Anna Monika Stefanowicz

Postępująca urbanizacja wiąże się z wieloma problemami. Miasta borykają się z efektem miejskiej wyspy ciepła, zaburzeniem stosunków wodnych, zanieczyszczeniami różnego typu, a także niedoborem terenów zielonych o wysokiej jakości biologicznej. Jednym z najbardziej charakterystycznych typów zieleni miejskiej są trawniki. Są one poddawane różnorodnym zabiegom, przede wszystkim koszeniu. Badania pokazują, że zmniejszenie częstotliwości koszenia i przekształcanie miejskich trawników w łąki prowadzi do znacznego wzrostu różnorodności roślin oraz liczby kwitnących kwiatów. Wiąże się to ze wzrostem liczebności i różnorodności bezkręgowców, przede wszystkim owadów, w tym wielu zapylaczy. Częstotliwość koszenia wpływa również na środowisko glebowe, między innymi mikroorganizmy i realizowane przez nie procesy, jednak efekty te są nadal słabo poznane. Ograniczenie intensywności koszenia może wpływać pozytywnie nie tylko na bioróżnorodność miejskich terenów, lecz również na komfort życia mieszkańców poprzez poprawę mikroklimatu, redukcję poziomu zanieczyszczeń oraz zwiększenie estetyki otoczenia.

Rosa rugosa Thunb. (Japanese Rose) is one of the most invasive species in Europe. It spreads spontaneously in coastal areas of western, central and northern Europe, posing a threat to dune habitats, including those indicated in the EU Habitats Directive as particularly valuable. R. rugosa has already been reported to displace native plants and alter soil properties. However, little is known about how these effects are mediated by the habitat context or the invader condition (health, ontogenetic stage). This study addressed that gap by examining vegetation and soil in 22 R. rugosa-invaded sites, half of which were in yellow dunes and the other half in grey dunes, i.e. two habitats representing the earlier and later stages of dune succession. The study was conducted on the Hel Peninsula (Poland’s Baltic coast). R. rugosa had a significant impact on dune vegetation, but the impact was strongly dependent on the habitat type. In the yellow dune sites, R. rugosa outcompeted most resident plant species, which translated into a strong decline in their total cover and richness. The invasion was almost not accompanied by changes in soil properties, suggesting that it affected the resident vegetation directly (through space takeover and shading). In the grey dunes, R. rugosa caused a shift in species composition, from that characteristic of open communities to that typical of forests. In this habitat, a significant increase in the soil organic layer thickness under R. rugosa was also observed, which means that both direct and indirect effects of the invasion on the vegetation should be assumed. Finally, a negative relationship was found between the total chlorophyll content in R. rugosa leaves and the parameters of resident plant communities, showing that the invasion effects can vary not only across habitats, but also with the condition of the invader. The results may have practical implications for managing R. rugosa invasions in coastal sand dune systems. Since R. rugosa accelerates grey dune succession, protecting this habitat may be more urgent and, at the same time, more complicated than protecting dunes at the earlier stages of development.

Purpose: Herbaceous plants are important components of temperate forest structure and its functioning, however, their impacts on arbuscular mycorrhizal fungi (AMF) remain largely unexplored. We studied the influence of forest herbaceous plant species on AMF abundance, morphospecies richness, and community composition in soil. Methods: We tested the influence of plant species identity in an outdoor mesocosm experiment, using two soils, differing in physicochemical properties, planted with four plant species of contrasting traits related to morphology, phenology, reproduction, and ecology; the hemicryptophyte, summer-green Aegopodium podagraria, and spring ephemeral geophytes comprising Allium ursinum, Anemone nemorosa, and Ficaria verna. The plants were grown on both soils in four monocultures, in a combination of A. podagraria and A. ursinum, and a mixture of all four species. Results: Aegopodium podagraria and A. ursinum promoted AMF abundance and diversity the most. Higher AMF root colonization and/or soil concentrations of AMF structural and storage markers 16:1ω5 PLFA and NLFA, as well as higher AMF spore and morphospecies numbers were found in the A. podagraria and A. ursinum monocultures and mixture. The short period of photosynthetic activity of A. ursinum due to rapid leaf decay does not negatively affect the symbiosis with AMF. Although A. nemorosa and F. verna are mycorrhizal, their effect on AMF in soil was weak. Conclusions: The plant impact on AMF may be related to the differences in plant coverage and the character of their interactions with AMF. The herbaceous plants can form niches in soil differing in AMF abundance and diversity.

This study aimed to determine the impact of invasive Rosa rugosa Thunb. on the plant communities of the Baltic coastal dunes. The study was carried out in 22 sites scattered along the Hel Peninsula (Poland). Each site consisted of a pair of plots: a plot with the invader vegetation and an adjacent plot with the resident vegetation (control plot). For each plot, botanical data (the abundance of individual species, total species richness and the richness of species belonging to different functional groups) were collected and basic soil parameters were measured. According to the analysis of the control plot species composition, the study sites can be divided into two groups, including the plant communities characteristic of the yellow dunes (Elymo-Ammophiletum arenariae association, EA; N = 11 sites) and those characteristic of the grey dunes (Helichryso-Jasionetum litoralis association, HJ; N = 11 sites). R. rugosa influenced these two communities differently. In the EA sites, it displaced many species, leading to a significant decrease in the species richness. In the HJ sites, it caused a shift in the species composition; although it outcompeted some species (e.g., zoochores), it also created conditions for the existence of others (e.g., graminoids, a plant group that, interestingly, was negatively affected by the invader in the EA sites). Changes in the plant communities probably resulted not only from the direct impacts of R. rugosa on the plants (by shading and occupying space) but also from invader-induced soil alternations (an increase in the organic layer thickness and an increase in pH and the content of some nutrients).