Deforesting Europe: pollen-inferred Holocene land cover change using the 'pseudobiomization' approach

Maps of continental-scale land cover are utilized by a range of diverse users but whilst a range of products exist that describe present and recent land cover in Europe, there are currently no datasets that describe past variations over long time-scales. User groups with an interest in past land cover include the climate modelling community, socio-ecological historians and earth system scientists. Europe is one of the continents with the longest histories of land conversion from forest to farmland, thus understanding land cover change in this area is globally significant. This study applies the pseudobiomization method (PBM) to 982 pollen records from across Europe, taken from the European Pollen Database (EPD) to produce a first synthesis of pan-European land cover change for the period 9000 BP to present, in contiguous 200 year time intervals. The PBM transforms pollen proportions from each site to one of eight land cover classes (LCCs) that are directly comparable to the CORINE land cover classification. The proportion of LCCs represented in each time window provides a spatially aggregated record of land cover change for temperate and northern Europe, and for a series of case study regions (western France, the western Alps, and the Czech Republic and Slovakia). At the European scale, the impact of Neolithic food producing economies appear to be detectable from 6000 BP through reduction in broad-leaf forests resulting from human land use activities such as forest clearance. Total forest cover at a pan-European scale moved outside the range of previous background variability from 4000 BP onwards. From 2200 BP land cover change intensified, and the broad pattern of land cover for preindustrial Europe was established by 1000 BP. Recognizing the timing of anthropogenic land cover change in Europe will further the understanding of land cover-climate interactions, and the origins of the modern cultural landscape.多类用户均会使用大陆尺度土地覆盖图，但当前虽已有多款可描述欧洲当前及近期土地覆盖的产品，却尚无能够展现长期尺度下历史土地覆盖变化的数据集。关注历史土地覆盖的用户群体包括气候建模学界、社会生态史学家以及地球系统科学家。欧洲是全球森林向农田土地转化历史最为悠久的大陆之一，因此解析该区域的土地覆盖变化具有全球重要意义。本研究将伪生物化方法（Pseudobiomization Method, PBM）应用于取自欧洲花粉数据库（European Pollen Database, EPD）的全欧982条花粉记录，以每200年为连续时间间隔，首次合成了距今9000年至今的泛欧洲土地覆盖变化序列。该方法将各采样点的花粉占比转换为8类土地覆盖类别（Land Cover Classes, LCCs），可直接与CORINE土地覆盖分类体系对标。各时间窗口内各类土地覆盖类别的占比，可为温带欧洲、北欧以及系列案例研究区域（法国西部、西阿尔卑斯山区、捷克与斯洛伐克）提供空间聚合后的土地覆盖变化记录。在欧洲尺度上，新石器时代农耕经济的影响可通过6000 BP起因人类伐林等土地利用活动导致的阔叶林减少得以观测。自4000 BP起，泛欧洲尺度的森林总占比已脱离此前的背景波动区间。2200 BP起，土地覆盖变化速率加快，到1000 BP时，前工业化欧洲的土地覆盖宏观格局已基本成型。明确欧洲人为土地覆盖变化的发生时间，将有助于深化对土地覆盖-气候相互作用机制以及现代人文景观起源的认知。