The effect of land-use change on the distribution of Gentianella austriaca and G. praecox in Austria

Landscapes and their management in central Europe have dramatically changed during the last century, leading to an ongoing loss of biodiversity at all levels. To address the effect of these changes on the distribution of species and to better understand how changing proportions of different types of land-cover influence grassland taxa, we investigated the historical and present-day distribution of two Gentianella species (G. praecox, G. austriaca), considered to be indicators of oligotrophic grassland, in north-eastern Austria. The distribution data obtained from herbarium vouchers, literature and mapping projects was related to historical habitat data obtained from military maps dating back to the end of the 19th century and present-day data on habitat availability based on remote sensing methods. Areas of suitable and unsuitable habitats were obtained from historical and recent land-cover data for 133 sample plots of 78.5 h each, surrounding either extinct or extant Gentianella populations. Differences in percentages of habitat types between the extinct and the extant populations were investigated in the recent landscape data. Subsequently, the percentage changes between recent and historical landscape data were compared for extinct and extant populations. Results revealed regional and local hotspots of extinction and significant overall trends of gains in forest land-cover and losses in grassland and wetland land-cover, and deviating regional trends for arable field and settlement land-cover. There was a clear deteriorating effect of increased settlement and decreased wetland land-cover on the distribution of the species studied. Landscape heterogeneity indices, however, did not show significant differences between the extinct and extant populations sampled. Results are in line with well-documented trends in central Europe and indicate a need for rapid and effective conservation measures.