While numerous studies have revealed that arbuscular mycorrhizal fungi (AMF) enhance plant performance, the influence of these symbionts on temperate-forest herbaceous species in relation to soil ...physical and chemical properties has been left largely unexplored. Therefore, two perennial herbs, Geum urbanum (Rosaceae) and Senecio ovatus (Asteraceae), were examined in a laboratory pot experiment to determine whether AMF influenced their growth, photosynthetic performance index, and N and P contents in biomass. The treatments, involving three widespread AMF species, were prepared in the soils of two habitats colonised by both plants, namely beech and riparian forests, as follows: (1) control-soils without AMF, (2) Claroideoglomus claroideum, (3) Funneliformis geosporus, and (4) Funneliformis mosseae. Neither shoot mass nor photosynthetic performance index of G. urbanum and S. ovatus was enhanced by AMF. Senecio ovatus root mass was increased compared to control only by F. geosporus. Inconsistent effects were observed in N and P contents in shoots and roots of both species. The direction and magnitude of these responses were dependent on the fungal species and soil type. Although the plant species belong to families whose representatives are usually regularly colonised by and highly responsive to AMF, our study indicates that AMF had only a slight impact on the performance of G. urbanum and S. ovatus at the early stages of their development. The plants being slightly dependent on AMF are thus adapted to colonise temperate-forest soils with a low level of availability of AMF propagules.
Salt stress can significantly disrupt the functioning of lichens which are self-sufficient symbiotic organisms inhabiting various severe environments. The aim was to test the effect of salt and ...sucrose on the photosynthetic efficiency of two selected epiphytic lichens inhabiting the interior of the land. Firstly, we compared the effect of salt and sucrose solutions of different concentrations. Secondly, the effect of salt and sucrose solutions with identical osmotic pressures was compared. The results showed that short-term salt stress leads to a significant reduction of
F
V
/F
M
, greater changes in chlorophyll fluorescence parameters and OJIP transients compared to the osmotic effects induced by sucrose. This proved that the negative impact of salt stress is associated primarily with ionic effects. The most symptomatic effect of the ionic stress was a significant reduction of the utilisation of trapped energy in electron transport and thereby down-regulation of electron transfer. Since lichens are resistant to a temporary lack of water, ionic stress could have more serious consequences than osmotic stress itself.
Hypogymnia physodes
was more sensitive to salt stress than
Pseudevernia furfuracea
, but the reduction of photosynthetic efficiency was not permanent since after 24 h
F
V
/F
M
returned to the level characteristic for healthy lichens. Nevertheless, repeated exposure to salt may reduce the vitality of lichens growing along communication routes sprinkled with salt in the winter season. Finally, the changes in certain JIP-test parameters were stronger than
F
V
/F
M
, thus they could be better indicators of salt stress in lichens.
Aim
Overstorey tree species influence both soil properties and microclimate conditions in the forest floor, which in turn can induce changes in ground bryophyte communities. The aim of the study was ...to investigate the effect of tree species identity and the most important habitat factors influencing understorey bryophytes.
Methods
We assessed the effect of 14 tree species and related habitat parameters, including soil parameters, vascular plant presence and light intensity on bryophytes in monospecific plots covered by nearly fifty-year-old trees in the Siemianice Experimental Forest (Poland).
Results
The canopy tree species determined bryophyte species richness and cover. The strongest differences were observed between plots with deciduous and coniferous trees. Soils with a more acidic pH and lower content of macronutrients supported larger bryophyte coverage. We also found a positive correlations between vascular plants and availability of light as well as bryophyte species richness.
Conclusion
Tree species identity and differences in habitat conditions in the forest floor lead to changes of ground bryophyte richness, cover and species composition. Consequently, the changes in the dominant tree species in the stand may result in significant repercussions on ground bryophyte communities. We indicated that the introduction of alien tree species, i.e.
Quercus rubra
, has an adverse effect on bryophyte communities and suggested that the selection of tree species that contribute to the community consistent with the potential natural vegetation is highly beneficial for maintaining ground bryophyte biodiversity.
Aims The aim of this study was to determine relationships between soil chemical parameters (i.e. content of total organic carbon, total nitrogen, total sulphur, soil pH) and vegetation development in ...relation to distance from the current glacier forehead and time elapsed after glacier retreat in the Irenebreen foreland. Methods Three transects were designated along the foreland. Species and vegetation cover were investigated in 1 m2 plots, placed every 50 m along each transect; corresponding soil samples were collected and chemically analysed. Results The total organic carbon and total nitrogen contents in soil change according to power and exponential functions, respectively, whereas soil pH decreases linearly with increased time elapsed after glacier retreat. The wide variation in total sulphur contents prevent the determination of clear relationships. Bryophytes and vascular plants dominate in the younger part of the foreland, whereas epigeic lichens prevail in the older part. Conclusions Vegetation cover seems to be the main factor effects on soil properties; however, chemical soil properties and distance from the glacier forehead affect species distribution and vegetation cover. Considered so far as the first pioneers, the epigeic lichens need more time than bryophytes and vascular plants to colonise the foreland.
Background and Aims Viola tricolor L. (heartsease, wild pansy) is a valuable medicinal plant obtained for pharmaceutical purposes by cultivation. Given that the species is usually strongly colonized ...by arbuscular mycorrhizal fungi (AMF), we tested in a pot experiment whether these microorganisms were able to influence V. tricolor mass, vitality, and the concentrations of selected elements, phenolic acids and flavonoids. Methods The following treatments were prepared: (1) control: sterile soil without AMF inoculation; (2) Rhizophagus irregularis BEG144; (3) Funneliformis mosseae BEG12; and (4) both isolates. Using a combination of physiological, phytochemical and biophysical methods, we evaluated the effects of these AMF on the performance of heartsease. Results The intensity of mycorrhizal colonization and arbuscule formation was higher when F. mosseae and R. irregularis were introduced separately than when both isolates were present. None of the AMF treatments had an impact either on V. tricolor vitality as expressed by photosynthetic performance index (PI) or on its shoot and root mass. However, in general, a negative correlation was found between the extent of mycorrhizal colonization and shoot mass. We found AMF species specificities in their influence on element, phenolic acid and flavonoid concentrations. Viola tricolor showed no response to F. mosseae. The plants inoculated with R. irregularis had higher concentrations of P, Zn, Mg, and Ca, as well as p-hydroxybenzoic acid and rutin, in comparison to control. Dual AMF species inoculation increased concentrations of Cu, Mg and rutin. Conclusions The enhanced production of secondary metabolites in V. tricolor shoots may be due to improved mineral nutrition by AMF and/or a result of general plant defense reaction to fungal colonization. The tendency towards biomass decrease in AMF treatments could be explained by the allocation of plant carbon both to the maintenance of symbionts and enhanced production of secondary compounds.
Riparian zones are very rich in species but subjected to strong anthropogenic changes and extremely prone to alien plant invasions, which are considered to be a serious threat to biodiversity. Our ...aim was to determine the spatial distribution of Chenopodium ficifolium, a species demonstrating strong confinement to large river valleys in Central Europe and an indicator of annual pioneer nitrophilous vegetation developing on river banks, which are considered to be of importance to the European Community. Additionally, the habitat preferences of the species were analysed. Differences in the richness and abundance of species diagnostic for riverside habitats, as well as the contribution of resident and invasive alien species in vegetation plots along three rivers differing in terms of size and anthropogenic impact were also examined. Finally, the effect of invaders on the phytocoenoses typical for C. ficifolium was assessed. The frequency of C. ficifolium clearly decreased with an increasing distance from the river. Among natural habitats, the species mostly preferred the banks of large rivers. The vegetation plots developing on the banks of the three studied rivers differed in total species richness, the number and cover of resident, diagnostic and invasive alien species, as well as in species composition. Our research indicates that abiotic and anthropogenic factors are the most significant drivers of species richness and plant cover of riverbank vegetation, and invasive alien plants affect this type of vegetation to a small extent.
Phenotypic traits of lichens can be greatly modified by environmental factors. Granulose thalli on soil and podetia, densely covered with granules, referring to common and widespread lichen
Cladonia ...cervicornis
subsp.
verticillata
were found near zinc smelter. The granules are stratified, filled with fungal medulla and heavily encrusted with calcium oxalate weddellite crystals, not observed on regularly developed thalli of the species. Phylogenetic analysis revealed that deformed granulose forms belong to this taxon, showing that the phenotypic plasticity of the lichens of
Cladonia
can lead to the emergence of features that do not coincide with the taxonomic definition of the species. The heavy-metal accumulation capacity of both granulose and regular form of primary and secondary lichen thallus, in relation to the element content in corresponding substrate, was determined. Granulose-modified thalli accumulate greater amounts of heavy metals than regular ones, meaning that the bioaccumulation property of a given species may be greatly affected by morphological modifications. The granulose forms are also characterised by considerably higher ratios of Cd, Pb and As concentrations in lichen samples in relation to the corresponding substrates than regular ones. This means that collection of variously formed thalli should be avoided in biomonitoring sampling procedures. The results indicate that a substantial part of the element load, in particular zinc, in the examined lichen thalli collected near the smelter originates from atmospheric fallout.
No studies have compared so far the effects of alien invasive and expansive native (widespread, mono-dominant) plants on arbuscular mycorrhizal fungi (AMF). Four global or European most successful ...invaders (
Impatiens glandulifera
,
Reynoutria japonica
,
Rudbeckia laciniata
,
Solidago gigantea
) and two expansive plants native to Europe (
Artemisia vulgaris
,
Phalaris arundinacea
) were grown in pots to elucidate the magnitude and direction of changes in AMF abundance, species richness, and species composition in soils from under multispecies native vegetation. In a second stage, the effects of these changes on a native plant,
Plantago lanceolata
, were assessed. Plant species identity had larger impact on AMF abundance, species richness, and species composition as well as on
P. lanceolata
than origin of the species (alien vs. native). This could be due to the character of AMF relationships with the plants, i.e., their mycorrhizal status and dependency on AMF. However, the alterations induced by the plant species in soil chemical properties rather than in AMF community were the major drivers of differences in shoot mass and photosynthetic performance of
P. lanceolata
. We determined that the plants produced species-specific effects on soil properties that, in turn, resulted in species-specific soil feedbacks on the native plant. These effects were not consistent within groups of invaders or natives.
Based on numerical analyses of macromorphological characters (cluster analysis, principal coordinate analysis and principal component analysis), scanning electron microscopy observation of lemma and ...lamina micromorphology, as well as field observations, five taxa belonging to the Stipa turkestanica group have been recognized in the mountain area of Central Asia. They are S. turkestanica subsp. turkestanica, S. turkestanica subsp. trichoides, S. macroglossa subsp. macroglossa, S. macroglossa subsp. kazachstanica and S. kirghisorum. As a result of this study, we propose one new combination, S. macroglossa var. pubescens, and designate lectotypes for S. turkestanica subsp. trichoides and S. macroglossa var. pubescens, and an epitype for S. kirghisorum. Illustrations of micromorphological structures of the lemma, patterns of leaf hairiness and an identification key are provided. A taxonomic synopsis including information on nomenclatural types, synonyms, descriptions of the taxa, and, as supplementary information, a list of the specimens examined is also presented.
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•Heavy-metal deposition patterns in lichen thalli were determined.•Zn, Pb, Cd were accumulated mostly extracellularly, whereas Cu and Ni intracellularly.•At high polluted sites, Zn ...was accumulated in a similar way to toxic elements.•Metal accumulation depend on the element and its abundance in the environment.•Non-linear models reflect relations between intra- and extracellular metal contents.
Heavy metals that pass through the plasmalemma are expected to influence on lichen metabolic processes; however, lichens may tolerate high concentrations of metals by sequestrating them extracellularly. Heavy metal accumulation level fundamentally determine the success of lichens in the colonisation of polluted sites; however, the proportions between extra- and intracellular metal concentrations in lichen thalli are still poorly recognized. In this study metal accumulation patterns of selected toxic trace elements, i.e. Pb, Cd, and micronutrients, i.e. Zn, Cu and Ni, in Cladonia cariosa thalli were recognised in relation to extra- and intracellular fractions.
The intracellular and total concentrations of Zn, Pb, Cd, Cu and Ni in lichen thalli collected from eleven variously polluted sites were determined by means of atomic absorption spectrometry. Additionally, organic carbon and total nitrogen contents as well as pH of soil substrate were measured.
The accumulation patterns differed between studied metal elements; the major part of Zn, Pb and Cd loads was accumulated extracellularly, whereas Cu and Ni accumulation was mostly intracellular. Like toxic trace elements, Zn was accumulated mainly extracellularly at high polluted sites. The non-linear models most reliably reflect relationships between intracellular and extracellular metal contents in C. cariosa thalli. The intracellular contents of Zn, Pb, Cd and Cu increased slower at higher than at lower extracellular concentrations. Moreover, at higher total concentrations of elements in the thalli, their extracellular proportions were markedly increased.
The results suggest that in the face of extreme Zn-enrichment, lichens demonstrate the ability to accumulate the excess of Zn outside the cells. Therefore, it can be concluded that metal accumulation depend not only on the element but also on its abundance in the environment and direct availability for lichens. The studied species showed a defence against excessive intracellular accumulation when a given element is in excess. Such capability may facilitate the colonization of extremely polluted sites by certain pioneer lichens.
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