A full Holocene record of transient gridded vegetation cover in Europe

Fossil pollen assemblages provide a record of past vegetation composition, both natural (climate-induced) and anthropogenic (human-induced). Pollen-based quantitative reconstruction of plant abundance (in percentage cover) require that biases due to differences between plants in pollen productivity and dispersal characteristics are corrected. Such correction is achieved by the “Regional Estimates of VEgetation Abundance from Large Sites”(REVEALS) model given that estimates of relative pollen productivity (RPPs) and fall speed of pollen (FSP) are available for the major plants building the plant cover. For details about the REVEALS model, see Sugita (2007). REVEALS estimates of the abundance of 31 taxa, 11 plant functional types (PFTs), and 3 land-cover types (LCTs) were produced for Europe at a 1˚x1˚ spatial scale for 25 consecutive time windows from 11.7 ka calibrated years BP* to present as part of the Swedish Research Council (VR) research project “LandClimII”. This is the second generation (version June 2021) of REVEALS reconstruction for Europe; it is based on a total of 1128 pollen records from pollen databases/archives and individual authors (See LandClimII Contributors). The first generation was published in Trondman et al. (2015) and Gaillard (2019). These pollen-based REVEALS estimates of land cover are currently used to quantify the effects of the biogeophysical forcing induced by human deforestation on the regional climate of Europe at 6 ka and 2.5 ka BP (VR LandClim II project), and to evaluate and revise the scenarios of anthropogenic land-cover change (ALCC) HYDE (Klein Goldewijk et al., 2017) and KK10 (Kaplan et al., 2009; 2011) .

The gridded pollen-based REVEALS reconstructions cover Europe (30°-75°N, 25°W-50°E) and were performed at a spatial scale of 1° × 1° (ca. 100 km × 100 km), which is the estimated spatial scale of REVEALS plant-cover estimates using all available pollen records (1128) within a grid cell and all pollen counts within each time window to ensure reliable estimates of plant cover and minimize their error estimates. The REVEALS estimates and standard errors were reconstructed for 25 time windows covering the Holocene i.e. X to 100 BP, 100 – 350 BP, 350 – 700, 700 – 1200, 1200 -1700 BP and in 500 consecutive time windows from here to 11,700 BP (BP – before present (1950)). The RPP and FSP values used in this REVEALS reconstruction are found in csv table Taxa_to_PFT, PPE and FSP values. All details of the protocol used for this REVEALS reconstruction can be found in Trondman et al. (2015). All REVEALS estimates and their SEs are given in proportions of the grid cell (the total of all REVEALS estimates sum up to 1). There are 25 files labelled TW.(number of time window).RVestimates.jun21.csv and 25 files labelled TW.(number of time window).standarderrors.jun21.csv. The RVestimates.csv files contain the REVEALS estimates for each land-cover type (LCT), plant function type (PFT) and taxa which has a unique grid ID and corresponding longitude and latitude. The standard error csv files contain the standard errors for each land-cover type (LCT), plant function type (PFT) and taxa. * BP = before present (1950). The information about the quality (previously referred to as reliability (Trondman et al. 2015)) of the REVEALS estimates in each grid cell is provided in the GC_quality_by_TW.xlsx file. There are 3 categories i.e. 1 is high quality ( 1 or more large lakes, OR 2 or more sites of any site type), 2 is low quality (only 1 small lake, OR small bog OR large bog) and no data. Extra information about each site is provided in the metadata file.