A GIS-based policy support tool to determine national responsibilities and priorities for biodiversity conservation

concern and administrative units [36, 37]. What is important is that an area can be clearly delineated as a polygon for the unit of concern (distribution area), based on available data. Examples of sources include the webservices of IUCN (https://www.iucnredlist.org/) and Map of Life (https://www.mol.org) [52]. The distribution of each species or habitat category must be available as a separate layer for use in our tool. Files downloaded from the IUCN webserver require additional processing so that data for each species is separated into a unique shapefile, and renamed by adding the prescript “s-” (following the naming convention described in more detail in the section “Technical requirements”). These shapefiles must be accompanied by an ASCII text file that contains the species names separated by semicolons (see S3 File for example). Focal area and reference area. The focal area is the geographical area for which conserva- tion priorities are determined. For national responsibility assessments, the borders of an administrative unit, such as a country or province, should be used to demarcate the focal area. The focal area must be completely enclosed by the reference area. The reference area defines the extent and serves as a reference to determine whether the focal area contains a higher percentage of the distribution range than expected by the size of the focal area. The selection of the reference area will depend on the goal of the assessment. If the goal is to define priorities for a particular geographic region, the reference area should be

the combined spatial extent of all biogeographical units in which at least one of the assessed species occurs. If the goal is to determine the national responsibility of a lower-level adminis- trative unit, such as a province, then the reference area can be a higher-level administrative unit, such as a country. Results are comparable only within the same assessment. All three layers described above (reference area, biogeographical unit, focal area) should contain at least one polygon. Each polygon should relate to and be sufficiently described by Fig 4. Decision tree for identifying national responsibilities in species conservation after [36] (modified). Step one is to select the taxonomic unit. Step two is to determine the distribution pattern of the species: “local” defines a species with a patchy distribution within one biogeographic region (in the case of Europe, sensu European Habitats Directive, Council Directive 92/43/EEC), and “wide” refers to a species distribution spanning more than one biogeographic region. The third category is “regional”, wherein two-thirds of the distribution area of a species is located in one biogeographic region. Examples can be found in [37]. The final step is to calculate the proportional distribution of a species in the focal area. Two proportions are calculated–the expected distribution proportion (DPexp) and the observed distribution proportion (DPobs). https://doi.org/10.1371/journal.pone.0243135.g004 PLOS ONE GIS-based policy support tool to determine national responsibilities for biodiversity conservation

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