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Species composition of lawns in the housing estates, planted – among other reasons – in order to diversify the urban landscape, is often modified and enriched with other, spontaneously appearing species. The aim of the present work was to determine the floristic and phytosociological diversity of selected housing estate lawns of three different age groups, in the city of Szczecin, in three neighbouring housing estates (Niebuszewo, Warszewo, and Żelechowa). It was assumed that over the years, lawns are gradually becoming weaker, which may be due to the occurrence of negative anthropogenic factors of increasing intensity. It was found that despite the one designated plant community in all the analysed housing estate lawns (namely, Poa pratensis – Festuca rubra), there are differences between the studied areas, in terms of the number of species occurring therein, and the values of selected ecological (environmental) indicators.
The aim of the study was to assess how the proportion of dicotyledons in the lawn was influenced by aboveground biomass containing Festuca rubra, cv. ‘Areta’, ‘Nimba’, and ‘Olivia’, cut and left on the lawn surface. This influence was evaluated based on the changes in the species composition of the lawn sward. In the control treatments, the cut turf was removed from the lawn surface immediately after cutting. The study showed that the botanical composition of the lawn varied and depended on the cultivar of F. rubra and the assessment date. In the treatments where the cut turf with F. rubra ‘Areta’ and ‘Olivia’ was not removed, grasses were found to have a higher proportion than dicotyledons and other unsown species, both in the spring and autumn. In the treatments with ‘Nimba’, this effect was only observed in the autumn. ‘Nimba’ demonstrated the greatest ability to limit the proportion of dicotyledons in the lawn sward.
This paper aims to verify the hypothesis that magpies in urban environments favour poplars as nesting trees, as suggested by previous authors. The fieldwork was conducted in a 180 ha area in a district of Gdańsk (North Poland). The study area held 5294 trees and high shrubs, where 124 magpie nests were found in 10 species of trees. Results of log-linear analysis showed that the magpies chose particular tree species rather than types of spatial tree organization. The lombardy poplar (Populus nigra “Italica”) is the species most frequently chosen as a nest tree, however – the magpies showed a significant preference for trees growing separately or in pairs. The choice index (the ratio of expected to observed frequency) confirmed the magpies’ strong preference for black poplar cultivars and for birches, regardless of the trees’ grouping. The magpies preferred lombardy poplar when they had the choice of two poplar cultivars. This cultivar has a crown suitable for the magpie’s nest construction because of the small angle between the trunk and the branches. The thin, almost vertical branches probably also limit predators from penetrating the crown because these branches do not provide much support for tree climbers. The large-scale planting of lombardy poplars in Polish towns in the 1960s and 1970s has probably contributed to the significant increase of the magpie population in the urban environment.
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