A grid-based map for the Biogeographical Regions of Europe

Abstract

Background: Biogeographical units are widely adopted in ecological research and nature conservation management, even though biogeographical regionalisation is still under scientific debate. The European Environment Agency provided an official map of the European Biogeographical Regions (EBRs), which contains the official boundaries used in the Habitats and Birds Directives. However, these boundaries bisect cells in the official EU 10 km × 10 km grid used for many purposes, including reporting species and habitat data, meaning that 6881 cells overlap two or more regions. Therefore, superimposing the EBRs vector map over the grid creates ambiguities in associating some cells with European Biogeographical Regions.

New information: To provide an operational tool to unambiguously define the boundaries of the eleven European Biogeographical Regions, we provide a specifically developed raster map of Grid-Based European Biogeographical Regions (GB-EBRs). In this new map, the borders of the EBRs are reshaped to coherently match the standard European 10 km × 10 km grid imposed for reporting tasks by Article 17 of the Habitats Directive and used for many other datasets. We assign each cell to the EBR with the largest area within the cell.

Keywords: biodiversity monitoring; biogeographical boundaries; biogeography; habitat; redefining; regionalisation..

Figure 1.

Map of the 11 European Biogeographical Regions (EBRs) showing the 7809 x 10 km × 10 km cells containing two or more EBR boundaries. These cells are displayed as empty quadrats with black borders, but given the scale, appear as black lines unless zoomed in. (The ‘outside data coverage’ is here added in grey to show the geographical boundaries with the EBRs).

Figure 2.

Grid-Based Map of the 11 European Biogeographical Regions (plus the ‘outside data coverage’ in grey) at 10 km × 10 km resolution (GB-EBR Map). This figure is provided only for the reader’s convenience. The raster file is available at the URL: https://zenodo.org/record/3760925#.XqBOKcgzZPY

Figure 3.

Conversion of the EBR boundaries from the EBRs (vector) to the GB-EBRs (raster) map in two different geographical zones. Top row: Pyrenees - (a) Vector boundaries of Alpine, Atlantic, Continental and Mediterranean biogeographical regions, (b) 10 km × 10 km cells that overlap two or more biogeographical regions, (c) comparison between the vector boundaries and the new grid-based ones in the GB-EBRs map. Bottom row: Caucasus - (d) Vector boundaries of Alpine, Anatolian, Steppic biogeographical regions plus ‘outside data coverage’, (e) 10 km × 10 km cells that overlap two or more biogeographical regions, (f) comparison between the vector boundaries and the new grid-based ones, reshaped in the GB-EBRs map.