Igor Zelnik

Wet meadows of the alliance Molinion and their environmental gradients in Slovenia

The main objective of this study was to examine the relationships between wet meadow plant communities of Molinon alliance and their environmental conditions in Slovenia. The ecology of these communities was analysed in detail. The study provides the data on the vegetation and environmental parameters, the significance of parameters for the plant species composition, most important environmental gradients and differences between plant communities. In all plots the vegetation was recorded and soil parameters were analysed (pH, plant-available P and K, Nt, organic C, C/N ratio, exchangeable Ca2+, Mg2+, K+, Na+, H+, electrical conductivity, base saturation). Other conditions were also considered (e.g., mean annual temperature and precipitation, humidity index, mean Ellenberg moisture and nutrient value) to test possible correlations as well. Vegetation was classified by means of multivariate cluster analysis, while vegetation-site relationships were examined with direct gradient analysis (CCA). Six associations from the Molinon alliance (Selino-Molinietum, Plantagini altissimae-Molinietum, Carici davallianae-Molinietum, Gentiano-Molinietum litoralis, Junco conglomerati-Betonicetum and Sanguisorbo-Festucetum commutatae) were identified and analysed. Soil reaction was identified as most significant environmental parameter explaining the variation of the studied vegetation. There are several statistically significant differences in site conditions between the communities (pH, moisture, nutrient status, Ca2+). The studied associations represent clearly defined ecological units.

Plant species diversity and composition of wet grasslands in relation to environmental factors

Relationships between environmental factors and plant species-richness as well as the composition of plant species in wet grasslands from the order Molinietaliacaeruleae were studied with a view to quantifying the relative contribution of different abiotic factors, such as soil chemical parameters, climatic conditions and human impact to diversity of vascular plants and floristic composition. Data and soil samples were collected from 88 plots across Slovenia from regions at the eastern edge of the Po plain, karstic and pre-Alpine mountain regions and the western part of the Pannonian plain, which are classified to sub-Mediterranean, Dinnaric, pre-Alpine and sub-Pannonian phytogeographic areas. Plant diversity was positively correlated with the content of exchangeable Ca2+ in soil and the amount of annual precipitation, while significant negative correlation was calculated in case of the plant-available phosphorous content and altitude. Moreover, plant species richness was also negatively correlated with altitude. Among the groups of environmental factors the group of soil factors revealed the strongest correlation with species richness, followed by climatic and topographic group. The order of these groups was the same in the explanation of species composition. Variance of plant species composition was best explained with altitude, soil pH, geographical gradient, frequency of flooding, mean annual temperature, date of mowing, humidity, annual amount of precipitation as well as with the content of plant-available phosphorous, total nitrogen, exchangeable Mg2+ and Ca2+ in the soil.

Selenium uptake and Se compounds in Se-treated buckwheat

Abstract In field experiments, tartary buckwheat and hybrid buckwheat were foliarly sprayed with an aqueous solution of sodium selenate (20 mg Se L-1). In treated plants, the selenium content was significantly higher than in controls, irrespective of the plant part and taxon of buckwheat. The highest average Se concentrations in hybrid and tartary buckwheat were found in seeds. The main Se species found in seeds was Semethionine. Selenium-sprayed plants had higher photochemical efficiency of photosystem II in both taxa and higher electron transport system activity in hybrid buckwheat, suggesting a positive effect of Se on physiological characteristics. Because of the concentration of Se in both buckwheat taxa and selenomethionine as the dominant species of Se, Se-enriched buckwheat is a potential source of dietary Se for animals and humans.

Do Reflectance Spectra of Different Plant Stands in Wetland Indicate Species Properties

This contribution discusses the relationships between reflectance spectra obtained by field spectroscopy and properties of the leaves of the species that form a stand and the relation between reflectance spectra and stand characteristics. We thus investigate the reliability of conclusions made at the species levels on the basis of the reflectance spectra of the stands. We studied monospecific and mixed stands that thrive in habitats along a hydrological gradient in the intermittent Lake Cerknica. The reflectance spectra differed significantly at the stand and leaf levels; however, although the shape of the reflectance spectra of a monospecific stand with Phalaris arundinacea was similar to the shape of the leaf spectra, this was not the case for mixed stands. The leaf morphological and biochemical properties that explain most of the variability of the spectra differed for graminoids and different dicotyledons. This study shows that based on the reflectance spectra, the species properties for monospecific stands can be deduced, while for mixed stands, such deductions can be misleading.

The influence of selected factors on the distribution of epilithic diatoms in a torrential river the Kamniška Bistrica (Slovenia)

Abstract Physical and chemical characteristics of habitats and species diversity in streams and rivers are strongly influenced by the catchment area. We analysed the influence of selected environmental and spatial variables on the diversity and species composition of epilithic diatom communities in periphyton. Samples were collected along the river course in a torrential river the Kamniška Bistrica. Sampling sites were selected in reaches distributed from the source to the outlet of the river and were under different influences from the catchment area and with different physical and chemical characteristics. The most common and dominant diatom species in the periphyton community were Achnan-thes biasolettiana and A. minutissima. Achnanthes species often inhabit rivers and springs with moderate organic pollution. Another common diatom taxon was Gomphonema pumi-lum - a key species indicating oligosaprobic conditions. The results of the canonical cor-respondence analyses revealed that variance of the periphytic diatom community was explained by water temperature and conductivity as well as altitude. Diatom species richness was positively correlated with saprobic index values and abundance of filamentous algae in the river bed indicating a relatively low organic matter and nutrient input into the river system.

Litter-Raking Forests in Se Slovenia and In Croatia

Litter-Raking Forests in Se Slovenia and In Croatia The standard Braun-Blanquet method was used for sampling litter-raking vegetation in southeastern Slovenia (Suha krajina, Bela krajina, Kočevsko) and in the border region in Croatia. Relevés were classified with the TWINSPAN program and two associations were separated: Pteridio-Betuletum Trinajstić et Šugar ex Rauš et Matić 1994 and Molinio-Quercetum Šugar 1972. Both communities are the result of intensive litter collecting (and other human impacts). The first one thrives on carbonate bedrock, while the second is limited on silicate bedrock, as is reflected in its specific floristic composition. Due to abandonment of litter collecting these stands are in progressive successional development, and typical variants are becoming rare and endangered. S standardno Braun-Blanquetovo metodo smo vzorčili steljniško vegetacijo vjugovzhodni Sloveniji (Suha krajina, Bela krajina, Kočevsko) in na mejnem območju s Hrvaško. Popisno gradivo smo klasificirali s programom TWINSPAN in ločili dve asociaciji: Pteridio-Betuletum Trinajstić et Šugar ex Rauš et Matić 1994 in Molinio-Quercetum Šugar 1972. Obe združbi sta nastali zaradi intenzivnega steljarjenja. Prva uspeva na karbonatni podlagi, druga je vezana na silikatne kamnine, kar se odraža v floristični sestavi. Zaradi opuščanja steljarjenja sta obe združbi podvrženi progresivnemu sukcesijskemu razvoju in sta v tipični obliki vedno bolj redki in ogroženi.

Vulnerability of a riparian zone towards invasion by alien plants depends on its structure

Abstract Riparian zones support high biodiversity and are among the most vulnerable parts of the landscape. Their degradation facilitates the spread of invasive alien plant species. Our aim was to investigate the relationship between environmental characteristics of riparian zones and distribution and abundance of invasive alien plant taxa (IAT) along three rivers in Slovenia. In 100-m reaches of riparian zone we determined environmental characteristics and the presence and abundance of IAT. Canonical correspondence analysis was used to assess the relationship between IAT and environmental factors. The numbers and abundances of IAT in specific reaches were correlated with environmental factors using Spearman coefficient. These results revealed that the number and abundance of IAT in riparian zone were strongly positively correlated to the distance from river source, while they were negatively correlated with altitude, vegetation structure complexity, completeness of riparian zone and current velocity. Environmental factors that explained the distribution and abundance of IAT significantly were: the altitude, flow dynamics, distance from source, width of riparian zone, land-use, bank and channel structure, water depth and velocity. The research has pointed out the need for proper management of riparian zones to prevent invasion by IAT and also to strengthen other services provided by riparian zone as buffering anthropogenic impacts to water body, stabilising bank structure and increasing biodiversity.