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We compile a data set of forest surveys from expeditions to the north-east of the Russian Federation, in Krasnoyarsk Krai, the Republic of Sakha (Yakutia) and the Chukotka Autonomous Okrug (59-73° N, 97-169° E). The region is characterized by permafrost soils, and forests dominated by larch (Larix gmelinii RUPR., Larix cajanderi MAYR). Our dataset consists of a plot data base describing 226 georeferenced vegetation survey sites, and of a tree data base with information about all trees on these plots. The tree data base contains information on height, species and vitality of 40,289 trees. A subset of the trees was subject to a more detailed inventory, recording stem diameter at base and at breast height, crown diameter and height of the beginning of the crown. We recorded heights up to 28.5 m (median = 2.5 m) and stand densities up to 120,000 trees per ha (median = 1197 ha-1), both values tending to be higher in the more southerly areas. Observed taxa include Larix MILL., Pinus L., Picea A.DIETR., Abies MILL., Salix L., Betula L., Populus L., Alnus MILL. and Ulmus L.. In this study, we present the forest inventory data aggregated per site. Additionally, we connect it with different remote sensing data products to find out how accurately forest structure can be predicted from such products. Allometries were calculated to obtain the diameter from height measurements for every species group. For Larix, the most frequent of ten species groups, allometries depend also on the stand density, as denser stands are characterized by thinner trees, relative to height. The remote sensing products used to compare against the inventory data include climate, forest biomass, canopy height, and forest loss or disturbance. We find that the forest metrics measured in the field can only be reconstructed from the remote sensing data to a limited extent, as they depend on local properties. This illustrates the need for ground inventories like those data we present here. The data can be used for studying the forest structure of north-eastern Siberia, and for the calibration and validation of remotely sensed data. [ABSTRACT FROM AUTHOR]

Abstract Pollen productivity estimates (PPEs) are fractionate values of relative pollen productivity, often in relation to Poaceae, that allow vegetation cover to be estimated from pollen counts. PPEs are especially used in the European and Chinese scientific community, with a few studies in North America. Here we present a comprehensive compilation of available PPE studies and their results arising from 40 publications with 49 sites and 99 taxa. This compilation allows scientists to identify the best PPE for their own studies and to identify data-gaps in need of further PPE analyses. We also present a taxonomically harmonised, unified PPE dataset, which we generated from the available studies. Studies which did not have Poaceae as reference taxon were not included unless they included taxa which would otherwise drop out of the dataset. The unified dataset is based on 30 publications and 34 sites, and gives the mean PPE per taxon excluding outliers as well as fall speeds, which are necessary to reconstruct vegetation cover from pollen counts and PPE values. It contains 58 PPEs and 57 fall speeds, with 54 taxa having values for both. This dataset can be applied to broad scale or long-term pollen-vegetation analyses. [ABSTRACT FROM AUTHOR]

Pollen records from Siberia are mostly absent in global or Northern Hemisphere synthesis works. Here we present a taxonomically harmonized and temporally standardized pollen dataset that was synthesized using 173 palynological records from Siberia and adjacent areas (northeast Asia, 50°–180° E and 42°–75° N). Pollen data were taxonomically harmonized, that is the original 437 taxa were transformed to 106 combined pollen taxa. Age-depth models for all records were revised by applying a constant Bayesian age-depth modelling routine. The pollen dataset is available as count data and percentage data in a table format (taxa vs. samples) with age information for each sample. The dataset has relatively few sites covering the last glacial period between 40 and 11.5 cal ka BP (calibrated thousand years before present 1950 CE) particularly from the central and western part of the study area. In the Holocene period, the dataset has many sites from most of the area except the central part of Siberia. Of the 173 pollen records, 81 % of pollen counts were downloaded from open databases (GPD, EPD, Pangaea) and 10 % were contributions of the original data gatherers, while a few were digitized from publications. Most of the pollen records originate from peatlands (48 %) and lake sediments (33 %). Most of the records (83 %) have ≥ 3 dates allowing the establishment of reliable chronologies. The dataset can be used for various purposes including pollen data mapping (example maps for Larix at selected time-slices are shown) as well as quantitative climate and vegetation reconstructions. The datasets for pollen counts and pollen percentages are available at https://doi.pangaea.de/10.1594/PANGAEA.898616 (Cao et al., 2019). [ABSTRACT FROM AUTHOR]