The limitations, biases and uncertainties associated with digitally available information often limit the utility of occurrence records to properly describe the species’ realised bioclimatic niche. Here we assess changes in the perception of the realised niche of terrestrial vascular plant species after applying filters based on the geographical location of records according to their biogeographical status (native or introduced range), and range outliers documented by Plants of the World Online. We used Principal Component Analyses to describe the realised bioclimatic niches of 156,500 species. Our results show that restricting the available occurrence records to the delimited geographical distributions results in a distortion of the representation of these niches. The bioclimatic niche can be reduced by more than half of the environmental volume occupied when we filter out species records based on expert map distributions. Between 20-40% of the species in each order presented decreases in their observed realised niche after discarding records outside of their recognised range of distribution. Strikingly, this percentage raised up to 68% in Osmundales and Pinales or 83% in Equisetales. Most of the species evaluated (96%) only presented data in native ranges, but c. 90% of the species with introduced ranges expanded their realised niche in the invaded areas, evidencing that biological invasions often occur outside of the native climatic conditions. This calls for caution when selecting occurrence records from public repositories to conduct massive analyses using all available information on terrestrial plants. Validating discrepancies in niche estimations derived from the curation process will allow drawing robust conclusions about species’ responses to environmental changes.

Beta diversity patterns are essential for understanding how biological communities are structured. Geographical and environmental factors, as well as species dispersal ability, are important drivers of beta diversity, but their relative importance may vary across spatial scales. In this study, we evaluate whether beta diversity changes across geographical scales and analyse how different drivers affect turnover patterns of native seed plants in an oceanic archipelago, the Azores (Portugal). Using a 500 x 500 m resolution grid, we selected cells that are covered by one of the following habitats: native forest, naturalized vegetation and seminatural pastures. We calculated species turnover at three spatial scales: i) between islands, ii) between cells within each island, and finally iii) between cells of each of the habitats of interest in each island. We then calculated the contribution of dispersal syndromes (endozoochory, epizoochory, hydrochory and anemochory) to turnover at each of the scales. Lastly, we assessed the relationship between geographical and climatic distances and habitat composition with turnover. Turnover was higher at the smallest scale, particularly in seminatural pastures, and decreased with increasing spatial scales, a pattern potentially associated with the historical fragmentation and current patchy distribution of native forest and seminatural habitats in the Azores. Dispersal syndromes and habitat composition had a negligible effect on turnover at all scales. Geographical distance had a positive effect on turnover at all scales, increasing with scale. The relationship between turnover and climatic distance was only significant at the intermediate and small scales in specific islands and habitats. Scale plays an important role at determining the effect of the drivers of turnover, in particular geographical and climatic distance. These results highlight the need to carefully select the scale of analysis when studying turnover patterns, as well as identifying the potential drivers associated with each scale.