. When assessing the successional stage of the forest community, it is necessary to take into account the quantity (volumes) and structure of the deadwood.

Characterization of Diameter Distribution and Prediction of Weibull Parameters Equation for Plantation-grown Eucalyptus Species

Aim: To characterization of the diameter distribution and prediction of Weibull parameters of a plantation-grown Eucalyptus species. Study design: Stratified sampling method was adopted, in which the plantation was stratified into four age series. Place and duration of study: Afaka Forest Reserve, one month. Methodology: Fifty (50) sample plots of 20 x 20 m were laid across the age series. In each of the plot, all the trees were counted and data of variable of interest was collected and processed. A separate Weibull distribution is fitted to the diameter at breast height (dbh) frequency data from each of the plot for the estimation of Weibull parameters (location, scale and shape). The data set obtained from the Weibull parameter estimate was then used to develop regression equations with the stand variables. Coefficient of Determination (R2) and Root Mean Square Error (RMSE) was used as goodness of fit test. Results: The result on the stand characteristics revealed that, the mean diameter at breast height (dbh) ranges between 13.4 – 18.2 cm across the four stands. This indicates that the species are still of pole sizes. The average site productivity of the species ranges between 24.0 m to 37 m at an index of 25 years. The mean Basal area varies between 14.13 to 26.85 m2 per ha, while the average tree total height ranges between 24.6 to 28.2 m across the four species. The result on diameter class distribution shows that most of the species fell within dbh class of 11 -20 cm class except E. cloeziana in which the highest frequency fell into 16 – 20cm dbh class. Best equation were selected for each of the Weibull parameters (α, β, ) per species based on fit statistics. The formation of straight line pattern from the plotted normal probability plots indicates the adequacy of the selected models for predicting Weibull parameters. A fluctuation pattern exists between the Weibull parameters and the stand characteristics. this may be due to variation in climatic factor, most especially fluctuations in rainfall pattern in the area at that particular period. Conclusion: The ease of fit and high value of coefficient of determination of the models in this study has re-affirmed the use of Weibull parameter in prediction of stand characteristics as been suggested by many authors in the literature.

Evidence for old carbon contamination in ¹⁴C wiggle-match age series for the 946 CE eruption of Changbaishan volcano

Volcanic eruptions that are not historically attested are commonly radiocarbon dated by "wiggle matching" sequential 14C measurements of the rings of trees killed by the eruption against an accepted calibration curve. It is generally assumed that carbon laid down in the wood is uncontaminated by 14C-free ("old") carbon, although evidence for contamination is well documented. Often, ill-fitting ring ages are excluded from analysis. The ‘Millennium Eruption' of Changbaishan volcano on the China-DPR Korea border offers a valuable case study in wiggle match dating, since several independent groups reported age estimates before the determination and acceptance of a precise eruption year of 946 CE. Some of the discrepancies and incompatibilities between published dates were attributed to old carbon effects. Here, we apply a new methodology to correct for contamination levels of up to 4.5% old carbon to eight wiggle match date series for the Millennium Eruption. Without discarding ring ages, we find agreement indices as high as, or higher than, those for the published dates, and five of the eight date series yielded high-agreement-index eruption dates closer to 946 CE than the published dates. None of the five yield a best result at zero contamination. Differences between the eruption dates reveal a weak association with the direction of the sampled tree from the caldera, but no relationship with distance. Our results suggest that old carbon contamination is possible over a wide area, potentially leading to over-estimation of eruption ages by years, decades or more, cautioning against over-reliance on wiggle-match ages that are not corroborated by other lines of evidence. Our revised protocol that accounts for contamination offers a way forward in the application of wiggle match dating of eruptions and provides a platform for understanding discrepancies that exist when comparing wiggle match series.

Age Sequence Recursive Models for Long Time Evaluation Problems

The evaluation models for long time historical data is important in many applications. In this study, based on Age measure defined by Yager, we propose the definitions of Age Sequence and Age Series. Then, we provide a Generalized Recursive Smoothing method. Some classical smoothing models in evaluation problems can be seen as special cases of Generalized Recursive Smoothing method. In order to obtain more reasonable and effective aggregation results of the historical data, we propose some different Age Sequences, e.g., the Generalized Harmonic Age Sequence and p Age Sequence, which theoretically can provide infinite more recursive smoothing methods satisfying different preferences of decision makers.