Open Access

Orange lily Lilium bulbiferum subsp. bulbiferum occurs in the mountains of Western and Central Europe. Within almost the entire area of distribution, it is considered to be rare and endangered. The main purpose of the present study is to analyse the variability of environmental conditions of sites of the orange lily that are considered natural on its north-eastern border of occurrence. Using vegetation databases from Poland, the Czech Republic and Slovakia and our material collected during field work in the Western Carpathians and the Sudetes, we analysed the variability of species composition within communities with the occurrence of L. bulbiferum subsp. bulbiferum. The classification was performed using a modified TWINSPAN algorithm in the JUICE software. Ecological analysis was performed on the basis of Ellenberg indicator values with a Zelený-Schaffers modified permutation test. In general, the findings indicate that in the study area there are at least seven plant communities, within three separate classes, with the occurrence of the orange lily. All vegetation units distinguished here are semi-natural communities, which are maintained through extensive and traditional agricultural practices. Microclimatic conditions, which indicate a narrow ecological tolerance of the species to light availability and temperature, may have a crucial effect on the distribution of L. bulbiferum subsp. bulbiferum on the north-eastern border of its range in Europe. These factors significantly reduce the possibility of penetration of the species into forest or scrub communities. On the other hand, owing to far wider ranges of tolerance to moisture conditions and soil reaction than previously considered typical of the species, the orange lily can occur in different light-demanding communities, from acidic pastures up to calcareous thermophilous grasslands. An almost exclusive presence of L. bulbiferum subsp. bulbiferum in semi-natural habitats suggests that active management and protection are crucial to protect its full genetic variation on the European continent.