One of the habitat types protected within the framework of the NATURA 2000 network due to the presence of species of European importance are fresh meadows from the Arrhenatherion alliance. The maintenance of their characteristic floristic composition depends on habitat conditions and extensive use, while any changes in this respect trigger succession transformations potentially threatening their nature value. The aim of the study was to conduct nature and habitat valuation of one of the largest meadow complexes in the Wielkopolska region, i.e. Wielki Łęg Obrzański, which will make it possible to describe the preservation status of fresh meadows and their habitats. Based on multifaceted analyses of 535 relevés made using the Braun-Blanquet method in the years 2006–2012 and representing the Arrhenatherion alliance, the phytosociological and botanical structure as well as constancy of species in individual variants (floristic types) were determined. Moreover, their habitat conditions were defined, i.e. soil moisture and nitrogen content using the index method according to Ellenberg, while laboratory methods were used to determine the content of organic matter, soil moisture as well as the contents of potassium, magnesium and phosphorus in soil. Floristic composition of fresh meadows from the Arrhenatherion alliance differs due to high heterogeneity of habitat. The presence of fresh meadow phytocenoses both on dried organic soils (the driest forms of flood meadows) and on mineral soils (oak-hornbeam forests) contributes to differences in the floristic composition both in ryegrass meadows and grass–fescue meadows, mainly due to soil moisture and fertility as well as sward use type. This constituted the basis for the identification of lower syntaxonomic units in the internal structure of the plant associations. Five variants were distinguished in Arrhenatheretum elatioris, while the community of Poa pratensis–Festuca rubra was developed in as many as 8 variants.

Celem pracy było przedstawienie struktury fitosocjologicznej wybranych zbiorowisk trawiastych na płytkich glebach torfowych podlegających procesowi murszenia (humifikacji i mineralizacji torfu). Obszar badań zlokalizowany był pomiędzy północnym, środkowym i południowym kanałem rzeki Obry (Nizina Wielkopolska, centralna Polska). Badania glebowe przeprowadzono w maju i wrześniu 2022 roku, a badania fitosocjologiczne w maju i wrześniu 2022–2023 roku. Próbki gleby do analiz laboratoryjnych pobrano z najwyższych poziomów glebowych na głębokości 0–20 cm w 20 punktach badawczych. Wykonano 76 zdjęć fitosocjologicznych. Wyróżniono pięć jednostek syntaksonomicznych roślinności: Molinietum caeruleae, zbiorowisko z Poa pratensis-Festuca rubra, Arrhenatheretum elatioris, Lolio-Cynosuretum i Alopecuretum pratensis. Zbiorowiskiem o najwyższych wartościach wskaźnika różnorodności i liczbie gatunków odnotowanych w zdjęciach fitosocjologicznych było Molinietum caeruleae, podczas gdy najuboższym w gatunki z najniższym wskaźnikiem było Lolio-Cynosuretum. Gleby zostały sklasyfikowane jako Umbric Gleysols, Mollic/Umbric Gleysols, Histic Gleysols, Histic Gleysols (Murshic). Najwyższe zawartości TOC i TN odnotowano dla zbiorowiska Poa pratensis-Festuca rubra, a najniższą dla Arrhenatheretum elatioris. Wartości pH wskazywały na gleby lekko kwaśne w przypadku następujących zbiorowisk: Alopecuretum pratensis, Molinietum caeruleae, Lolio-Cynosuretum, zb. Poa pratensis-Festuca rubra oraz gleby lekko zasadowe w przypadku Arrhenatheretum elatioris. Wyniki analizy dyskryminacyjnej wykazały, że najważniejszym statystycznie istotnym czynnikiem różnicującym zbiorowiska roślinne było pH gleby mierzone zarówno w H2O, jak i w KCl. Zbiorowisko Molinietum caeruleae występowało na glebach ubogich w składniki mineralne o stosunkowo wysokim stosunku C:N. Wskaźnik różnorodności Shannona-Wienera był istotnie ujemnie skorelowany z TOC i TN. Wskazane jest dalsze utrzymywanie badanych stanowisk jako roślinności łąkowej. Zbiorowiska użytków zielonych mają szanse na przetrwanie w procesie murszenia, pod warunkiem prawidłowego użytkowania (regularnego koszenia lub wypasania i nawożenia) i regulacji stosunków wodnych. Użytki zielone, oprócz wzbogacania gleb w składniki pokarmowe, stwarzają najlepsze warunki do ograniczenia procesu rozkładu materii organicznej w poziomach akumulacyjnych i próchnicznych o charakterze murszowym, co jest niezwykle istotne w obliczu zmian klimatycznych.

The study presents the findings of research into the effect of the variability of site conditions on their floristic composition providinga basis for the identification of lower phytosociological units. Patches of Arrhenatheretum elatioris described with the assistance ofphytosociological surveys conducted using the Braun-Blanquet method were subjected to multi-criteria evaluation. On their basis, thefollowing parameters were determined: ecological and botanical structure, geographic-historical distribution, the structure of the lifegroupsof the floristic types identified, as well as natural values by the Oświt method and sward fodder value according to Filipek. In orderto determine the causes of the floristic variability observed, the following soil conditions were assessed: moisture content, soil reactionand nitrogen content by Ellenberg’s indicator method, as well as potassium, magnesium and phosphorus content by the appropriatelaboratory methods. Typical forms of Arrhenatheretum elatioris phytocenoses were found to develop on mucky soils in moderately moistsites. Patches of ryegrass occurring in sites with a periodically higher moisture content on organic soils refer to the Alopecuretum pratensisassociation. On the other hand, the sward of ryegrass meadows developed on dryer, mineral soils was characterised by increased numbersof species characteristic for xerothermic swards from the Festuco-Brometea class and sandy plant communities from the Koelerio glauca-Corynephoretea canescentis. More intensive utilization, primarily-fertilisation, was among the causes of the development of species-poorphytocenoses of low natural value but sward of a good fodder value.

Background/Objectives: Sosnowsky’s hogweed Heracleum sosnowskyi, which originated in the Greater Caucasus region and spread rapidly across Central and Eastern Europe after being introduced as cattle fodder in the 1950s, is an example of an extremely dangerous invasive species listed by the European Union. This study aimed to estimate the genetic diversity of 6 native populations of Sosnowsky’s hogweed from the Caucasus region of Russia and Georgia, as well as 15 invasive populations from Lithuania and Poland, and to assess the adaptability of hogweed in new environments. Methods: Genetic analyses of plant material were conducted, including DNA extraction, ISSR genotyping, PCR product separation, and subsequent molecular data mining and analysis. Results: A pairwise Mantel test revealed a positive correlation between geographical distance and the genetic diversity of the hogweed populations. The presence of three distinct allele pools was confirmed in the populations under study, with genotypes from Poland dominated by the first allele pool, which had the largest number of polymorphic and private loci. Analysis of molecular variance by origin showed that 99% of the variation was within the analysed hogweed populations, with only 1% being between them. Native populations from Russia were genetically distinct from those in Poland and Lithuania. Some of the Georgian population shows genetic similarities to Russians, while the rest shows similarities to the secondary invasive Lithuanians. Conclusions: Introduced populations of H. sosnowskyi are characterised by considerable genetic variation, likely resulting from multiple introductions and subsequent evolutionary processes, which may facilitate local adaptation and invasiveness, although overall large-scale genetic differentiation remains low.