Effects of climate and land-use change on retention of semi-natural grassland plant species : A landscape study in southern and central Sweden

Abstract: Plants associated with the historical agricultural landscape are threatened. Land-use changes causing loss, fragmentation and degradation of semi-natural grassland habitats have resulted in many species becoming Red Listed. In addition, climate change favours generalist species, which risk outcompeting the specialist semi-natural grassland species. Conservation of small remnants of historical meadows and pastures left in landscapes has, on the other hand, proved to be of great importance for conservation of these species. A better understanding of how thespecies are affected by climate and land-use changes is essential for long-term and effective conservation plans and restoration measures. With this large-scale study, covering the whole of southern and central Sweden (ca 210000 km2), I investigated spatial variations in the number of retained semi-natural grassland species, and whether the proportion of retained distribution varies between species in different Red-List categories. Recently digitized data on the historical distribution of Swedish vascular plants made it possible to compare the historical and contemporary distributions of species on a large scale. Historical and current data of species distribution, climate and land use, and the presence of valuable grasslands were used to investigate the effects of changes in land use and climate on the species. Over 200 semi-natural grassland species were included in the analysis. The results showed that 34% of the seminatural grassland species in the study were Red Listed. There were spatial variations in retained distribution of species and the proportion of retained distribution varied between different Red-List categories. Species in the most critical category, CR had the lowestproportion retained distribution (median=0.39) and not Red Listed species the highest (median=0.95). The proportion of valuable semi-natural grasslands had a positive effect on retained distribution of species, while retention of open habitats had a negative effect, the lattercontradicting previous studies. Retention of species turned out not to be affected by climate change, which previous studies have suggested, but it was positively affected by a historically colder climate. The results of the study show the importance of preserving and restoring seminatural grasslands to reduce negative effects from other influencing factors, and that spatial differences in the effects are important to consider. The study underscores the need for more knowledge to understand the full impact of the threats that land-use change and climate change pose to these species.