Studies on epiphytic bryophyte species richness and diversity in various urban-use complexes in Wroclaw (excluding urban forests) were conducted in 2013-2016 to check the research hypothesis that, in spite of the observed phenomenon of return of bryophytic epiphytes to cities, urban parks still favor species richness and the diversity of bryophytic epiphytes in built-up areas. Epiphytes (38 species) were recorded in all distinguished urban-use complexes but with strongly differentiated frequency, and 64% of all the trees colonized with epiphytes were situated either along streets or inside urban green areas (32% in each). It was shown that the highest species richness (89% of all the species found), bryophyte total coverage and values of the diversity indices referred to the latter complex. 20 species revealed preferences to occur mostly or exclusively on trees situated in urban parks. The second urban-use complex, which visibly affected the distribution of epiphytes, was the complex of streets; Tortula muralis occurred only on trees along streets and six other species occurred more frequently in these complexes than in others: Orthotrichum diaphanum, O. pumilum, O. pallens, Ceratodon purpureus, Syntrichia virescens, Bryum argenteum. In general, epiphytes – which were recorded on more than 20 trees – colonized a large number of phorophytes, from 12 to 33. They also showed some tendencies to occupy trunks of some host tree species more frequently than others. Detailed data are provided.
Bryo-floristic data from the 19th century and the first decade of the 21th century were compiled and compared to find trends in moss flora transformations during the analysed period. The total number of moss species reported from the glacial cirques in the Polish part of the Karkonosze Mts. amounted to 229 (230 taxa) and the comparison showed 49% of species replaced; 68 taxa were not refound and 45 were reported for the first time. But it seems highly probable that a great number of “newcomers” occurred only in the past and were omitted or overlooked by the 19th century researchers. 23 species among those persistent during the 20th century were found presently in no more than half of the previous localities, so they seem to demand care as probably threatened. Full list of taxa recorded from the individual objects in the studied period, including results of herbarium specimen revision, is provided.
Data documenting the occurrence of epiphytic bryophytes in the urban forests of the Wroclaw city were collected and reported for the first time. Research was carried out in 2015-2016, in forest areas situated within the city administrative boundaries, to find whether some epiphytic species reported from the Wroclaw environs in the 19th century and presently considered to be primeval forest relicts occur in urban forests. The survey was carried out using the established network of 50 study plots randomly scattered within the urban forested areas. In total 42 species (4 liverworts and 38 mosses) were recorded on 467 trees; three of them are primeval forest relicts. In this paper, the host-tree preferences, distribution in the individual forests, relative frequency, abundance and exposure to compass directions of the studied taxa are analysed. Of the species described, only 17 are obligatory epiphytes, while 22 of them are character forest species. However, 82% of the latter were noted on a small number of tree trunks. Two moss taxa, Hypnum cupressiforme and Platygyrium repens, were most frequently found (on 76 and 50% of the trees, respectively). Among the species recorded in the studied area, there are five that have been showing some expansive tendencies in Europe in recent decades. The potential ability of these species to spread in urban areas is discussed in relation to their general ecological requirements.
Changes in the vegetation of "Wrzosiec" mire in 1991-2009 (Western Pomerania)
Changes in the vegetation of a mire developing in forest lake hinterland in 1991-2009 are analysed and documented three times by phytosociological method. Within peat bog "islands", situated in the southern part of the lake, the most visible change is the development of a sparse pine-stand and thick shrubs of Salix species, Frangula alnus as well as increase in the participation of Molinia caerulea and some species of Scheuzerio-Caricetea class (Calamagrostis neglecta, Carex lasiocarpa and Sphagnum fallax). Vegetation of the lag zone shows fluctuating changes in the composition of plant communities depending on the water level that periodically changes. In the north-eastern part of the lake, a consistent slow process of terrestrialization was recognised.