Exploring biodiversity challenges in Europe: Completeness, geography and environmental representativeness

Biases and gaps in biodiversity data lead to significant disparities in knowledge among species descriptions and distributions of different taxonomic groups. These gaps could be addressed by utilizing predictive models, but this requires ensuring that available information is environmentally representative. In this study we utilize data from GBIF to investigate geographical biases, gaps and spatial completeness patterns concerning species distribution for the main classes of terrestrial organism in Europe. By identifying the spatial units with comprehensive inventories for each class, we offer insights into their quantity, distribution, and ability to capture the environmental variability of the European subcontinent. The results clearly demonstrate a high spatial heterogeneity and variability between taxa in the number of well-surveyed spatial units, showing that the units with high completeness for vertebrates and vascular plants are several times more numerous than those available for invertebrates and mosses. Regarding the environmental variability represented by the available data, results demonstrate the uncoordinated and contingent character of the accumulation process of biodiversity information and the need of an extra effort, which should be more intense in those taxa with a lower geographical coverage of their data. These challenges raise doubts about the reliability of these data in providing a comprehensive understanding of biodiversity distribution, as well as hindering model estimations. Extra compilation efforts should be mainly directed towards those spatial units capable of improving the current environmental representation of the spatial units considered well-surveyed, to reach a representative sample capable of producing effective interpolations and reliable predictions of species distributions.