Conservation status and ecology of the highly threatened endemic Gentianella bohemica

The Bohemian gentian (Gentianella bohemica) is a highly threatened endemic species of nutrient poor grasslands on the Bohemian Massif in Austria, Bavaria and the Czech Republic. Here, we analyse its microhabitat preferences and the role of historic and current land management and seasonal climatic variability in the changes in population sizes. A total of 114 populations of G. bohemica were recorded from 2003 onwards, of which only 50 were still extant in 2017. The highest number of flowering plants (29,200) was recorded in 2009 and the smallest in 2016 (4,084). Inter-annual population sizes fluctuated strongly and were partly synchronized with differences in the weather in preceding years, notably average temperature and precipitation in the growing season (May to August), i.e. wet and warm conditions in preceding years had a positive influence on population size. For analysing microhabitat preferences (using Ellenberg indicator values) and species of plants associated with G. bohemica, 122 plots (0.25m²) were established at 22 sites with G. bohemica, of which 45 were placed around a plant of this species, while 77 were randomly located where this species was absent. Gentianella bohemica preferred microhabitats characterized by nutrient poor vegetation and this preference was also indicated by several species that were highly over-represented in plots with G. bohemica. A high proportion of open soil in the plots also favoured the occurrence of G. bohemica, possibly because it facilitated seedling establishment. Data on land management from 2003 onwards revealed that dedicated conservation measures somewhat positively, but not significantly so, are associated with changes in the sizes of the populations of this species. The results of this study should improve conservation management and ensure the long-term survival of this highly threatened grassland specialist.