Agnieszka Piernik

Micropattern of halophytic vegetation on technogenic soils affected by the soda industry

Abstract The properties of technogenic soils affected by the soda industry are significantly different from natural saline soils occurring in Poland. The long-term impact of post-production waste contributed to the formation of extremely saline soils rich both in sodium chloride (NaCl) and calcium chloride (CaCl2). Despite the strong degradation, these soils play a very important role in the urban ecosystem, because they can provide a habitat for very unique halophytic species. Therefore, in this study, we examined how environmental factors control the micropattern of halophytic vegetation in analyzed industrial soils in Poland. It was hypothesized that species distribution and vegetation variation can be affected by different environmental factors at the local scale. The current study was carried out on three test plots of different microelevation and vegetation cover. In general, Salicornia europaea L. was the most dominant species on each plot, but besides patches dominated only by this species, the other major and distinguished constituents were Puccinelia distans, (JACQ.) PARL. Aster tripolium L. and Triglochin maritima L. Finally, the general vegetation–environmental statistical model (direct ordination–redundancy analysis) was created. The results demonstrated that very diverse microtopography and soil conditions within very small areas were ecologically important. The driving factors for species distribution on each plot were slightly different because of the local differences in environmental conditions. The generalization of vegetation–environment relations performed for all plots together demonstrated that significant, and the most important, factors for plant species distribution in the investigated area were elevation and parameters determined in the saturation paste extracts such as reaction (pHe), chloride content (Cl-) and saturation percentage (SP). As a general rule, species preferred elevated parts of the lower salinity (ECe) and the lower concentration of chloride (Cl–) ions. S. europaea was present at relatively higher salinity compared to A. tripolium, T. maritima and P. distans. Moreover, the presence of P. distans was related to the relatively higher soil pH. The obtained results in the association context present the factors responsible for species variation within the Salicornia europaea plant community, which can be particularly important for restoration of its natural stands.

Metabolic profiles of microorganisms associated with the halophyte Salicornia europaea in soils with different levels of salinity

Abstract: Plants have evolved a wide range of adaptation mechanisms that enable them to grow and develop in environments of high soil salinity. We examine the plant—microbial interactions of Salicornia europaea (Herbaceae) as potential mechanisms responsible for the high tolerance of halophytes to saline conditions. We evaluated the impact of different NaCl concentrations on microorganisms associated with S. europaea growing at 2 saline sites in central Poland: a salty meadow in the vicinity of a soda factory (anthropogenic salinity) and an area affected by natural brine (landscape park). The community-level physiological profiles of microorganisms associated with the plant were determined for endophytes from the roots, rhizosphere, and salt-affected soil. The highest total microbial metabolic activity, irrespective of the test site, was always in the rhizosphere, while the activity of endophytic and soil populations depended on salinity. In general, a higher total metabolic activity was observed at the test site exhibiting higher salt concentration. We propose that increased metabolic activity of microbial populations under increased salt stress can significantly contribute to the site adaptation of halophytes to saline conditions.

Functional traits and environmental characteristics drive the degree of competitive intransitivity in European saltmarsh plant communities

Competitive intransitivity, the existence of loops in competitive hierarchies, is one mechanism that can promote the local coexistence of competitors and maintain high local species diversity, although its prevalence and importance remain largely unknown. A full understanding of local community assembly needs knowledge of how transitive and intransitive competitive interactions are linked to species functional traits and the strength of biotic and abiotic filters. We apply a recently developed statistical tool to quantitative data on central European inland saltmarsh plant communities to infer causal relationships between soil characteristics, species occurrences and functional traits, and we estimated coefficients of competition. We found a predominance of intransitive competitive hierarchies. The proportion of such hierarchies was positively correlated with local species richness and compositional variability. Average soil characteristics were not correlated with competitive intransitivity, whereas high soil pH and the high variability in local pH and soil salinity decreased the overall impact of competition on community composition. In pairwise comparisons of species, dissimilarity in morphology, resource demand and reproductive phenology was significantly negatively correlated with differences in competitive performance, while higher environmental dissimilarity was particularly linked to intermediate degrees of competitive superiority. Our results suggest that habitat filtering for similar traits might intensify competitive interactions, but might also give rise to intransitive competitive loops that subsequently promote species coexistence and permit species’ functional equivalence. Intransitive competition appears to increase local diversity and small scale‐species turnover. The observed local differences in competitive structures suggest frequent competitive plasticity and context‐dependent competitive interactions. Finally, our results support the view that local abundance distributions can be used to infer the strength and outcome of competitive interactions. Synthesis. Our results confirm that intransitive competitive interactions might be a strong force structuring local plant communities. Intransitivity needs to be considered when studying plant community assembly and species co‐existence.

Ectomycorrhizal and endophytic fungi associated with Alnus glutinosa growing in a saline area of central Poland

Alnus glutinosa (black alder) is a mycorrhizal pioneer tree species with tolerance to high concentrations of salt in the soil and can therefore be considered to be an important tree for the regeneration of forests areas devastated by excessive salt. However, there is still a lack of information about the ectomycorrhizal fungi (EMF) associated with mature individuals of A. glutinosa growing in natural saline conditions. The main objective of this study was to test the effect of soil salinity and other physicochemical parameters on root tips colonized by EMF, as well as on the species richness and diversity of an EMF community associated with A. glutinosa growing in natural conditions. We identified a significant effect of soil salinity (expressed as electrical conductivity: ECe and EC1:5) on fungal taxa but not on the total level of EM fungal colonization on roots. Increasing soil salinity promoted dark-coloured EMF belonging to the order Thelephorales (Tomentella sp. and Thelephora sp.). These fungi are also commonly found in soils polluted with heavy-metal. The ability of these fungi to grow in contaminated soil may be due to the presence of melanine, a natural dark pigment and common wall component of the Thelephoraceae that is known to act as a protective interface between fungal metabolism and biotic and abiotic environmental stressors. Moreover, increased colonization of fungi belonging to the class of Leotiomycetes and Sordiomycetes, known as endophytic fungal species, was observed at the test sites, that contained a larger content of total phosphorus. This observation confirms the ability of commonly known endophytic fungi to form ectomycorrhizal structures on the roots of A. glutinosa under saline stress conditions.

Effect of halotolerant endophytic bacteria isolated from Salicornia europaea L. on the growth of fodder beet (Beta vulgaris L.) under salt stress

ABSTRACT The aim of this study was to determine the influence of selected halotolerant endophytic bacteria isolated from the roots of Salicornia europaea on the growth parameters of Beta vulgaris under different concentrations of salinity. Two endophytic strains were selected as inocula for the pot experiment: Pseudomonas sp. ISE-12 (B1) and Xanthomonadales sp. CSE-34 (B2). Surface-sterilised seeds were incubated in the bacterial inoculation suspensions before sowing and cultivated in a sterile mixture of sand and vermiculite (1:1). Six salinity treatments were taken into account: 0, 50, 100, 150, 200 and 300 mM NaCl. Inoculation of seeds with B1 and B2 positively affected germination percentage and germination index and shortened mean germination time, which led to a quickening of the growth stages of seedlings. After 42 days inoculated plants had, in general, a greater root length, higher dry biomass, lower tissue water content and lower specific leaf area compared with the control. While the positive effect of B2 bacteria was visible only at low salinity, strain B1 stimulated plant growth at higher salinities (200 and 300 mM NaCl). We suggest that the superior growth promotion observed for B1 may be related to the higher metabolic activity of these bacteria.

How Does Salinity Shape Bacterial and Fungal Microbiomes of Alnus glutinosa Roots

Black alder (Alnus glutinosa Gaertn.) belongs to dual mycorrhizal trees, forming ectomycorrhizal (EM) and arbuscular (AM) root structures, as well as represents actinorrhizal plants that associate with nitrogen-fixing actinomycete Frankia sp. We hypothesized that the unique ternary structure of symbionts can influence community structure of other plant-associated microorganisms (bacterial and fungal endophytes), particularly under seasonally changing salinity in A. glutinosa roots. In our study we analyzed black alder root bacterial and fungal microbiome present at two forest test sites (saline and non-saline) in two different seasons (spring and fall). The dominant type of root microsymbionts of alder were ectomycorrhizal fungi, whose distribution depended on site (salinity): Tomentella, Lactarius, and Phialocephala were more abundant at the saline site. Mortierella and Naucoria (representatives of saprotrophs or endophytes) displayed the opposite tendency. Arbuscular mycorrhizal fungi belonged to Glomeromycota (orders Paraglomales and Glomales), however, they represented less than 1% of all identified fungi. Bacterial community structure depended on test site but not on season. Sequences affiliated with Rhodanobacter, Granulicella, and Sphingomonas dominated at the saline site, while Bradyrhizobium and Rhizobium were more abundant at the non-saline site. Moreover, genus Frankia was observed only at the saline site. In conclusion, bacterial and fungal community structure of alder root microsymbionts and endophytes depends on five soil chemical parameters: salinity, phosphorus, pH, saturation percentage (SP) as well as total organic carbon (TOC), and seasonality does not appear to be an important factor shaping microbial communities. Ectomycorrhizal fungi are the most abundant symbionts of mature alders growing in saline soils. However, specific distribution of nitrogen-fixing Frankia (forming root nodules) and association of arbuscular fungi at early stages of plant development should be taken into account in further studies.

Meadow species in the early stages of succession on the ash settler of power plant EDF Toruń SA in Toruń, Poland

The paper is to present the trends of typical species of meadow habitats to colonize the frontier habitats. The area of research is the fly-ash landfills in the power plant EDF Torun SA in Torun. Several times, during the year mix of fly-ashes and slug, resulting from the combustion of coal, is transported by pipeline and this is mixed with water. Floristic research was conducted twice: in 2013 and 2015 year. Within an area of about 7 hectares 84 species of vascular plants (43 species in 2013 and 61 in 2015) were inventoried including 14 characteristic species of meadows. The presence of these species disturbed strong evidence of a wide ecological range and adaptations to survive adverse conditions of habitats. The results demonstrate that meadow species as Festuca arundinacea , Festuca rubra , Lolium perenne , Poa annua, Rumex acetosa and Taraxacum officinale, Poa trivialis and Viccia cracca can be helpful in restoration of fly-ash landfills.