Jozef Kollár

Recent Plant Diversity Changes on Europe’s Mountain Summits

Climb Every Mountain Mountaintop floras across Europe appear to be responding to climatic change in terms of upslope species range shifts. Pauli et al. (p. 353) systematically analyzed data gathered from standardized permanent plots on 66 high-mountain environments across Europe. On average, mountaintop species numbers have increased significantly during the last decade. However, this increase is a net effect of gains and losses, with losses particularly affecting mountains of Mediterranean regions and their endemic species. This turnover is largely consistent with model predictions and indicates that high-altitude species, and in particular the rich endemic alpine flora of many Mediterranean mountain ranges, will come under increasing pressure in the predicted warmer and drier climates in this region. European mountaintop flower species richness is increasing on northern summits but decreasing on southern summits. In mountainous regions, climate warming is expected to shift species’ ranges to higher altitudes. Evidence for such shifts is still mostly from revisitations of historical sites. We present recent (2001 to 2008) changes in vascular plant species richness observed in a standardized monitoring network across Europe’s major mountain ranges. Species have moved upslope on average. However, these shifts had opposite effects on the summit floras’ species richness in boreal-temperate mountain regions (+3.9 species on average) and Mediterranean mountain regions (–1.4 species), probably because recent climatic trends have decreased the availability of water in the European south. Because Mediterranean mountains are particularly rich in endemic species, a continuation of these trends might shrink the European mountain flora, despite an average increase in summit species richness across the region.

Pines influence hydrophysical parameters and water flow in a sandy soil

Pines, used for sand dune stabilization, can influence the hydrophysical parameters and water flow in an aeolian sandy soil considerably, mainly due to soil water repellency. Two sites, separated by distance of about 20 m, formed the basis of our study. A control soil (“Pure sand“) with limited impact of vegetation or organic matter was formed at 50 cm depth beneath a forest glade area. This was compared to a “Forest soil” in a 30-year old Scots pine (Pinus sylvestris) forest. Most of the hydrophysical parameters were substantially different between the two soil surfaces. The forest soil was substantially more water repellent and had two-times the degree of preferential flow compared to pure sand. Water and ethanol sorptivities, hydraulic conductivity, and saturated hydraulic conductivity were 1%, 84%, 2% and 26% those of the pure sand, respectively. The change in soil hydrophysical parameters due to soil water repellency resulted in preferential flow in the forest soil, emerging during a simulated heavy rain following a long hot, dry period. The wetting front established in pure sand exhibited a form typical of that for stable flow. Such a shape of the wetting front can be expected in the forest soil in spring, when soil water repellency is alleviated substantially.

Experience with using Ellenberg’s R indicator values in Slovakia: Oligotrophic and mesotrophic submontane broad-leaved forests

Ellenberg’s indicator values have been suggested as useful method of estimating site conditions using plants. We examined whether Ellenberg’s R values are suitable for indicating soil reaction and if calibration to physical pH measurements can improve bioindication in oligotrophic and mesotrophic submontane broad-leaved forests in Slovakia. Vegetation relevés and pH-H2O and pH-CaCl2 soil reaction were recorded for this purpose. Ellenberg’s R values (Re) were compared to Jurko’s indicator values (Rj) and a set of species R values and tolerances (T), which were calibrated with physical pH data using the weighted averaging (Rw, Tw) and Huisman-Olff-Fresco modelling (Rh, Th). Original Re values were then recalibrated with measured pH data to establish new, adjusted set of scores (Rc, Tc) at Ellenberg’s scale. The Re values are significantly correlated with the other R values, and they demonstrate similar frequency distribution to Rj and Rw values for the studied species pool. The frequency distribution becomes similar across all the R values when indifferent species were excluded. The performance of all the indicator values in terms of bioindication was tested. Relevé means of the R values were regressed on the field pH measurements. The performance of bioindication varied from 36% to 49% of the explained variance for pH-CaCl2, with the Re and Rc values yielding 46% and 49% respectively. The bioindication slightly improved for all calibrated methods (Rw, Rh and Rc) when species were weighted inversely with their tolerances — the performance varied from 42% to 51%, and the Rc values performed most effectively. We concluded that Ellenberg’s R values represent a powerful system for bioindicating soil acidity when compared to the other alternatives, with pH-CaCl2 showing better results than pH-H2O. Recalibration of Ellenberg’s values to the measured data improved the indicator system.

Effects of vegetation at different succession stages on soil properties and water flow in sandy soil

Abstract The effects of vegetation at different succession stages on soil properties and water flow were assessed in sandy soil at 3 experimental sites near Sekule village (southwest Slovakia). Site S1 was a pioneer site dominated by mosses, site S2 was an early successional stage with a thin stand of grasses, and site S3 was an early successional stage (more advanced compared to the previous), richer in species, with a denser stand of grasses. It was found that vegetation at different succession stages affected soil properties and water flow in sandy soil, but the order of changes in some soil properties and water penetration depths were different from the order of succession stages.

Indicating Soil Acidity Using Vegetation Relevés in Spatially Limited Areas - Case Study from the Považský Inovec, Slovakia

A fine-scaled approach for predicting soil acidity using plant species in a spatially limited area (Čepúšky Nature Reserve, Slovakia) is presented here. This approach copes with some specific limitations: i) a limited pool of vegetation data may make the predictions too sensitive to the lack of species information, and ii) the predictions may be sensitive to the narrow pH gradient. Vegetation relevés and soil reaction (pH-H2O and pH-CaCl2) were systematically recorded. A set of species indicator values and amplitudes was calibrated with physical pH data using the Weighted Averaging (WA), HOF modelling and Non-Metric Multidimensional Scaling (NMDS) methods, along with Ellenberg indicator values. Two prediction methods were tested: i) WA and ii) Amplitude Overlap (AO). WA prediction with Ellenberg’s and WA-calibrated species indicator values were the most powerful technique (R2 = 68.4–68.7% and 53.4–59.1% for pH-CaCl2 and pH-H2O, respectively). WA-prediction with HOF-based indicator values was less effective (R2 = 61.7% and 50.7%) due to the decrease in species’ information because with HOF modelling many species are assumed indifferent or too rare. The NMDS method does not bring any significant gain to the calibration, though it avoids the lack of species information. The AO method was proven to be less powerful under studied circumstances, because it is sensitive both to the lack of species’ information and to the truncation of species responses. The results prove that a spatially explicit approach can provide significant indices to estimate changes in soil acidity – pH-CaCl2 better than pH-H2O.

Preparation and Photophysics of 2-(1-Pyrenyl)acrylic Acid and Its Methyl and 2′,2′,6′,6′-Tetramethyl-4′-Piperidyl Esters

Novel probes represented connection of pyrene as chromophore and sterically hindered amine stabilizers (HAS) in the form of esters of 2-(1-pyrenyl)acrylic acid were synthesized. HAS was in the form of parent amine (PAP) as well as stable nitroxyl radical form (PAP-NO.). Photophysics of these probes were compared with their precursor as 2-(1-pyrenyl)acrylic acid (PAA) and its methyl ester (PAM). The fluorescence spectrum of PAA strongly depends on the acidity of the solution. The spectrum in neutral methanol indicates that it originates from the anionic form –COO−. Changes of acidity or basicity of methanol solution resulted in the changes of shape, position as well as the intensity of fluorescence band. This is due to the presence of protolytic equilibria, either in the ground state or in the singlet excited state, leading to the formation of molecular form –COOH and the cationic form –COOH2+. The ester analogues did not show any changes in various pH conditions. Fluorescence of all probes depends on the polarity of solvents and the presence of oxygen. Intermolecular quenching was studied with external quenchers TEMPO and oxygen and the data were compared with the intramolecular quenching using 1′-oxo-2′,2′,6′,6′-tetramethyl-4′-piperidinyl-2-(1-pyrenyl)acrylate (PAP-NO.).

Modulation of wettability, gradient and adhesion on self-assembled monolayer by counterion exchange and pH

In this study, two quaternary ammonium salts derived from l-lipoic acid were applied for self-assembled monolayers formation on rough structured gold surface. The derivatives differ in functionality since one possesses simple quaternary ammonium group whereas the other one is carboxybetaine ester containing quaternary ammonium group with pH hydrolysable ester group as a pendant. The response of surface wettability to ion exchange between Cl- and perfluorooctanoate, kinetics and gradient wettability were examined by water contact angle measurement and confirmed by X-ray photoelectron spectroscopy. Furthermore, adhesion forces related to applied counterion on the entire surface and after hydrolysis were investigated by atomic force microscopy measurement at nanometer scales. A dramatic change in wettability upon counterion exchange from superhydrophilic for Cl- to very or superhydrophobic for perfluorooctanoate in a repeatable manner was observed for both derivatives. Kinetics of counterion exchanges revealed faster hydration of simple quaternary derivate. The wettability gradient could be designed from superhydrophobic to superhydrophilic either in a reversible manner by simple immersion of the modified surface in a counterion solution modulated by ionic strength or in an irreversible manner for carboxybetaine ester derivate by time-controlled hydrolysis to charge balanced carboxybetaine.

pH-switchable interaction of a carboxybetaine ester-based SAM with DNA and gold nanoparticles

We describe a self-assembled monolayer (SAM) on a gold surface with a carboxybetaine ester functionality to control the interaction between DNA and gold nanoparticles via pH. The negatively charged phosphate backbone of DNA interacts with and adsorbs to the positively charged carboxybetaine esters on the SAM. DNA release can be achieved by the hydrolysis of carboxybetaine ester (CBE) to a zwitterionic carboxybetaine state. Furthermore, the adsorption of negatively charged citrate-capped gold nanoparticles to a SAM-modified plain gold surface can be controlled by the pH. The SAM based on carboxybetaine ester allows for the homogeneous adsorption of particles, whereas the SAM after hydrolysis at high pH repels AuNP adsorption. The antifouling surface properties of the surface modified with carboxybetaine were investigated with protein samples.

Superabsorbent hydrogels made from bio-sourced butyrolactone monomer in aqueous solution

A new water-soluble monomer, sodium 4-hydroxy-4-methyl-2-methylene butanoate (SHMeMB), formed by saponification of the bio-derived monomer γ-methyl-α-methylene-γ-butyrolactone (MeMBL), was copolymerized with acrylamide (AM) in aqueous solution to make superabsorbent hydrogels with equilibrium degree of swelling in the range of 6700–59 000%, depending on monomer ratio and crosslink density. Mechanical strength and storage and loss moduli of the hydrogels were tunable over a wide range through adjustment of the comonomer composition and the crosslinker content. Monomer reactivity ratios of rSHMeMB = 0.12–0.17 and rAM = 0.95–1.10 were determined using copolymer compositions measured at low monomer conversion as well as by applying the integrated form of the Mayo-Lewis equation to fit the drift in comonomer composition with conversion. The reactivity of the SHMeMB : AM system was lower than that of the previously-studied SHMB : AM system, with sodium 4-hydroxy-2-methylene butanoate (SHMB) derived from a similar renewable monomer, α-methylene-γ-butyrolactone (MBL). The differences in reactivity were studied by pulsed laser polymerization coupled with size exclusion chromatography; the comonomer-averaged propagation rate coefficient of the SHMB : AM system was found to be more than double that of SHMeMB : AM, with first estimates for the SHMeMB and SHMB homopropagation rate coefficients of 25 and 165 L mol−1 s−1, respectively, at 60 °C. Despite its lower reactivity, SHMeMB offers advantages over SHMB due to its availability and as superior overall properties of the final hydrogels were achieved.

Effect of vegetation and its succession on water repellency in sandy soils: Effect of vegetation and its succession on soil water repellency

1 Institute of Hydrology, Slovak Academy of Sciences, Bratislava, Slovak Republic Department of Soil Science, Faculty of Organic Agricultural Sciences, University of Kassel, Witzenhausen, Germany Department of Plant Ecology & Systematics, Faculty of Biology, University of Kaiserslautern, Kaiserslautern, Germany Working Group “Hydropedology,” Research Area 1 “Landscape Functioning”, Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany 5 Institute of Landscape Ecology, Slovak Academy of Sciences, Bratislava, Slovak Republic Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Martonvásár, Hungary Correspondence Lubomir Lichner, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovak Republic. Email: lichner@uh.savba.sk