Species richness and range restricted species of liverworts in Europe and Macaronesia
Species richness and range size patterns of European liverworts are analyzed at global scale. At the scale used in the study, species richness decrease from west to east and from the boreal areas towards both south and north. There is a trend that the larger the areas are the more species there are, but this trend is weak and cannot explain much of the patterns. Of the 490 liverwort species occurring in Europe and Macaronesia, 14.5 % have very small distribution ranges (as defined here; H’<1), which is a much lower figure than e.g. Malesia where over 50 % has small distribution ranges. Number of range restricted and very range restricted species is correlated exponentially with number of species. The geographic patterns of species richness and range restriction are not the same as for vascular plants. The more range restricted a liverwort species is in Europe the more it tends to be an oceanic species. Great Britain and France have most range restricted species but Portugal and the Macaronesian Islands have a larger proportion of liverwort species with small distribution ranges. However, the calculated rarity index is low compared with e.g. Malesia due to both lower number of species and lower proportion of range restricted species.