A list of newly (re)appearing alien species in Belgium in support of decision making

Context Invasive alien species are an important driver of biodiversity loss. Policy responses are developed to address this threat and need to be based on the best available data, including information from alien species registries and occurrence data. The Tracking Invasive Alien Species (TrIAS) project implemented a workflow based on FAIR principles to identify new species in Belgium. These are species that have been newly observed on the territory or that were newly added to a species registry or checklist. The workflow is built on the Global Biodiversity Information Facility (GBIF) and uses the Belgian Global Register of Introduced and Invasive Species (GRIIS Belgium) as a baseline for comparison.  Description This dataset contains the outputs of the pipeline that generates a list of new alien species occurring in Belgium. This pipeline retrieves alien taxa from openly published species checklists or occurrence datasets on GBIF and compares this list with the Global Register of Introduced and Invasive Species - Belgium (GRIIS Belgium) which is published by the IUCN Invasive Species Specialist Group (ISSG). This register is based on the unified checklist of alien species in Belgium which was created by TrIAS in support of research and policy using an open and reproducible workflow. Appearing/reappearing species are defined as follows: Appearing: an alien species which newly occurs on the Belgian territory in the three years before the year of the GBIF download used for creating the occurrence cube for non-native taxa in Belgium. We will refer to this 3 years period as evaluation period. Re-appearing: an alien species reappearing on the Belgian territory after a latency of 4 years or more. For example, we consider a taxon reappearing in 2022 if observations occur in 2022 and 2018 or before. Files appearing_taxa.tsv reappearing_taxa.tsv Field values Field values of appearing_taxa.csv:  taxonKey: GBIF taxonKey canonicalName: scientific species name year: year of appearance ncells_prot_areas: number of 1x1km grid cells in protected areas ncells_BE: number of 1x1km grid cells in Belgium in_prot_areas: species occurs for the first time in protected areas of NATURA2000 in Belgium during the evaluation period (TRUE/FALSE) in_BE: species occurs for the first time in Belgium during the evaluation period(TRUE/FALSE) class kingdom classKey kingdomKey Field values of reappearing_taxa.csv:  taxonKey: GBIF taxonKey canonicalName: scientific species name year: year of reappearance ncells_prot_areas: number of 1x1km grid cells in protected areas ncells_BE: number of 1x1km grid cells in Belgium in_prot_areas: species reappears in protected areas of NATURA2000 in Belgium (TRUE/FALSE) in_BE: species reappears in Belgium during the evaluation period (TRUE/FALSE) n_latent_years: latency, in year, i.e. the number of years since last occurrence in Belgium class kingdom classKey kingdomKey Potential uses of the dataset The list of newly (re)appearing alien species in Belgium can be used for various purposes: to update the Belgian GRIIS checklist to flag the occurrence of new, regulated species on the territory (early warning) to develop a rapid response  to select species for quick impact assessment to select species for risk assessment to draft alert lists for horizon scanning alien species to select species for risk assessment to identify new introduction patways ...