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Specific variability and ecological meaning of seed weights
295-330Views:186There is an almost twelve order of magnitude difference in the seed weight of recent plant species. Studying the causes, patterns and consequences of this high variability is a crucial issue in plant ecology. In this paper we summarise the main conclusions of the studies in this topic to get a broad and general view of the possible explanations of high variability in seed weights and its consequences on dispersal, seed predation, seed bank formation, germination, establishment and plant growth, and on the structure and function of plant communities. Because of the extremely high number of papers published in this topic, we aimed at to concentrate on papers published in highranked international journals in the last few decades, having a special focus on publications from the Carpathian Basin. It was found that growth form, body size, genom size, latitude and light availability are responsible for the detected high variability in the seed weights of species. Infra-individual variability is mostly caused by the effects of the position on the maternal plant and the seed size – seed number trade-off. The effect of dispersal by wind or by seed predators on the variability of seed weights and its ecological consequences are the most studied. Predicting persistence on the basis of seed size and seed shape also has been a popular research topic lately. Studying the effects of seed weight variability on the structure of plant communities is also becoming more and more important, but no general conclusions could be drawn yet.
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The role of soil seed bank in restoration and dynamics of Hungarian plant communities
116-135Views:133Soil seed bank has an important role in maintaining plant populations and communities, in regeneration processes, and also provides information about the history of the studied site, the past land use practices, the biotic and abiotic changes and about the current degradation degree. In Hungary there are many researchers related to the seed bank, but from the last few years we do not have a comprehensive work about the results of these works. My goal is to report on the results of former seed bank researches in Hungary and also to highlight the missing topics and further research opportunities. The review is based on 49 articles, the oldest one dates back to 1922, the newest one was published in 2015. Most of the studies use greenhouse or laboratory germination tests to determine the viability of seeds. The earliest studies, which examined the weed seed bank of farmland soils found, that the seed bank was much higher than the total seed bank found on natural and semi-natural habitats studied later. Researchers found the lowest seed bank density in forests. Disturbed sites and former agricultural sites had higher seed bank densities than sites without agricultural use. Most part of seed bank was located in the upper soil layer in all studied communities. In most studies usually a small similarity was detected between the composition of soil seed bank and aboveground vegetation, which suggests that the seed bank has a subordinate role in regeneration processes. Seed bank type classification is lacking from the three-quarter of Hungarian flora species, despite that it is essential for protecting species and communities and for developing proper protection against invasive and alien species.
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The degradation of hygrophilous plant associations of the Nyárjas Lake (E Hungary)
63–77Views:131The Nyárjas Lake (located near Kállósemjén, East Hungary) was one of the most typical bogs in the Nyírség until the early 1980’s. Most of its area was covered by the association of Carici-Menyanthetum. The number of species characteristic to the mentioned association was generally high. As the climate became drier, hotter and were characterised by higher magnitude of extremities, the water coverage became no longer as permanent. This resulted that the Menyanthes trifoliata and Listera ovata became extinct by 2000. Lemno-Potamea species were not found after 2010. Bidentetalia, Calystegietalia, Chenopodietea and Secalietea species became more prevalent, particularly in drier periods, and locations where Carici-Menyanthetum used to be characteristic. Cirsium arvense in the mid-1990’s and that of Urtica dioica in the mid-2010’s became dramatically abundant. Both the number and coverage of species indicating habitat degradation have increased. The composition of wet meadow plant associations shifted towards the drier Arrhenatheretea. A moderate revitalisation of wetland associations was, however, observed coinciding years with higher precipitation.
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Remnants of closed oak woods on loess in the Mezőföld (Pulmonario mollis-Quercetum roboris Kevey 2008)
66–93Views:185The phytosociological characterization of closed oak forests occurring in the loess-covered part of Central Hungary (Mezőföld) is presented. Such forest fragments are found very sporadically in that predominantly treeless region, mostly in semi-dry habitats of north-facing hillsides. This plant community represents an intermediate stage between open steppe woodland (Aceri tatarici-Quercetum pubescentis-roboris) and closed mesic oak-hornbeam forests (Corydali cavae-Carpinetum). Analyses of 20 phytosociological samples using multivariate grouping methods (cluster analysis, principal coordinates analysis) showed a clear difference between these samples and samples of similar communities occurring in the area. In the species composition the characteristic elements of dry and mesic oak forests (Quercetea pubescentis-petraeae, Quercetalia cerridis, Aceri tatarici-Quercion and Fagetalia, respectively) played a major role. On the other hand, dry grassland species (Festuco-Brometea, Festucetalia valesiacae, Festucion rupicolae, etc.) were much less significant than in steppe woodlands. In terms of chorology, European and sub-Mediterranean floristic elements were dominant in the samples, while the proportion of continental elements was substantially smaller than that in steppe woodlands. As a result, our samples were identified with the plant association Pulmonario mollis-Quercetum roboris Kevey 2008, which is classified into the suballiance Polygonato latifolio-Quercenion roboris Kevey 2008 in the phytosociological system.
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Rare vascular plants and fungi of Zalaegerszeg-Botfa (W Hungary)
95-103Views:205The present study reports the occurrence data of 3 macrofungi and 47 vascular plant taxa, collected in Zalaegerszeg-Botfa between 2006 and 2017. These new data provide valuable additional information to the distribution map of the studied species. The spatial and abundance information of both protected and non-protected species can contribute to the future biodiversity monitoring activities in order to asses and mitigate the human impact upon natural plant communities and semi-natural habitats.