#Vers2022: 50-year resurvey data of French earthworm assemblages obtained after resampling Bouché's historical sites

Earthworms are key organisms in terrestrial ecosystems. They are found globally and provide significant ecological functions and ecosystem services, so their conservation should be a priority. Yet little is known about the large-scale impacts of global change on earthworm diversity, species distribution, and assemblage structure. More importantly, there are no comprehensive data on changes over long periods of time. In the 1960s, Marcel Bouché conducted a study by sampling earthworm assemblages in 1399 locations in mainland France, including the island of Corsica. Through the #Vers2022 project, we achieved the resampling of 418 of these historical sites, creating the first dataset to assess the long-term changes in earthworm assemblages at a large scale. This dataset includes Bouché (1972) assemblage data, with original taxon's names, absence data, and site descriptions, published in 1972 in French, which were still not freely accessible in a standardized, computerized format. It consists of 36,079 individual earthworm records from 1399 sites, documenting 127 species and subspecies between 1961 and 1970. Additionally, it provides the results of the #Vers2022 resurvey, which includes 11,137 individual records (22,344 including unidentified) from 418 resampled sites, documenting 122 species and subspecies between 2019 and 2023. We followed the framework of quasi-permanent plots, ensuring that the environment was as similar as possible between the historical sampling and its current resampling. These sites were sampled using a standardized, reproducible, and quantitative protocol, unlike the historical sampling, which was qualitative. The dataset also includes information on the individual body mass of each specimen, the total earthworm biomass of each assemblage, and soil analysis data. Furthermore, this work presents the updated taxonomy of each taxon provided by Bouché, along with an assessment of each species name in view of current taxonomy, as well as proposed names for future studies utilizing these data. The #Vers2022 dataset represents a significant improvement in our understanding of French earthworm diversity and can be used to assess changes in diversity and assemblages over a span of more than 50 years, including patterns in individual body mass. The data are released under a CC-BY-NC-SA license.