• Energy Research

Grasses have considerable potential for adaptation to various often extreme habitat conditions. The aim of the work is to present the vegetation diversity of the coal-mine spoil heaps with the dominant share of grasses and to identify the main factors responsible for this diversity in the aspect of post-industrial land reclamation. The communities differ in reference of species preferences to light, moisture, soil fertility and reaction, what is reflected in the wide variety of microhabitats in the area. It has been shown that the increase in abundance of certain grass species Calamagrostis epigejos, Festuca rubra, Festuca arundinacea, Phragmites australis has a significant negative impact on the species richness, species diversity and the uniformity of distribution of species of the plant community. Preliminary analyzes revealed that on post-mining waste biomass production of the dominant species is negatively correlated with biodiversity. Knowledge about biology and ecology of grass species, as well as, on the assembly rules may be used in the reclamation of degraded areas. Gaining knowledge about the vegetation diversity of the coal-mine spoil heaps with the dominant share of grass can be useful in planning reclamation works taking into account natural processes, which leads to the creation of a permanent vegetation cover in the area, protecting it against water or wind erosion, and in the future these areas may provide a number of important ecosystem services.

Abstract Dominant species influence both species and functional composition of the vegetation as well as soil properties of the substrate. However, knowledge about the role played by dominant species in the process of shaping their habitat within post-industrial ecosystems is still limited. We aimed to assess the impact of four dominant species (Calamagrostis epigejos, Daucus carota, Poa compressa and Tussilago farfara) on soil abiotic and biotic properties, and to detect differences in species and functional composition of the vegetation types studied. We hypothesized that (1) dominant species of higher mean biomass cause lower aboveground biodiversity and (2) dominant species of higher mean biomass have a higher impact than the others on soil properties. We measured soil chemistry (TOC, N, P, K, Na, Mg content, EC, pH and enzyme activities) as well as biomass, species diversity and functional diversity of vegetation on 15 study plots (28.3 m2) for each species studied. The DCA analysis revealed a clear distinction between the patches dominated by studied species. Vegetation patches dominated by Calamagrostis epigejos were correlated with amount of biomass, canopy height CWM and specific leaf CWM. Patches dominated by Daucus carota were related to the light requirements (EIV-L), Total Organic Carbon (TOC) and K content. The vegetation patches dominated by Poa compressa were related to dehydrogenase activity, higher Mg content and species richness of the vegetation patches. The highest TOC content was recorded for T. farfara substrates, and the lowest for C. epigejos substrates. The content of potassium does not differ statistically significantly in the substrates from sites dominated by D. carota and P. compressa. The highest values of Mg content were recorded for D. carota and were statistically different from Poa compressa sites, while the higher phosphorus content (statistically significantly different) was recorded for patches dominated by T. farfara and P. compressa. Despite our assumptions, the species with the highest mean biomass (Calamagrostis epigejos) did not cause lower species or functional diversity. In contrast, Tussilago farfara has the highest impact on postindustrial site habitats on coal mine heaps, as extreme values of four soil substratum parameters were recorded on these plots. This species also decreased both species and functional diversity of vegetation. The knowledge about relationship existing between plants (aboveground vegetation) and soil organisms seems important in order to undertake suitable reclamation measures and to restore variety of functions as well as to create diverse vegetation based on native species.

GABA (gamma-aminobutyric acid) and melatonin are endogenous compounds that enhance plant responses to abiotic stresses. The response of Vicia faba to different stressors (salinity (NaCl), poly ethylene glycol (PEG), and sulfur dioxide (SO2)) was studied after priming with sole application of GABA and melatonin or their co-application (GABA + melatonin). Both melatonin and GABA and their co-application increased leaf area, number of flowers, shoot dry and fresh weight, and total biomass. Plants treated with GABA, melatonin, and GABA + melatonin developed larger stomata with wider aperture compared to the stomata of control plants. The functionality of the photosynthetic system was improved in primed plants. To investigate the photosynthetic functionality in details, the leaf samples of primed plants were exposed to different stressors, including SO2, PEG, and NaCl. The maximum quantum yield of photosystem II (PS II) was higher in the leaf samples of primed plants, while the non-photochemical quenching (NPQ) of primed plants was decreased when leaf samples were exposed to the stressors. Correlation analysis showed the association of initial PIabs with post-stress FV/FM and NPQ. Stressors attenuated the association of initial PIabs with both FV/FM and NPQ, while priming plants with GABA, melatonin, or GABA + melatonin minimized the effect of stressors by attenuating these correlations. In conclusion, priming plants with both GABA and melatonin improved growth and photosynthetic performance of Vicia faba and mitigated the effects of abiotic stressors on the photosynthetic performance.