International audienceno abstrac

New distribution data for 171 bryophyte taxa in the Roztocze National Park are provided. Among them there are 43 species protected by law in Poland, including 20 strictly protected species, as well as 13 species threatened in Poland. The research revealed 36 species (5 liverworts and 31 mosses) new for the region. Noteworthy is the occurrence of 19 mountain species and 10 bryophytes thought to be relicts of old-growth forests what confirms the specificity of nature of the Roztocze region. The most valuable and interesting finds are: mosses Campylophyllopsis sommerfeltii (Myrin) Ochyra, Dicranum viride (Sull. & Lesq.) Lindb., Buxbaumia viridis (Moug. ex Lam. & DC.) Brid. ex Moug. & Nestl. as well as liverworts Calypogeia suecica (Arnell et J. Perss.) Müll. Frib. and Cephalozia catenulata (Huebener) Lindb. A brief characterisations of these species are presented.

The study was conducted in an old, historical park, in the northern part of Stalowa Wola city (south-eastern Poland). The aim of the study was to investigate the diversity of moss-inhabiting diatoms of the white poplar (Populus alba L.) bark. During the study, a total of 47 diatom taxa were found, three out of which were considered as dominant. Three other species are mentioned in the Red List of the Algae in Poland: Achnanthes coarctata (Brébisson) Grunow, Luticola acidoclinata Lange-Bertalot and Stauroneis thermicola (Petersen) Lund.

Information on distribution and habitats of 176 bryophyte species revealed by a survey of the Wolin Island conducted during the 12 th Bryological Workshop organised by the Bryological Section of the Polish Botanical Society is presented. The most interesting (rare, protected and threatened

The grey heron (<em>Ardea cinerea</em>) is a good example of an engineering species that forms nesting colonies (called heronries) composed of up to a few hundred nests during the breeding season. It exerts strong pressure on surrounding vegetation, mainly because of the heavy input of organic matter and high eutrophication. The birds also alter light conditions through direct tree damage. We aimed to examine the influence of a grey heron breeding colony on the soil properties and functional composition of the herb layer in two different forest communities: a suboceanic pine forest and a riparian mixed forest. We also wanted to establish whether these changes would make the forest ecosystem more vulnerable to colonization by nonforest species with higher light and trophic demands. Small-seeded, light demanding eutrophic species showed a tendency to be more abundant under the nests in both forest types. The calculated odds ratio (OR) showed that the probability of the presence of nonforest species under the nests was 29.5 times higher than that in the control plots (56 plants species were analyzed). Additionally, the nonforest species appeared to have high light and trophic demand (OR of 12.3 for light demand; OR of 7.0 for trophic demand), which explains the species turnover observed in the bird-affected microhabitats.