Forests are very important elements in the ecological structure of cities and rural areas. They are reservoirs of flora and fauna biodiversity in the ecological system (Sanesi et al. 2017). Urbanisation is a process which causes many changes in the environment, such as habitat fragmentations, temperature increase and soil compaction (Patarkalashvili 2017; Wang et al. 2020). Anthropogenic activities mainly affect semi-natural and natural ecosystems (Faliński 1966; Kornaś 1968; Sokołowski 1972; Sudnik-Wójcikoska and Galera 2005). Plant cover is often altered by displacing and depleting native species and appearance of species incompatible with the natural habitat. This process is highly undesirable in natural habitats and often leads to irreversible changes in forest ecosystems as well (Lundholm and Marlin 2006; Gonzalez et al. 2010; Zhou et al. 2018; Fornal-Pieniak et al. 2019). Herbaceous plants are very dynamic with respect to habitat changes within a short period of time. Therefore, they are suitable indicators of changes in plant association (Hofmeister et al. 2013). It is important to identify consistent plant species, which are an important indicator of forest naturalness. The purpose of this study was to analyse the composition of vascular plant species in the herb layer of ecotone's selected urban forests and forests outside the city.
Field studies were carried out in the years 2019–2020, including two seasonal aspects, spring and summer, in eight forests located in Brzesko city and outside the city. Brzesko city has got a surface area of 11.83 km2; and has 16,819 inhabitatns. (
Map of the location of Brzesko city (a) and the studied forests (A1, A2, A3, A4 – non-urban forests; B1, B2, B3, B4 – urban forests) (b) in this city
It distinguished 15 study plots (phytosociological records were made according to the Braun-Blanquet method (Braun-Blanquet 1951)), with an area of 100 m2 in each forest. In total, 60 phytosociological records were made in urban forests and 60 phytosociological records were made in forests outside the city (available from author(s) on request). The identified plant species were grouped according to the degree of compliance with the natural habitat. We distinguished consistent species represented by forest species, which including tree, shrub, herb and grass species, which are typical for
To compare the occurrence of individual herbaceous species, its frequency in individual forests was determined as the share of research plots where the species was found within all plots in a given forest. The analyses were performed using the STATISTICA 13.0 package. A simple c2 test was also used to distinguish forest herbaceous species characteristic/diagnostic of urban and non-urban forests.
The mean number of vascular plant species (20) was higher (
The list of vascular plant species which occurred significantly (c2 test,
Forest species | Urban forests | Non-urban forests |
---|---|---|
65 | 78 | |
51 | 72 | |
51 | 77 | |
51 | 70 | |
48 | 71 | |
42 | 78 | |
40 | 60 | |
29 | 52 | |
0 | 61 | |
0 | 60 |
The composition of vascular plant species in the herb layer was dominated by forest species, consistent with
The share of forest, grass, synanthropic and the other plant species in the studied forests (own study)
Urbanisation has got many negative impacts on natural habitats in cities. It causes modifications in the environment as habitat fragmentations, increasing temperature and soil compaction (Patarkalashvili 2017; Wang et al. 2020). The fragmentation of natural habitats leads to transformations and, as a result, to changes in plant species compositions in forests (Dearborn and Kark, 2010). The total number of plants species was higher in forests outside the city than in urban forests. Similar results were obtained by Kowarik et al. (2019).
A higher proportion of grass species was found in forests outside Brzesko city. There were meadows and pastures adjacent to the forests, which could have influenced penetration of inconsistent species from the surrounding areas into the forests. A slightly higher share of synanthropic species typical for urbanised areas and a smaller share of grass species were found in the urban forests of Brzesko city. The number of forest species typical of natural habitat
Surrounding landscape structures have probably higher impact on the collection of plant species not typical for
Flora of urban forests is disturbed more by human influence than the flora outside the city, as evidenced by occurrence of more inconsistent species in the herb layer.
The different land uses shape vascular plant species composition in urban forests and outside the city.
Urban forests form valuable natural shelters for forest species typical of oak–hornbeam habitat.