Tree pollen representation in surface pollen assemblages from different vegetation zones of European Russia

The paper presents the results of studies of 270 modern pollen assemblages from different vegetation zones of the East European plain. According to obtained data the ratio of the main components in pollen assemblages from forest and forest-steppe localities is characterized by higher proportion of the regional components (e.g., Betula, Alnus, Pinus) and significantly lower participation of Picea pollen and one of deciduous trees then the proportions of these species in the surrounding vegetation. Steppe vegetation is determined by higher share of non- arboreal pollen and specific floristic composition. The comparison between geographical range of tree species and maps showing distribution of their pollen show a possibility a long distance transfer of Carpinus and Fagus pollen while pollen of Quercus and Tilia occurred close to their modern geographical ranges

Forest history, peatland development and mid- to late-Holocene environmental change in the southern taiga forest of central European Russia

Understanding the long-term ecological dynamics of boreal forests is essential for assessment of the possible responses and feedbacks of forest ecosystems to climate change. New data on past forest dynamics and peatland development were obtained from a peat sequence in the southern Valdai Hills (European Russia) based on pollen, plant macrofossil, micro-charcoal, peat humification, and testate amoeba analyses. In terms of vegetation history, the results demonstrate a dominance of broadleaved forests in the study area from 7000 4000 cal yr BP. Picea was initially a minor component of this forest but increased in cover rapidly with climatic cooling beginning at 4000 cal yr BP, becoming the dominant species. Broadleaved species persisted until 900 cal yr, with evidence for intensified felling and forest management over recent centuries. Over the last four hundred years there is evidence for widespread paludification and the establishment of Picea-Sphagnum forests. These data demonstrate how modern wet woodlands have been shaped by a combination of climatic and anthropogenic factors over several millennia. The results also demonstrate the value of a multiproxy approach in understanding long-term forest ecology

Изменения окружающей среды в позднеледниковье и голоцене на юго-востоке Беларуси

Communicated by Academician Aleksey V. MatveevThe reconstruction of environmental changes in the southeast of Belarus during the last 14700 cal. BP is based on the results of palynological, radiocarbon, isotope and lithological studies of Lake Staroje deposits. Climatic fluctuations, fires and human activities played a significant role in the transformation of the vegetation cover. The beginning of the lacustrine sedimentation was dated circa 16000 cal. BP. The intensification of erosion processes on the water catchment area was marked by an increase in the mineral material flow into the lake. These events have a positive correlation with the climate cooling and humidity phases in the Late Glacial and Early Holocene, and in the Late Holocene with anthropogenic impact stages. The traces of the episodic human activity were dated to 5800 cal. BP, while the expansion of farming and pasturing areas began at 3000 cal. BP Currently the consequences of human activities (including drainage of bogs) are reflected in the treeless landscapes adjacent to the lake.Представлено академиком А. В. МатвеевымРеконструкция изменений окружающей среды на юго-востоке Беларуси в течение последних 14,7 тыс. кал. л. н. основана на результатах палинологических, радиоуглеродных, изотопных и литологических исследований отложений оз. Старое. Климатические колебания, пожары и деятельность человека играли значительную роль в преобразовании растительного покрова. Начало озерного седиментогенеза датируется около 16,0 тыс. кал. л. н. Усиление эрозионных процессов на водосборе было отмечено повышенным поступлением минерального материала в озеро. Эти события в позднеледниковье и раннем голоцене имеют положительную корреляцию с фазами похолодания и увлажнения климата, а в позднем голоцене с этапами антропогенного воздействия. Следы эпизодической деятельности человека установлены с ~5,8 тыс. кал. л. н., а начало земледелия и расширение пастбищных площадей с 3,0 тыс. кал. л. н. В настоящее время последствия хозяйственной деятельности человека (включая осушение болот) иллюстрируют безлесные ландшафты, прилегающие к озеру

LegacyClimate 1.0: A dataset of pollen-based climate reconstructions from 2594 Northern Hemisphere sites covering the late Quaternary

Here we describe the LegacyClimate 1.0, a dataset of the reconstruction of mean July temperature (TJuly), mean annual temperature (Tann), and annual precipitation (Pann) from 2594 fossil pollen records from the Northern Hemisphere spanning the entire Holocene with some records reaching back to the Last Glacial. Two reconstruction methods, the Modern Analogue Technique (MAT) and Weighted-Averaging Partial-Least Squares regression (WA-PLS) reveal similar results regarding spatial and temporal patterns. To reduce the impact of precipitation on temperature reconstruction and vice versa, we also provide reconstructions using tailored modern pollen data limiting the range of the corresponding other climate variables. We assess the reliability of the reconstructions using information from the spatial distributions of the root-mean squared error of prediction and reconstruction significance tests. The dataset is beneficial for climate proxy synthesis studies and to evaluate the output of climate models and thus help to improve the models themselves. We provide our compilation of reconstructed TJuly, Tann, and Pann as open-access datasets at PANGAEA (https://doi.pangaea.de/10.1594/PANGAEA.930512; Herzschuh et al., 2021). R code for the reconstructions is provided at Zenodo (https://doi.org/10.5281/zenodo.5910989; Herzschuh et al., 2022), including harmonized open-access modern and fossil datasets used for the reconstructions, so that customized reconstructions can be easily established

Fire hazard modulation by long-term dynamics in land cover and dominant forest type in eastern and central Europe

Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding the risk of fires is quantifying the mediating effect of vegetation on fire regimes. Here, we explore the relative importance of Holocene land cover, land use, dominant functional forest type, and climate dynamics on biomass burning in temperate and boreo-nemoral regions of central and eastern Europe over the past 12 kyr. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and statistical modelling. Biomass burning was highest during the early Holocene and lowest during the mid-Holocene in all three ecoregions (Atlantic, continental and boreo-nemoral) but was more spatially variable over the past 3–4 kyr. Although climate explained a significant variance in biomass burning during the early Holocene, tree cover was consistently the highest predictor of past biomass burning over the past 8 kyr. In temperate forests, biomass burning was high at ~ 45% tree cover and decreased to a minimum at between 60% and 70% tree cover. In needleleaf-dominated forests, biomass burning was highest at ~60 %–65%tree cover and steeply declined at > 65% tree cover. Biomass burning also increased when arable lands and grasslands reached ~15 %–20 %, although this relationship was variable depending on land use practice via ignition sources, fuel type and quantities. Higher tree cover reduced the amount of solar radiation reaching the forest floor and could provide moister, more wind-protected microclimates underneath canopies, thereby decreasing fuel flammability. Tree cover at which biomass burning increased appears to be driven by warmer and drier summer conditions during the early Holocene and by increasing human influence on land cover during the late Holocene. We suggest that longterm fire hazard may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene

Significance testing testate amoeba water table reconstructions

Transfer functions are valuable tools in palaeoecology, but their output may not always be meaningful. A recently-developed statistical test ('randomTF') offers the potential to distinguish among reconstructions which are more likely to be useful, and those less so. We applied this test to a large number of reconstructions of peatland water table depth based on testate amoebae. Contrary to our expectations, a substantial majority (25 of 30) of these reconstructions gave non-significant results (P > 0.05). The underlying reasons for this outcome are unclear. We found no significant correlation between randomTF P-value and transfer function performance, the properties of the training set and reconstruction, or measures of transfer function fit. These results give cause for concern but we believe it would be extremely premature to discount the results of non-significant reconstructions. We stress the need for more critical assessment of transfer function output, replication of results and ecologically-informed interpretation of palaeoecological data

Regional variability in peatland burning at mid- to high-latitudes during the Holocene

Acknowledgements This work developed from the PAGES (Past Global Changes) C-PEAT (Carbon in Peat on EArth through Time) working group. PAGES has been supported by the US National Science Foundation, Swiss National Science Foundation, Swiss Academy of Sciences and Chinese Academy of Sciences. We acknowledge the following financial support: UK Natural Environment Research Council Training Grants NE/L002574/1 (T.G.S.) and NE/S007458/1 (R.E.F.); Dutch Foundation for the Conservation of Irish Bogs, Quaternary Research Association and Leverhulme Trust RPG-2021-354 (G.T.S); the Academy of Finland (M.V); PAI/SIA 80002 and FONDECYT Iniciación 11220705 - ANID, Chile (C.A.M.); R20F0002 (PATSER) ANID Chile (R.D.M.); Swedish Strategic Research Area (SRA) MERGE (ModElling the Regional and Global Earth system) (M.J.G.); Polish National Science Centre Grant number NCN 2018/29/B/ST10/00120 (K.A.); Russian Science Foundation Grant No. 19-14-00102 (Y.A.M.); University of Latvia Grant No. AAp2016/B041/Zd2016/AZ03 and the Estonian Science Council grant PRG323 (TrackLag) (N.S. and A.M.); U.S. Geological Survey Land Change Science/Climate Research & Development Program (M.J., L.A., and D.W.); German Research Foundation (DFG), grant MA 8083/2-1 (P.M.) and grant BL 563/19-1 (K.H.K.); German Academic Exchange Service (DAAD), grant no. 57044554, Faculty of Geosciences, University of Münster, and Bavarian University Centre for Latin America (BAYLAT) (K.H.K). Records from the Global Charcoal Database supplemented this work and therefore we would like to thank the contributors and managers of this open-source resource. We also thank Annica Greisman, Jennifer Shiller, Fredrik Olsson and Simon van Bellen for contributing charcoal data to our analyses. Any use of trade, firm, or product name is for descriptive purposes only and does not imply endorsement by the U.S. Government.Peer reviewedPostprin

The Eurasian Modern Pollen Database (EMPD), version 2

The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60 % from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019)Swiss National Science Foundation | Ref. 200021_16959