Annotation of the results obtained in 2021
During the first year of the project, 1,140 samples were сollected: 466 samples from living trees, 247 samples from wooden buildings and 427 archaeological samples. The blue intensity (blue intensity of late wood BI and the difference in the blue intensity of late and early wood δBI) of 341 cores was measured for the Arkhangelsk, Vologda, Leningrad, Kostroma and Yaroslavl regions. It is shown that the constructed chronologies of blue intensity have high correlation coefficients with chronologies of maximum X-ray density from neighboring locations. The tree-ring width was measured for 10 sites of living trees, 10 local tree-ring chronologies up to 380 years long were constructed. The tree-ring width from 10 old buildings was measured, 10 local tree-ring chronologies up to 462 years long were constructed, 7 of them were dated. Dating, in particular, received such objects of cultural heritage as the chapel of Mary Magdalene, St. Nicholas Church from village Visokiy Ostrov and St. Nicholas Church from village Tukholi (Vitoslavlitsy Museum, Veliky Novgorod), Elijah Church (Kostroma Museum of Wooden Architecture), Bazhenov House from Vavchuga village, Arkhangelsk region. 88 samples of subfossile oak wood from the alluvial deposits of the Sura River were collected and processed, 6 floating chronologies up to 581 years long were constructed. Materials from 11 archaeological collections were measured. A total of 883 samples were measured during the first year of the project: 405 samples from living trees, 160 samples from wooden buildings, 230 archaeological samples and 88 samples of buried wood. Samples were prepared for cellular measurements. The first cellular measurements were obtained for pine trees from the Yaroslavl region. 183 cellulose samples were prepared to measure the ratio of stable carbon isotopes in annual rings. At the moment, 93 samples have been measured. A preliminary analysis of the response function for the period 2010-2020 was carried out, which showed a statistically significant response to aridity conditions.

 

Publications

---

Annotation of the results obtained in 2022
In 2022, organization of saw cut collections was completed (previously, the core collection was organized). The storage room was equipped with racks, the collections of saw cuts were placed on them. Over 1,000 saw cuts have been downsized, greatly reducing the storage space required. The created repository has enough space to replenish with new samples for at least the next 10 years. A booklet-memo on the selection of dendrochronological samples for distribution among the project volunteers was created and passed to the coordinator of the project for restoration of wooden churches. A 14-day expedition (May 28-June 10, 2022) was conducted to collect samples. The total length of the route was about 3500 km. Stands up to 300 years old were found and eight living tree plots were established. Most importantly, the samples were taken in the relatively forestless part of the Russian Plain, which expands the geographic coverage of the dendrochronological network to the south and will contribute both to the study of the climatic response of tree-ring parameters in these areas and to the developent of new composite chronologies. A total of 790 samples were collected during the second year of the project: 426 samples from living trees (10 collections), 289 samples from wooden structures (18 collections) and 75 archaeological samples (10 collections). 20 tree-ring chronologies were built for different tree species (pine, spruce, oak) with a duration of 100 years or more. During the second year of the project, samples were prepared and optical density was measured (optical density of late wood BI and the difference between optical density of late and early wood δBI) for 181 architectural wood cores from the Arkhangelsk, Novgorod, Vologda, Kostroma and Yaroslavl regions. Optical density was also measured for the first 10 archaeological samples from the Kostroma and Vologda regions. To build chronologies of cellular parameters, 23 microsections were measured for sample A22A21A. For each annual ring, we received data on 36 parameters. The length of the chronologies is132 years - 1889-2020. For the same sample plot, a chronology of stable carbon isotopes was obtained based on the measurement of 183 samples from individual tree rings and covering the period 1900–2020. Correlation analysis showed that most of the cellular parameters are characterized by significant positive correlations with the scPDSI index (r=0.36-0.47, p<0.05) during the growing season of the current year, from May to September. Significant positive correlations were obtained mainly for precipitation in May of the current year (r=0.34-0.43) and temperatures in January and February of the current year (r= from -0.25 to -0.45). We also compared the new C13 carbon isotope chronology with average monthly precipitation and air temperature. The analysis revealed a negative relationship with June and July temperatures, as well as a positive relationship with May, June and July precipitation. The relationship with the PDSI dryness index also turned out to be statistically significant for July, August and September. In general, the results obtained indicate the presence of a relationship with moisture availability. Further work to measure more series is likely to increase the tightness of the relationship. An analysis of the climatic response in the chronologies of the optical density of wood revealed the presence of a strong temperature signal in the chronologies located in the north. Thus, the optical density obtained for the territory of Solovki, the north of the Arkhangelsk and the east of the Leningrad regions depends on the variability of summer temperature (r = 0.2-0.55). At the same time, the highest correlations are observed in two pine chronologies with July, I24S and O02S from the Arkhangelsk and Leningrad regions, and reach the values r = 0.54 and 0.52. The only chronology of optical density in which no response to summer temperatures was found was A22SD, located to the south of all the other studied chronologies, in the Yaroslavl region. Three chronologies the width of annual rings BelBog, C04S, N13 from Solovki, Vologda, Novgorod regions have a positive response to winter air temperature.The value of the correlation coefficients with precipitation variability is much lower than with temperature and varies from 0.18 to 0.34. In 2022, dendrochronological analysis of samples of subfossil oak wood from alluvial deposits of the Sura River was continued. Fifty-seven new accessions were studied, some of which were identified as seven new trees, and some were included in the trees identified last year. This, in particular, forced us to reconsider the composition of one of the floating tree-ring chronologies built last year. At the present stage, the total number of studied subfossil individual trees from the Sura River is 56. Historical records of weather and climate were searched for two continuous historical periods: the entire 17th century and the first third of the 19th century (1801-1829). The main stage of the work consisted in collecting and presenting source information on the history of climate in Russia in the 17th century. This work included identifying relevant historical sources; systematic review of historical sources in search of news about climatic, weather, geological and astronomical phenomena; identification of relevant news; localization and dating of discovered news; a critical assessment of the information contained in the news; entering data into the table and (if necessary) drawing up an expert commentary. In the course of the work, tens of thousands of pages of historical sources of various types were systematically reviewed: narrative (chronicles, chronicles), office work (business correspondence, diplomatic, administrative and military documentation) and sources of personal origin (diaries and notes of contemporaries), as well as hundreds of pages of reference and scientific literature. The key result of the work done on the study of written sources of the 17th century was the identification and presentation in a structured tabular form of more than 300 evidence. The results of working with newspapers of the first third of the 19th century were a table with printed mentions of weather events in the news and an archive of photographs of daily meteorological observations. In total, 476 mentions of weather events were recorded for this period. Work was also carried out on the development of existing methods for the reconstruction of climatic indicators based on tree-ring data. The self calibrated Palmer drought severity index (scPDSI) and summer temperature were chosen as the considered climatic indicators. Four methods of spatial reconstruction were considered: Ensemble Point-by-point Regression (EPPR), Linear Principal Component Regression (lm), Artificial Neural Networks (ANNs), and Modified Pointwise Regression using Partial Least Squares Regression (PPR+PLSR). The last two methods were developed as part of this study. To test the proposed methods, the territory of North America was chosen, since it has the largest number of tree-ring chronologies, as well as the results of reconstructions by other authors. The results of scPDSI and temperature reconstruction based on pseudo-proxy simulation showed the superiority of the method (PPR+PLSR), while ANN showed the worst results. The linear model, which is actually a one-layer, one-node version of ANN, is worse than EPPR for scPDSI, but better for temperature, which is most likely due to the more continuous spatial distribution of temperature values, which means it is easier to describe in terms of EOF. In 2022, 6 papaers on the subject of the project were published, including 4 articles in Q1, one article in Scopus and one article in the RSCI. The declared indicators for publications were overfulfilled by 1.4 times a year before the end of the project. Three reports were presented at one international and one Russian conference.

 

Publications

---