Tripolium Pannonicum Research Articles

Exploring the Multifaceted Health Benefits of Tripolium pannonicum: Antimicrobial, Antioxidant, and Prebiotic Properties With Phytochemical Insights.

This study investigates the multifaceted potential of Tripolium pannonicum methanolic extract, focusing on its antimicrobial, antioxidant, and prebiotic properties alongside a comprehensive phytochemical analysis. The antioxidant capacity of the methanolic extract was demonstrated through 2,2-diphenyl-1-picrylhydrazyl radical scavenging and iron ion chelating assays, revealing an IC50 value of 0.073mg/mL and 5.79 ± 0.04mg/mL, respectively. Furthermore, the prebiotic activity of T. pannonicum was evaluated, showing enhanced growth of probiotic strains Lactobacillus plantarum and L. fermentum, compared to standard prebiotics, inulin, and fructooligosaccharides. The study also identified 27 bioactive phytochemical compounds in the methanolic extract, including 5-hydroxymethylfurfural and palmitic acid, which were further explored through molecular docking analyses, revealing significant interactions with the human pregnane X receptor. These findings underscore the potential of T. pannonicum as a sustainable health solution in both agricultural and medicinal contexts, warranting further exploration of its therapeutic applications and mechanisms of action.

Structural Elucidation and Antiviral Properties of Pannosides from the Halophyte Aster tripolium L.

Four previously undescribed pentacyclic triterpenoid saponins, pannosides F-I (1-4), were isolated from the halophyte Aster tripolium L. (Tripolium pannonicum), and their chemical structures were elucidated using 1D and 2D NMR spectroscopy and mass spectrometry. Comprehensive structural analysis revealed the presence of distinct aglycone and glycosidic moieties, along with complex acylation patterns. The acyl chains of pannosides, 3-hydroxybutyrate (3-HB) residues, were derivatized with (S)- and (R)- phenylglycine methyl ester to resolve the absolute configurations of the chiral centers in 3-HB. Then, the acyl chain-containing saponins, pannosides were evaluated for their antiviral activities against enterovirus A71 (EV71), coxsackievirus B3 (CVB3), and rhinovirus 1B (HRV1B). Pannosides exhibited antiviral activities against HRV1B, EV71, and CVB3. These findings suggest that saponins from A. tripolium exhibit potential antiviral activities and could be further explored for their therapeutic applications.

Parental environment as a factor shaping salinity tolerance in halophyte Tripolium pannonicum L.

Parental environment can significantly influence a range of plant traits across different growth phases and developmental stages. The impact of parental salinity variability on offspring germination and environmental factor response still requires thorough investigation. Therefore, we investigated seeds of Tripolium pannonicum L. from low-saline (Cie) and high-saline (Ino) habitats to elucidate the germination potential and adaptation potential of progeny to varying salinity levels. Germination and growth experiments were conducted to analyze germination parameters, plant areas, water-related traits, the concentration of organic solutes, malondialdehyde, and the activity of crucial oxidative defence enzymes. In the germination experiment, Cie seeds demonstrated higher germination potential with longer germination time under 200–400 mM NaCl compare with Ino seeds. The Cie population achieved the highest shoot and roots area at 100 mM and 300 mM NaCl, respectively. The Ino population exhibited its highest shoot and roots area at 200 mM NaCl. The Ino population indicated an increase in stem cortex cell area at 400 mM NaCl. The Ino population enhanced the synthesis of osmolytes as part of the salinity tolerance mechanism. Antioxidant enzyme analysis indicated higher peroxidase activity in Ino and higher superoxide dismutase activity in Cie under salinity, suggesting distinct enzymatic roles in salinity adaptation between populations. Our findings highlight the critical role of parental environmental conditions in shaping progeny traits, enhancing germination potential, and enabling adaptation of progeny plants to diverse environmental niches. The study underscores population-specific responses to environmental factor, emphasizing the complexity of halophyte adaptation mechanisms to salinity.

Water and nitrogen coupling regulates the present and future restoration trends under Spartina alterniflora invasion in a coastal salt marsh

Global change can easily cause the wetland ecosystem structure and function to be damaged by alien species. Former studies on Spartina alterniflora invasion only focused on the effect of aboveground communities, ignoring the potential regeneration of soil seed banks. Therefore, the study aimed to find the key resources that limit the S. alterniflora invasion and the regulation mechanism for S. alterniflora regeneration. Through investigating the S. alterniflora communities with different invasion stages, we studied the structure and composition of the aboveground communities and the soil seed banks, in response to the soil properties and water and nitrogen addition. The dominant competitive advantage of S. alterniflora was mainly affected by the aboveground biomass, which was regulated by soil NH4+-N and moisture content. Although the richness was same in the soil seed banks under the S. alterniflora communities with different coverage, S. alterniflora seeds maintained its specific competitive dominance. The niche breadth of S. alterniflora and the niche overlap between S. alterniflora and Tripolium pannonicum was the highest under low aboveground coverage. The soil seed bank germination experiments showed that the S. alterniflora density decreased when the soil nitrogen concentration exceeded 1 g/kg, while the density of native species E. crusgalli and T. pannonicum decreased when the water depth above the soil surface exceeded 2 cm. The successful naturalization of S. alterniflora invasion regulated by nitrogen-water coupling is a bet-hedging of the niche and fitness differences between invasive and native species in the coastal salt marsh of eastern China.

Sulfur-Oxidizing Bacteria Alleviate Salt and Cadmium Stress in Halophyte Tripolium pannonicum (Jacq.) Dobrocz.

The aim of this study was to investigate how introducing halophilic sulfur-oxidizing bacteria (SOB) Halothiobacillus halophilus to the growth substrate affects the physiological and biochemical responses of the halophyte Tripolium pannonicum (also known as sea aster or seashore aster) under salt and cadmium stress conditions. This study assessed the plant's response to these stressors and bacterial inoculation by analyzing various factors including the accumulation of elements such as sodium (Na), chloride (Cl), cadmium (Cd) and sulfur (S); growth parameters; levels of photosynthetic pigments, proline and phenolic compounds; the formation of malondialdehyde (MDA); and the plant's potential to scavenge 2,2-Diphenyl-1-picrylhydrazyl (DPPH). The results revealed that bacterial inoculation was effective in mitigating the deleterious effect of cadmium stress on some growth criteria. For instance, stem length was 2-hold higher, the growth tolerance index was 3-fold higher and there was a 20% increase in the content of photosynthetic pigments compared to non-inoculated plants. Furthermore, the SOB contributed to enhancing cadmium tolerance in Tripolium pannonicum by increasing the availability of sulfur in the plant's leaves, which led to the maintenance of an appropriate, about 2-fold-higher level of phenolic compounds (phenylpropanoids and flavonols), as well as chloride ions. The level of MDA decreased after bacterial application in all experimental variants except when both salt and cadmium stress were present. These findings provide novel insights into how halophytes respond to abiotic stress following inoculation of the growth medium with sulfur-oxidizing bacteria. The data suggest that inoculating the substrate with SOB has a beneficial effect on T. pannonicum's tolerance to cadmium stress.

Salt Tolerance and Ion Accumulation in Several Halophytic Plant Species Depending on the Type of Anion

The question of the effect of the anion type on halophyte salt tolerance and ion accumulation is still far from the necessary generalization due to the lack of comparative studies. The aim of the present study was to compare the relatively long-term effect of treatment with various salts formed by different anions on the growth and ion accumulation of several halophyte species in controlled conditions. The main experiments with the largest variety of individual salt types were performed with Cochlearia officinalis L. and two cultivars of Limonium sinuatum (L.) Mill. In addition, experiments with Lobularia maritima (L.) Desv., Plantago maritima L., and Tripolium pannonicum (Jacq.) Dobrocz. focused on the comparison of neutral (NaCl) and alkaline (NaHCO3) salts as well as NaNO3. Acetate salts appeared to be the most toxic, with only Plantago and Tripolium plants being able to withstand full treatment while having a pronounced inhibition in growth. Only the two Limonium cultivars were more susceptible to treatment with alkaline salts in comparison to that with neutral salts. In treatments with alkaline salts, the ion accumulation potential was lower in comparison to plants treated with chlorides and nitrates. It can be concluded that the type of anion is a significant determinant of salinity tolerance and ion accumulation in halophytes, but a high genotype dependence of the responses makes it difficult to generalize the obtained results.

The Sea Aster mining bee Colletes halophilus Verhoeff, 1944 (Hymenoptera: Colletidae) widely distributed at the Baltic Sea coast of Denmark and Germany

The Sea Aster mining bee Colletes halophilus Verhoeff, 1944 is known as an endemic of the western European coasts of the Atlantic and the North Sea. The species has specific habitat requirements and is restricted to coastal habitats with populations of the Sea Aster (Tripolium pannonicum), its preferred host plant. Due to the late summer activity of adults and habitat specialisation, this solitary bee species is easily overlooked. In 2019, C. halophilus was first found at the Baltic Sea coast of the island of Fyn (Denmark), 2020 on the island of Rügen (Mecklenburg-Vorpommern, Germany) and in 2021 in Sehlendorf (Schleswig-Holstein, Germany), demonstrating that the species is far more widespread and also occurring along the more continental Western Baltic Sea coast and Kattegat. Targeted sampling in 2022 revealed that C. halophilus is now present in most of the potentially suitable coastal habitats in Schleswig-Holstein and at least in some parts of Mecklenburg-Vorpommern. We here present data on the currently known distribution of C. halophilus along the Baltic Sea coast of Denmark and Germany and discuss hypotheses of a potential recent range extension.

Harnessing the Value of Tripolium pannonicum and Crithmum maritimum Halophyte Biomass through Integrated Green Biorefinery.

Bioactive extracts are often the target fractions in bioprospecting, and halophyte plants could provide a potential source of feedstock for high-value applications as a part of integrated biorefineries. Tripolium pannonicum (Jacq.) Dobrocz. (sea aster) and Crithmum maritimum L. (sea fennel) are edible plants suggested for biosaline halophyte-based agriculture. After food production and harvesting of fresh leaves for food, the inedible plant fractions could be utilized to produce extracts rich in bioactive phytochemicals to maximize feedstock application and increase the economic feasibility of biomass processing to bioenergy. This study analyzed fresh juice and extracts from screw-pressed sea aster and sea fennel for their different phenolic compounds and pigment concentrations. Antioxidant and enzyme inhibition activities were also tested in vitro. Extracts from sea aster and sea fennel had phenolic contents up to 45.2 mgGAE/gDM and 64.7 mgGAE/gDM, respectively, and exhibited >70% antioxidant activity in several assays. Ethanol extracts also showed >70% inhibition activity against acetylcholinesterase and >50% inhibition of tyrosinase and α-glucosidase. Therefore, these species can be seen as potential feedstocks for further investigations.

Pentacyclic triterpenoids saponins pannosides A-E from Tripolium pannonicum

Five previously undescribed pentacyclic triterpenoid saponins, pannoside A–E (1–5), were discovered from the whole plant of seashore aster, Tripolium pannonicum, collected from the Songdo tidal flat, Incheon, Korea. The planar structures of pannosides were elucidated as pentacyclic triterpenoids bearing sugar moieties and 3-hydroxybutyrate (3-HB) based on the interpretation of the NMR, IR spectroscopic and MS data. The relative configurations of the aglycone and sugar moieties of 1–5 were determined based on careful analysis of ROESY correlations. To determine the absolute configuration of 3-hydroxybutyrate, we utilized the phenylglycine methyl ester (PGME) derivatization with LC-MS chromatographic analysis. Pannoside E (5) exhibited inhibitory activities against diverse cancer cell lines including prostate carcinoma and non-small cell lung carcinoma, with IC50 values of 0.34 and 0.89 μM, respectively. Pannosides are the first triterpenoid saponin isolated from T. pannonicum, implying that undiscovered secondary metabolites from a halophyte could be a good source of bioactive compounds.

Growth Stage-, Organ- and Time-Dependent Salt Tolerance of Halophyte Tripolium pannonicum (Jacq.) Dobrocz.

Tripolium pannonicum (Jacq.) Dobrocz. is a member of the diverse group of halophytes with the potential for the desalination and reclamation of degraded land. The adaptive processes of T. pannonicum to salinity habitats are still not well recognized. Therefore, we evaluated the effect of NaCl (0, 200, 400, and 800 mM) on: (1) two plant growth stages, (2) the activity of antioxidant enzymes and concentration of H2O2 and the proline in roots, stems, and leaves, and (3) the effect of long- and short-term salt stress on physiological responses. Germination, pot experiments, and a biochemical analysis were performed. The effective T. pannonicum's seed germination was achieved in the control. We demonstrated that halophyte's organs do not simply tolerate high-salt conditions. The activities of APX, POD, and catalase observed at 400 mM and 800 mM NaCl were varied between organs and revealed the following pattern: root > leaves > stem. Proline was preferentially accumulated in leaves that were more salt-tolerant than other organs. Salt stress enhanced the activity of antioxidant enzymes and concentrations of salinity stress indicators in a time-dependent manner. Our study has indicated that salt tolerance is a complex mechanism that depends on the growth phase, organs, and duration of salinity exposure. The results have potential for further proteomic and metabolomic analyses of adaptive salt tolerance processes.

Cultivation and characterisation of Salicornia europaea, Tripolium pannonicum and Crithmum maritimum biomass for green biorefinery applications

Salt-tolerant halophytes have shown potential for biorefinery and agricultural use in salt-affected soils, increasing the value of marginal lands. They could provide a bio-based source for compounds obtained from the petrochemical industry or an alternative for biomass currently imported overseas. Salicornia europaea, Tripolium pannonicum and Crithmum maritimum were cultivated in hydroponic systems under various salinity conditions, harvested green but not food-grade, and fractionated to green juice and fibre residue. Obtained fractions were characterised for contents of carbohydrates, Klason lignin, crude protein, organic acids, lipids, and minerals to evaluate the biomass’ suitability for biorefinery. Significant differences were observed in the biomass yield and the composition of the biomass fractions from different cultivation salinities. High concentrations of crude protein were found. Thus, these species could have the potential for green protein production. Fractions rich in carbohydrates could be used for lignocellulose processing and processes utilising micro-organisms.

Thektogaster chrysis (Förster, 1861) added to the British list with first host records for it and other Miscogasterinae (Hymenoptera: Chalcidoidea: Pteromalidae)

New distributional and biological records are provided for wasps in the subfamily Miscogasterinae (Hymenoptera: Pteromalidae), reared from Diptera in Scotland and northern England. Thektogaster chrysis (Förster, 1861) is added to the British list based on specimens reared from Gimnomera tarsea (Fallén) (Scathophagidae), a first host record for the genus. Rhicnocoelia constans (Walker, 1836) is reared from Loxocera sylvatica Meigen (Psilidae), the first European host record for the genus. Nodisoplata diffinis (Walker, 1874) is reared from Egle spp. (Anthomyiidae) in Salix catkins, a first host record for the genus. Ardilea convexa (Walker, 1833) is reared from an Agromyzidae on Tripolium pannonicum, a first host record for the genus.

Halophytic flora and vegetation in southern Moravia and northern Lower Austria

Halophytic habitats are distinctive components of the landscape in southern Moravia, Czech Republic, and the Pulkau valley in northern Lower Austria. We provide a historical overview of their flora and vegetation since the early 19th century and describe the current state assessed in the field at all remaining sites in 2020. We summarized the historical and current distribution of 17 species with the strongest affinity for saline habitats in the study area: Bupleurum tenuissimum, Cirsium brachycephalum, Crypsis aculeata, C. schoenoides, Galatella cana, Glaux maritima, Juncus gerardii, Plantago maritima, Salicornia perennans, Samolus valerandi, Scorzonera parviflora, Spergularia marina, S. media, Suaeda prostrata, Taraxacum bessarabicum, Triglochin maritima and Tripolium pannonicum. Of these, Galatella cana, Salicornia perennans, Suaeda prostrata and Triglochin maritima are regionally extinct. We also characterized the bryoflora typical of saline habitats. We classified historical and newly recorded releves and identified 14 halophytic associations belonging to the alliances Chenopodion rubri, Meliloto dentati-Bolboschoenion maritimi, Cypero-Spergularion salinae, Salicornion prostratae, Puccinellion limosae, Juncion gerardii and Festucion pseudovinae. The vegetation of the alliance Salicornion prostratae had disappeared in the study area by the 1970s. The alliance Festucion pseudovinae, with the association Centaureo pannonicae-Festucetum pseudovinae, was recognized as a new vegetation type for the Czech Republic. Using soil pH and electrical conductivity measurements, we evaluated the relationships of individual species and vegetation types to soil salinity. This synthetic study shows that the once well-developed halophytic flora and vegetation in the study area steadily declined from the early 19th century to the 1980s, initially mainly due to drainage and after the mid-20th century due to the combination of drainage and cessation of grazing. The introduction of conservation management in the 1990s and ecological restoration contributed to stabilizing plant diversity at the last saline sites. The future of halophytic flora and vegetation depends on the continuation of conservation management.

Halophyte Plants and Their Residues as Feedstock for Biogas Production—Chances and Challenges

The importance of green technologies is steadily growing. Salt-tolerant plants have been proposed as energy crops for cultivation on saline lands. Halophytes such as Salicornia europaea, Tripolium pannonicum, Crithmum maritimum and Chenopodium quinoa, among many other species, can be cultivated in saline lands, in coastal areas or for treating saline wastewater, and the biomass might be used for biogas production as an integrated process of biorefining. However, halophytes have different salt tolerance mechanisms, including compartmentalization of salt in the vacuole, leading to an increase of sodium in the plant tissues. The sodium content of halophytes may have an adverse effect on the anaerobic digestion process, which needs adjustments to achieve stable and efficient conversion of the halophytes into biogas. This review gives an overview of the specificities of halophytes that needs to be accounted for using their biomass as feedstocks for biogas plants in order to expand renewable energy production. First, the different physiological mechanisms of halophytes to grow under saline conditions are described, which lead to the characteristic composition of the halophyte biomass, which may influence the biogas production. Next, possible mechanisms to avoid negative effects on the anaerobic digestion process are described, with an overview of full-scale applications. Taking all these aspects into account, halophyte plants have a great potential for biogas and methane production with yields similar to those produced by other energy crops and the simultaneous benefit of utilization of saline soils.

Current Condition of Pannonic Salt Steppes at Their Distribution Limit: What Do Indicator Species Reveal about Habitat Quality?

Little is known about the suite of ecological conditions under which characteristic species may continue to develop under the pressure of recent habitat deterioration. We aimed to determine the niche of three indicator species of the priority habitat Pannonic salt steppes and to find out how their vegetation composition, land use, and soil chemistry mirror the current condition of their typical habitat. A plot-based vegetation survey was conducted in degraded and in pristine (reference) inland salt steppes in East-Central Europe. We confirmed decreased habitat quality at their northern geographical limit. Most of the sites there showed a strong prevalence of generalists (e.g., Elytrigia repens) and lack of specialists, both resulting from lowered habitat extremity and inappropriate land use (abandonment). A small proportion of plots (19%) were in the same good condition as the reference vegetation in the central area. Soil analyses revealed that the studied halophytes are able to persist on desalinized soils if the land use is suitable. The occurrence of the annual Camphorosma annua (Amaranthaceae) was driven largely by abiotic stress; grazing alone is insufficient for its long-term persistence, while the perennial Artemisia santonicum (Asteraceae) and Tripolium pannonicum (Asteraceae) have higher survival chances as they are able to coexist with generalists. Overall habitat quality can be reliably determined from the analyzed ecological conditions of indicator species. The outcomes of the presented work are relevant for conservation practice and can serve as a quick tool for assessing the current stage of other grassland habitats.

Morphology, pollen preferences and DNA-barcoding of five Austrian species in the Colletes succinctus group (Hymenoptera, Apidae)

Most species of the Colletes succinctus group sensu Noskiewicz, 1936 are taxonomically uncertain. This study has chosen an integrative approach, including pollen analysis, morphology, male genitalia, morphometry, cuticle sculpture and DNA-barcoding (CO1) to investigate the five species that were reported from Austria. It includes a detailed analysis of the male genitalia and the first description of the C. pannonicus male. A syntype male from the island of Crete was designated as the lectotype of Colletes succinctus brevigena Noskiewicz, 1936 to fix the species identity. New distinguishing characters were found: in females the shape of the dorsal end of the fovea facialis and, in both sexes, the structure of maxillary palpi, as well as the different puncturation on the mesopleura. Unknown structures on sterna and genitalia of the males proved to be reliable morphological characters. An identification key is provided for all studied species. Morphometry of females did not allow a clear distinction of species. CO1 sequencing confirmed previous studies that only C. collaris clearly deviates from the other species, including C. pannonicus that was analysed for the first time. Pollen analysis showed polylectic, as well as oligolectic, pollen-collecting behaviour. The collected pollen of C. pannonicus confirmed the field observations that this species is strictly oligolectic on Tripolium pannonicum. Due to pronounced intraspecific variation, it is assumed that the species of the C. succinctus group are either species in statu nascendi or very young species. Therefore, it remains important to include ecological data in species identification.

Screening of Emerging Pollutants (EPs) in Estuarine Water and Phytoremediation Capacity of Tripolium pannonicum under Controlled Conditions

The increasing number of pharmaceuticals in the environment and their difficult biodegradation, can lead to bioaccumulation in different trophic compartments. Their bioaccumulation can have negative consequences, especially in the generation of bacterial resistance by antibiotics, but also in the impairment of plant and animal metabolism. The Tejo estuary in Portugal is the habitat for many plant and animal species, which are also prone to this type of contamination. Therefore, in the present study different classes of emerging pollutants (EPs) were surveyed in water samples in the Tejo estuary, including antibiotics, anticonvulsants, antidepressants, lipid-lowering drugs, anti-inflammatory drugs, beta-blockers and analgesics. According to the results, only four compounds were detected in water samples collected at the three selected salt marshes, including carbamazepine, fluoxetine hydrochloride, venlafaxine hydrochloride and acetaminophen. Having the detected substances as a basis, a subsequent study was performed aiming to investigate the uptake and biodegradation capacity of halophytes, using Tripolium pannonicum as a model plant cultivated under controlled conditions with different concentrations of the found EPs. This experimental approach showed that T. pannonicum was able to uptake and degrade xenobiotics. Moreover, the application of sulfamethazine, as a model antibiotic, showed also that this species can uptake and degrade this compound, although the degradation rate and process proved to be compound-specific. This was also confirmed using crude plant extracts spiked with the different EPs. Thus this species is a potential candidate for the remediation of marine water and sediments contaminated with environmentally-significant EPs.

Impact of Water Level on Species Quantity and Composition Grown from the Soil Seed Bank of the Inland Salt Marsh: An Ex-Situ Experiment

The near elimination of inland salt marshes in Central Europe occurred throughout the 19th and 20th centuries, and the currently remaining marshes exist in a degraded condition. This work examines the impact of groundwater level on the growth of plants from a seed bank obtained from a degraded salt marsh in proximity to still existing one through an ex-situ experiment. An experimental tank was set up with the sample seed bank experiencing differing levels of water level. There were 1233 specimens of 44 taxa grown from the seed bank, of which 5 species were abundant, and 10 species are considered as halophytes. Only Lotus tenuis from halophytes was more abundant, and only five species of halophytes were represented by more than three individuals. The water level has a significant impact on the number of species (based on linear regression analysis) as well as species distribution among different water level treatments (a non-metric multidimensional analysis (nMDS) followed by linear regression). The results show a strong negative relationship between the average water level and the number of species. The water level did not affect the species composition of halophytes, but differences in individual species abundances were found among the halophytes. The species Bupleurum tenuissimum, Crypsis schoenoides, Melilotus dentatus, and Plantago maritima grew on the drier and non-inundated soils. Tripolium pannonicum, Spergularia maritima, and Lotus tenuis grew on both wet and dry soils. Trifolium fragiferum and Bolboschoenus maritimus were found in places with water stagnant at the soil level. Pulicaria dysenterica grew in inundated soil.

Grazing reduces bee abundance and diversity in saltmarshes by suppressing flowering of key plant species

Global declines in pollinator populations and associated services make it imperative to identify and sensitively manage valuable habitats. Coastal habitats such as saltmarshes can support extensive flowering meadows, but their importance for pollinators, and how this varies with land-use intensity, is poorly understood. We hypothesised that saltmarshes provide important bee foraging habitat, and that livestock grazing either suppresses or enhances its value by reducing the abundance - or increasing the diversity - of flowering plants. To test these hypotheses, we surveyed 11 saltmarshes in Wales (UK) under varying grazing management (long-term ungrazed, extensively grazed, intensively grazed) over three summers and investigated causal pathways linking grazing intensity with bee abundance and diversity using a series of linear mixed models. We also compared observed bee abundances to 11 common terrestrial habitats using national survey data.Grazing reduced bee abundance and richness via reductions in the flower cover of the two key food plants: sea aster Tripolium pannonicum and sea lavender Limonium spp. Grazing also increased flowering plant richness, but the positive effects of flower richness did not compensate for the negative effects of reduced flower cover on bees. Bee abundances were approximately halved in extensively grazed marshes (relative to ungrazed) and halved again in intensively grazed marshes. Saltmarsh flowers were primarily visited by honeybees Apis mellifera and bumblebees Bombus spp. in mid and late summer. Compared to other broad habitat types in Wales, ungrazed saltmarshes ranked highly for honeybees and bumblebees in July-August, but were relatively unimportant for solitary bees. Intensively grazed saltmarshes were amongst the least valuable habitats for all bee types.Under appropriate grazing management, saltmarshes provide a valuable and previously overlooked foraging habitat for bees. The strong effects of livestock grazing identified here are likely to extend geographically given that both livestock grazing and key grazing-sensitive plants are widespread in European saltmarshes. We recommend that long-term ungrazed saltmarshes are protected from grazing, and that grazing is maintained at extensive levels on grazed marshes. In this way, saltmarshes can provide forage for wild and managed bee populations and support ecosystem services.

Manipulating saltmarsh microtopography modulates the effects of elevation on sediment redox potential and halophyte distribution

Abstract Halophyte distributions on saltmarshes are strongly related to elevation in the tidal frame. However, collinearity between elevation, the consequent inundation regime, and sediment waterlogging/redox potential obscures the proximate causes of distribution patterns. We sought to distinguish the effects of elevation per se from those of waterlogging by manipulating microtopography. We experimentally manipulated elevation by ±15 cm at locations that spanned the elevation ranges of three saltmarshes recently reactivated by managed coastal realignment. Experimental plots were initially cleared of any vegetation. Elevation and sediment redox potential were determined for each plot. We planted five perennial species (Armeria maritima, Atriplex portulacoides, Limonium vulgare, Plantago maritima and Triglochin maritima) in half of the plots, recording survival over 4 years, and monitored natural colonization of the other plots. Overall, redox potential increased with elevation. Sediments were more oxidizing in raised plots and more reducing in lowered plots. Redox reductions in lowered plots were in line with those that would be predicted from the overall redox/elevation relationship, but increases in raised plots were greater than predicted from elevation alone. Plant colonization and survival was poorer in lowered plots and, for most species, improved in raised plots. This poorer colonization and survival can, in part, be attributed to the concomitant alterations in redox potential and elevation in the tidal frame, but microtopographic manipulation also had substantial independent effects on plant performance, including on the survival of all planted species and the colonization of Puccinellia maritima, Salicornia europaea agg. and Tripolium pannonicum. Synthesis. Microtopography can have effects on sediment chemistry and plant performance similar in magnitude to those of overall tidal elevation. Understanding how its effects modulate the relationship between tidal elevation, redox and other environmental conditions helps clarify the abiotic factors that fundamentally determine halophyte colonization and survival. These results support the use of topographic manipulation to enhance the diversity of created saltmarshes.