There have been many studies on the impact of urban greenery on perceived danger and preferences, but not many have been conducted in non-English speaking countries. We carried out our research among female university students in Poland, Latvia and China (n = 243), using a photograph rating survey instrument, and presenting slides presenting park landscapes. We compared the impact of the presence of trees and shrubs and their capability of offering concealment, as well as perceived space use intensity on perceived danger and preferences in all three countries. Participants rated the presence of shrubs as a more positive influence on path use intensity and as a negative influence on perceived danger. The link between tree presence and perceived danger in Poland and Latvia is small as well as insignificant in China. In addition, perceived danger turned out to be a mediator of the relations between the presence of trees and shrubs and perceived path use intensity and preference. Our findings support the idea that vegetation in parks could be shaped so that it does not provide place to hide. However, this recommendation is primarily applicable to areas in which the variable ‘perceived danger’ is of importance.

Robinia pseudoacacia L. is an interesting example of how one plant species can be considered invasive or useful depending on its environment. In the past this tree species was planted for decorative purposes and for wood in Poland. For many years it was recommended in poor and degraded habitats because it facilitated late-successional plant species. The aim of this study was to verify if black locust can still be regarded as a resistant tree species in urban greenery. The health condition of old tree specimens growing along streets and in parks was compared. The occurrence of pests and pathogens on R. pseudoacacia trees was assessed and the content of mineral elements in leaves was examined. The research results showed that the health of black locust trees growing in the urban environment in Polish cities, especially along streets (in comparison to park sites), deteriorated significantly due to the interaction of harmful biotic and abiotic factors. Increased level of toxic metals (Fe, Zn, Pb, Mn and Cd) in plant tissues and the accumulation of pests and pathogens negatively influenced the health of R. pseudoacacia.

The aim of this study was to determine the impact of safety-related environmental characteristics in a city park on users’ preferences and whether this impact can be explained by perceived safety. The factors examined were physical and visual accessibility as well as the effectiveness of concealment created by plants in various spatial systems. We used 112 photographs taken in city parks for the study. Studies have shown that visual and physical accessibility varies in terms of impact on preferences and safety—as a result, we tested only visual accessibility and effectiveness. Correlation and regression analyses confirmed that vegetation in a park that obstructs views and can offer concealment reduces our sense of safety. In addition, such vegetation has a negative effect on preference. However, mediation analysis showed that this sense of safety or danger means that dense vegetation (low visual accessibility yet highly effective in offering concealment) is less preferred as a landscape feature. After excluding the impact brought to bear by the sense of safety, the studied features of vegetation had no significant impact on preferences. This means that plants and vegetation layouts of varying densities can be used in completely safe parks and this will probably not adversely affect the feelings of the users.

Green roofs have received much attention in recent years due to their ability to retain rainwater, increase urban diversity, and mitigate climate change in cities. This interdisciplinary study was carried out on three historical green roofs covering bunkers in Wrocław, located in southwestern Poland. It presents the results of a three-year investigation of the water storage of these roofs. The study also presents soil conditions and spontaneous vegetation after their functioning for over 100 years. The soils covering the bunkers are made of sandy, sandy-loam, and loamy-sand deposits. This historical construction ensures good drainage and runoff of rainwater, and is able to absorb torrential rainfall ranging from 100 to 150 mm. It provides suitable conditions for vegetation growth, and forest communities with layers formed there. In their synanthropic flora, species of European deciduous forests dominate, which are characteristic of fresh or moist and eutrophic soils with a neutral reaction. Some invasive species, such as Robinia pseudoacacia, Padus serotina, and Impatiens parviflora, also occur with high abundance. Nowadays, historical green roofs on fortifications, although they have lost their primary military role, are of historical and natural value. These roofs can promote the nonmilitary functions of historical fortifications in order to strengthen the ties between nature and heritage. Protecting and monitoring historical green roofs should be included in the elements of the process of sustainable development and the conservation of these structures in order to mitigate climate change in the outskirts of the city. For this, it is necessary to ensure proper conservational protection, which, in addition to maintaining the original structure, profiles, and layout of the building, should include protection of their natural value.

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