Petr Plohák

The article focuses on allelopathic interactions between plants. It presents the results of the effect of biological extracts from Solidago canadensis and Robinia pseudoacacia on seedlings of Lepidium sativum and Solidago canadensis. Solidago canadensis extracts inhibit the growth of Lepidium sativum, while Robinia pseudoacacia extracts stimulate the growth of Lepidium sativum. The application of Solidago canadensis extracts to Solidago canadensis seedlings showed signs of autotoxicity.

The D1 Paskov spoil heap is a smaller brownfield covering an area of 71,188 m², located in the former Paskov mining region. It serves as a model area for reclamation planning, based on a comprehensive assessment of its natural conditions and the risks posed by contamination from hazardous elements and erosion processes. Data for this assessment was collected through field research conducted between 2023 and 2025. In September 2023, additional fieldwork and mapping were carried out using unmanned aerial vehicles equipped with two types of sensors: an RGB camera and LiDAR. The dump is primarily covered with ruderal vegetation, with the summit plateau dominated by the expansive grass species Calamagrostis epigejos. With appropriate management, the plant communities on the western and northern slopes have the potential to develop into conservation-significant habitats. However, the southwestern slope presents challenges due to active rill erosion and contamination. Stabilization measures are required to prevent further degradation in this area.

As a result of hard coal mining, specific areas of subsidence basins, which are often waterlogged, were created in the Czech part of the Upper Silesian Coal District. These areas may not have a high ecological value or, on the contrary, promising biotopes may arise here under suitable conditions, which should be our goal. As part of this work, the above-ground vegetation, and the soil seed bank (using the cultivation method) were investigated. The concentration of the risk elements chromium and arsenic, which are usually increased in mining areas, was determined by neutron activation analysis. Other environmental variables that can affect both the vegetation and the soil seed bank of subsidence basins (fine earth, slope, biotopes, and their representation in the vicinity) were also determined. Using multivariate DCA analysis, a statistically significant influence of chromium concentration and other variables on above-ground vegetation, characterized by the occurrence of many metallophytes and their high coverage, was found. The soil seed bank, which can impact the further development of vegetation, is mainly influenced by forest and wetland biotopes and the representation of areas covered by tailings in the vicinity of sampling sites. It is evident that there are species capable of resisting or accumulating chromium and arsenic pollution in both the above-ground vegetation and the soil seed bank, which can lead to the gradual rehabilitation of subsidence basins. This research can lead to a better understanding of the development of subsidence basins to increase their future ecological values.

Overall amount and quality of seeds reaching the area is an important factor in the development of plant communities in each habitat. It can be a significant source of diversity in anthropogenically disturbed areas. This study is focused on the survey of seed rain in habitats of waterlogged subsidence basins of the Karviná region, induced by deformations of overlying rocks in the area of deep coal mining. The density, species composition and dispersal strategies of captured seeds were monitored using funnel traps with a 35 cm diameter, fixed at a height of 0.5 m. A vegetation study was conducted to compare seed rain with above-ground vegetation using the Jaccard similarity index. Over 11 000 seeds of 27 plant species were captured in total. Seed rain was dominated by Salix alba species. Seed density varied significantly within individual sampling plots (7–12380 seeds/m2) with the average richness of four species. The diversity of above-ground vegetation was also low, with an average of 15 species per plot (100 m2). Similarity between seed rain and above-ground vegetation of subsidence basins is 27.6 % and 52 % within the woody species community. It is evident that the seed rain of waterlogged subsidence basins contains species of floodplain forests and wetland vegetation. On the other hand, invasive and expansive species identified both in seed rain and above-ground vegetation can potentially endanger the development of the succession of these habitats. The analysis of seed dispersal also shows a significant proportion of species of arid and mesic habitats. Keywords: Dispersal strategy; Karviná; Seed rain; Subsidence basin.