Ad hoc checklist of alien species in Belgium

Study Extent

The TrIAS project (Tracking Invasive Alien Species, http://trias-project.be) creates a unified and reproducible checklist of alien species in Belgium from published authoritative species checklists. This ad hoc checklist was created to account for gaps in the alien species coverage in those checklists and mainly includes taxonomic groups and newly introduced species not covered elsewhere (yet).

Sampling

Data for this checklist are compiled by directly contacting specialists of underrepresented taxonomic groups and scanning online databases and published but unstandardized species checklists for alien species in Belgium. The dataset also includes information previously gathered for the state of biodiversity in Flanders (incl. De Bruyn 2005, De Bruyn et al. 2007, Dumortier et al. 2007 & 2008, Adriaens et al. 2010, Demolder et al. 2017). The checklist is managed in a Google Spreadsheet (https://docs.google.com/spreadsheets/d/1LeXXbry2ArK2rngsmFjz_xErwE1KwQ8ujtvHNmTVA6E/edit?usp=sharing) where we aim to collect to following information: for taxa: scientific name, higher classification, taxon rank, and nomenclatural code; for distributions: location, country (BE), occurrence status, first and last observation date, and degree of establishment; for species properties: native range, (standardized) introduction pathway and realm (terrestrial, marine, freshwater); and the source on which this information is based. Data are added and verified by different people.

Quality Control

See step description.

Method steps

1. The source data for this standardized checklist is a Google Spreadsheet, maintained by the Research Institute of Nature and Forest (INBO) and updated regularly at https://docs.google.com/spreadsheets/d/1LeXXbry2ArK2rngsmFjz_xErwE1KwQ8ujtvHNmTVA6E/edit?usp=sharing.
2. We developed a RMarkdown script to document and perform the transformation of the data to Darwin Core, which includes the following steps:
3. Download the source data as a csv file that is versioned on a GitHub repository (https://github.com/trias-project/ad-hoc-checklist). See https://trias-project.github.io/ad-hoc-checklist for an introduction to this repository and the mapping of this dataset.
4. Perform some basic data cleaning of the raw data.
5. Generate stable and unique identifiers for each taxon (taxonID).
6. Create a taxon core file (http://rs.gbif.org/core/dwc_taxon.xml), with information about the higher classification.
7. Create a literature references extension file (http://rs.gbif.org/extension/gbif/1.0/references.xml), with information about the consulted literature for each taxon.
8. Create a distribution extension file (http://rs.gbif.org/extension/gbif/1.0/distribution.xml), including the cleaning of date information.
9. Create a species profile extension file (http://rs.gbif.org/extension/gbif/1.0/speciesprofile.xml), with coarse habitat information.
10. Create a description extension file (http://rs.gbif.org/extension/gbif/1.0/description.xml), with standardized pathway of introduction (using the pathway vocabulary from the Convention on Biological Diversity (2014)), native range (using the WGSRPD vocabulary from Brummitt (2001) where applicable), and invasion stage (based on Blackburn et al. (2011)).
11. The resulting Darwin Core data files are uploaded to the INBO IPT and documented with metadata.
12. The dataset is published and registered with GBIF.

This checklist includes over 250 alien species from 4 kingdoms. Arthropods constitute the largest proportion of taxa, followed by spiders and mammals.

1. Plantae
   rank: kingdom
2. Animalia
   rank: kingdom
3. Fungi
   rank: kingdom
4. Chromista
   rank: kingdom
5. Annelida
   rank: phylum
6. Arthropoda
   rank: phylum
7. Ascomycota
   rank: phylum
8. Basidiomycota
   rank: phylum
9. Bryophyta
   rank: phylum
10. Bryozoa
    rank: phylum
11. Charophyta
    rank: phylum
12. Chordata
    rank: phylum
13. Chytridiomycota
    rank: phylum
14. Embryophyta
    rank: phylum
15. Heterokontophyta
    rank: phylum
16. Mollusca
    rank: phylum
17. Nematoda
    rank: phylum
18. Platyhelminthes
    rank: phylum

This checklist covers species that are non-native in Belgium. The aim of the checklist is to provide information on species that are not (yet) covered by other checklists, so it is not meant to be comprehensive. For some taxa, information is included on its presence in Flanders, Wallonia and the Brussels Capital Region (the three main political regions in Belgium).