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Water contraction drives stronger the formation of diatom assemblages in stream than human induced microhabitat-variability
211-228Views:282Today, climate change, together with other anthropogenic influences is considered as a major threat affecting aquatic ecosystems in several ways. Here, altering water contraction (standing and flowing phases) and human-induced habitat variability (natural and artificial stream sections) were studied as modifying factors driving community changes in benthic diatom assemblages of a Hungarian small lowland stream (Létai-ér). We assumed notable compositional differences between phases and habitats, but we expected these differences to decrease with drying. Moreover, lower diversity was hypothesized in assemblages of both artificial section and flowing phase. While taxonomic composition did not reveal significant differences between the sections, well pronounced compositional changes were found between phases. Surprisingly, no significant diversity changes were observed during water contraction. Compared to the natural microhabitat, however, artificial stream section was found to maintain more diverse diatom community. These results emphasize that modification effects of climate change induced hydrological extremes can lead to remarkable compositional changes in benthic algal assemblages even on a short time scale, that must be taken into account in both water management and nature conservation strategies.
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New species and changes in the bryophyte flora of the Mecsek valleys (Hungary)
157–176Views:123The paper discusses the bryophyte flora of 77 sites in the Mecsek Mountains, mainly in deeper valleys. It includes species that are new to the area’s flora and/or endangered in Hungary, as well as mosses that have become more widespread or locally abundant compared to data from 1968 and 1983. The names of the locations, their geographical centers (centroids), and the grid unit IDs of the Hungarian Flora Mapping Programme (HFMP), where the sites are located, are listed and referenced according to their number in the list. Some of the species are national rarities, such as Scleropodium touretii, newly recorded in the Mecsek in 2023. Its second known occurrence in Hungary is reported in the Enumeration. We detail the occurrences of several species new to South Transdanubia, including Dicranum spurium, Diplophyllum albicans, Hypnum jutlandicum, Isothecium myosuroides, Kindbergia praelonga, Rhynchostegiella curviseta, Riccardia palmata, and Sciuro-hypnum plumosum. Additionally, species newly recorded from the Mecsek Mountains include Fontinalis antipyretica, Leptodon smithii, Plagiomnium ellipticum, Pseudocampylium radicale, and Tortula brevissima. For two taxa, we present data of importance not only for the Mecsek, but also for the North-Hungarian Mts: Riccardia palmata, new for the Tornai-karszt, and Dicranum spurium, for which we confirm a very old record in the Zemplén Mts. We also note the widespread, sometimes massive occurrence of some aquatic and subaquatic mosses, e.g. Rhynchostegiella teneriffae, Hygrohypnum luridum, which have been recorded only once in the mountains in the last 50 years. The taxonomically uncertain Hygroamblystegium fluviatile with similar habitat requirements can now be found widely throughout the mountains. New populations of Palustriella commutata, considered endangered and declining in the country, have been found in the Mecsek. The expansion of (sub-)aquatic species is particularly surprising in the light of recent hydroecological studies indicating that the streams in the Mecsek are drying up. The situation is similar regarding Rhynchostegium rotundifolium, previously thought to be a Tilio-Acerion (slope and ravine forest) species, which is legally protected in Hungary and only had one record from the Mecsek in the last century. This forest species is now found in peri-urban, sub-urban, slightly to moderately disturbed and secondary habitats throughout the mountains. Similar to its preference in Germany, outside of semi-natural habitats it occurs mainly on built structures in forest edges, ruins, abandoned mine sites, often in stands mixed with black locust and contaminated with litter. Microeurhynchium pumilum, which prefers sub-Mediterranean and sub-Atlantic climate, shady and humid habitats, has become one of the most widespread and abundant forest bryophytes in the Mecsek, in contrast to its few records 60 years ago. Half (50%) of the new mosses in the flora of the Mecsek can be connected to the cooler boreal biome, while 21% is associated with the milder Mediterranean-Atlantic biome. The average of MAT (mean annual daily mean air temperatures averaged over one year) and MAP (accumulated precipitation amount over one year) of the 14 new species according to BET (Bryophytes of Europe Traits) indicates areas with much lower temperatures (7.7°C) than in Hungary, but with precipitation conditions (749 mm) similar to those in the Mecsek. The vast majority of the new species are extremely rare in Hungary, and are inconsistent with current climate warming trends. In contrast to the mosses with striking increase in records, the detection of new species is likely due to chance, in addition to systematic research at finer spatial scales, rather than to local expansion of the species. However, in the case of expanding and abundant species, it is still an open question whether their dynamics compared to 40-60 year old references are apparent or real: the result of sampling bias in previous surveys or a consequence of climate change. In any case, the abundance of the above mentioned bryophytes in the Mecsek is not consistent with their current Hungarian Red List threat classification, and this cannot be attributed to changes in definitions since 2010. The detected distribution and abundance, as well as the increase in the number of new species in the country within a decade, highlights the need for an updated Red List of Hungarian bryophytes.
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Data on the pioneer vegetation of the Lake Velence
203–208Views:332Lake Velence is one of Hungary's largest saline lakes. Part of its natural dynamics is that certain parts of the lake bed regularly dry out, providing pioneer surfaces suitable for the emergence of plants of the mudflats and drying (saline) ponds. During the particularly dry year of 2022, the water level was permanently and significantly low, allowing to study the vegetation of the dry lake bed. In the first half of the last century, the natural vegetation of the lakeshore (including salt steppes) was studied, but there are very few records of the pioneer species of the lake bed. The salt steppes around the lake have now largely declined, but due to low water levels, some of their characteristic species are still present in the lake bed (though, usually in low number of individuals). Examples include Crypsis aculeata, Cyperus pannonicus, Suaeda pannonica, the once abundant Suaeda prostrata, and the previously rare Crypsis schoenoides and Spergularia salina. Spergularia maritima was once widespread but currently not found in the lake bed. Although, Schoenoplectus litoralis is not a member of the ephemeral vegetation, but is a characteristic plant of the littoral zone of Lake Velence. This species probably appeared therein the middle of the last century and is currently spreading.
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Fern (Pteridopsida) flora of South Nyírség (East Hungary)
162–182Views:479The study presents a number of new data on the fern flora of South Nyírség, and reviews all available literature and herbarium fern records from the area. A total of 19 Pteridopsida species were detected in the region. The hart's tongue fern (Asplenium scolopendrium) and the soft shield fern (Polystichum setiferum) were hitherto unknown in the whole Nyírség region (flora district “Nyírségense”). The broad buckler-fern (Dryopteris dilatata), scaly male fern (Dryopteris affinis) and floating fern (Salvinia natans) are new records to the area of South Nyírség. Dryopteris dilatata has been found in a surprisingly great number of localities. Some morphological characters facilitating identification of this species are also discussed. The local pine plantations, fens, carrs and humid deciduous forests are important habitats for ferns. In some localities the co-occurrence of 5-6 fern species were observed. The increasing aridity in the last decade is posing a serious threat to ferns in the area.