Historical Floras: addressing their genesis in order to be viewed from a modern-day perspective. A case study from Northern Italy

Historical Floras are biodiversity-oriented textual sources, which refer to times when scientific methods were far different compared to the present. They are also geographical documents, as the entire work is referred to a focal region explored by certain collectors and following certain principles, since the taxa recorded are usually accompanied by a description of the locality of the observation. Retrospective georeferencing, as well as taxonomic revision, of the records in Historical Floras are, however, very challenging processes, which are usually not taken into account. As a result, very few global overviews of Historical Floras exist to date. In this article we present the analysis of the 7767 floristic records of the late XIX century Flora of the province of Bologna (N-Italy) compiled by Girolamo Cocconi. We processed these records by georeferencing them, whenever possible, to 659 pairs of coordinates and coupling them with the analysis of the collectors involved besides the author, as to provide the spatial and temporal dimension that permits us to further understand the taxonomic information given by the species listed. This allowed us to detect a bias in the exploration of the territory, which depended on accessibility and/or attractivity of the areas for fieldwork and shifted through time as function of the available collaborators who influenced the definition of the floristic pattern of the territory. Finally, we provided a diachronic analysis with the present flora to document the most significant land use changes based on selected floristic target groups.