Challenges and limitations of modelling historical spatial data on nature: 19th century flora and fauna of Peloponnese, Greece

Abstract. The aim of the study is the consolidation of a methodology suitable for organizing, utilizing and visualizing information regarding species distribution provided as text in historical sources. The work of the French Scientific Expedition in 1829 in Peloponnese, Greece, was used as a case study. We propose a system organized in three geographical levels: for information referring to a certain locality the form of a grid is appropriate, otherwise polygons depicting historical administrative areas or the whole region of Peloponnese should be preferred. There are three important caveats to avoid. First, species presence referring to an administrative area or region does not equal with presence in every locality and should not be transferred to the level of grid mapping, respectively reference of presence in the region should not be transferred to the administrative units’ level. Second, historical sources refer to species names that often are no longer valid; this kind of data must be referred to currently valid species names. Third, absence of reference of species presence should not be misinterpreted as absence of the species.