European Forest Cover During the Past 12,000 Years: A Palynological Reconstruction Based on Modern Analogs and Remote Sensing

Abstract

Characterization of land cover change in the past is fundamental to understand the evolution and present state of the Earth system, the amount of carbon and nutrient stocks in terrestrial ecosystems, and the role played by land-atmosphere interactions in influencing climate. The estimation of land cover changes using palynology is a mature field, as thousands of sites in Europe have been investigated over the last century. Nonetheless, a quantitative land cover reconstruction at a continental scale has been largely missing. Here, we present a series of maps detailing the evolution of European forest cover during last 12,000 years. Our reconstructions are based on the Modern Analog Technique (MAT): a calibration dataset is built by coupling modern pollen samples with the corresponding satellite-based forest-cover data. Fossil reconstructions are then performed by assigning to every fossil sample the average forest cover of its closest modern analogs. The occurrence of fossil pollen assemblages with no counterparts in modern vegetation represents a known limit of analog-based methods. To lessen the influence of no-analog situations, pollen taxa were converted into plant functional types prior to running the MAT algorithm. We then interpolate site-specific reconstructions for each timeslice using a four-dimensional gridding procedure to create continuous gridded maps at a continental scale. The performance of the MAT is compared against methodologically independent forest-cover reconstructions produced using the REVEALS method. MAT and REVEALS estimates are most of the time in good agreement at a trend level, yet MAT regularly underestimates the occurrence of densely forested situations, requiring the application of a bias correction procedure. The calibrated MAT-based maps draw a coherent picture of the establishment of forests in Europe in the Early Holocene with the greatest forest-cover fractions reconstructed between ∼8,500 and 6,000 calibrated years BP. This forest maximum is followed by a general decline in all parts of the continent, likely as a result of anthropogenic deforestation. The continuous spatial and temporal nature of our reconstruction, its continental coverage, and gridded format make it suitable for climate, hydrological, and biogeochemical modeling, among other uses.

Forest Landscape Change and Preliminary Study on Its Driving Forces in Ślęża Landscape Park (Southwestern Poland) in 1883–2013

“…Changes in forest landscapes and those in the immediate vicinities of forests [16][17][18][19] are particularly noticeable. The results of palaeoenvironmental studies [20], used also as primary source for the reconstruction of forest cover [21], have more and more often become the starting point for research on long-term landscape changes. So far, in many cases, landscape change studies have been limited only to identifying the sizes and types of transformations, ignoring the identification of factors that could have a significant impact on the landscape.…”

Development and testing scenarios for implementing land use and land cover changes during the Holocene in Earth system model experiments

“…Maps of the distribution of archaeological sites or of areas linked to a given food production system have been produced for individual site catchments or small regions (e.g. Zimmermann et al, 2009;Barton et al, 2010;Kay et al, 2019). LandCover6k is developing global land use maps for specific time windows using a global hierarchical classification of land use categories (Morrison et al, 2018) based on land use types that are widely recognized from the archaeological record.…”

Development and testing of scenarios for implementing Holocene LULC in Earth System Model Experiments

“…It may also be possible to use alternative pollen-based reconstructions of land cover changes (e.g. Tarasov et al, 2007;Fyfe et al, 2014;Dawson et al, 2016;Zanon et al 2018).…”