Ruzica Igic

A higher‐level classification of the Pannonian and western Pontic steppe grasslands (Central and Eastern Europe)

Abstract Questions What are the main floristic patterns in the Pannonian and western Pontic steppe grasslands? What are the diagnostic species of the major subdivisions of the class Festuco‐Brometea (temperate Euro‐Siberian dry and semi‐dry grasslands)? Location Carpathian Basin (E Austria, SE Czech Republic, Slovakia, Hungary, Romania, Slovenia, N Croatia and N Serbia), Ukraine, S Poland and the Bryansk region of W Russia. Methods We applied a geographically stratified resampling to a large set of relevés containing at least one indicator species of steppe grasslands. The resulting data set of 17 993 relevés was classified using the TWINSPAN algorithm. We identified groups of clusters that corresponded to the class Festuco‐Brometea. After excluding relevés not belonging to our target class, we applied a consensus of three fidelity measures, also taking into account external knowledge, to establish the diagnostic species of the orders of the class. The original TWINSPAN divisions were revised on the basis of these diagnostic species. Results The TWINSPAN classification revealed soil moisture as the most important environmental factor. Eight out of 16 TWINSPAN groups corresponded to Festuco‐Brometea. A total of 80, 32 and 58 species were accepted as diagnostic for the orders Brometalia erecti, Festucetalia valesiacae and Stipo‐Festucetalia pallentis, respectively. In the further subdivision of the orders, soil conditions, geographic distribution and altitude could be identified as factors driving the major floristic patterns. Conclusions We propose the following classification of the Festuco‐Brometea in our study area: (1) Brometalia erecti (semi‐dry grasslands) with Scabioso ochroleucae‐Poion angustifoliae (steppe meadows of the forest zone of E Europe) and Cirsio‐Brachypodion pinnati (meadow steppes on deep soils in the forest‐steppe zone of E Central and E Europe); (2) Festucetalia valesiacae (grass steppes) with Festucion valesiacae (grass steppes on less developed soils in the forest‐steppe zone of E Central and E Europe) and Stipion lessingianae (grass steppes in the steppe zone); (3) Stipo‐Festucetalia pallentis (rocky steppes) with Asplenio septentrionalis‐Festucion pallentis (rocky steppes on siliceous and intermediate soils), Bromo‐Festucion pallentis (thermophilous rocky steppes on calcareous soils), Diantho‐Seslerion (dealpine Sesleria caerulea grasslands of the Western Carpathians) and Seslerion rigidae (dealpine Sesleria rigida grasslands of the Romanian Carpathians).

Variability of Content and Composition of Mentha aquatica L. (Lamiaceae) Essential Oil in Different Phenophases

Abstract The content and chemical composition of Mentha aquatica L. (Lamiaceae) essential oil during three phenophases (before flowering, flowering and after flowering) was compared. Quantities of the essential oils were determined according to the European Pharmacopoeia 4ed 12 and chemical profiles by GC-MS. The highest content of the essential oil was found before flowering stage (0.73%). The main constituent of the essential oil through all the three phenophases was menthofuran (19.0–24.5%), followed by 1,8-cineole (11.8–20.2%), E-caryophyllene (6.7–16.6%) and viridiflorol (7.6–9.0%). Although the composition of the essential oil in all the three investigated phenophases was generaly similar, some qualitative differences were observed (presence of α-guaiene, γ-murolene, valencene and germacrene B only before flowering, linalool and pulegone in the flowering stage, and α-thujene, geranyl acetate, α-bisabolol oxide and 1-octene-3-ol acetate after flowering). Furthermore, the differences in quantities of all compounds present in the essential oils were also recorded. However, the qualitative composition of main constituents of the essential oil in all the three investigated stages led to the suggestion that the menthofuran, as the major compound could be used as the stable chemosystematic marker in the Mentha aquatica L. taxonomy.

The relationship between habitat factors and aquatic macrophyte assemblages in the Danube river in Serbia

Our objectives were to offer insight into the characteristics of the physical environment in the River Danube in Serbia; and to show the relationship between selected environmental factors and the composition and abundance of macrophyte species. The macrophyte survey method followed the European Standard EN 14184, applying Kohler’s five-level descriptive scale. Principal component analysis was carried out to examine the variation in aquatic vegetation, and to analyze the effect of environmental variables on the aquatic vegetation, redundancy analysis was used. To build a simpler model with fewer explanatory variables, yet sufficiently explaining species variability, forward selection of environmental variables was done. Our results confirmed that physical environmental factors significantly influence the establishment and structure of macrophyte vegetation, with the level of hydrological connectivity to the main river channel being the most important, followed by the transparency of the water column, sediment texture and water-flow velocity. In order to inspect the individual relation between best-fitted plant species and each of selected environmental variables, Spearman’s rank correlation coefficients were calculated. We have distinguished plant species with preferences to specific combinations of analyzed factors. Our results provide a background for future, more specific studies on the macrophyte/habitat relationship. https://doi.org/10.2298/ABS160516116V Received: May 16, 2016; Accepted: June 21, 2016; Published online: October 31, 2016 How to cite: Vukov D, Ilic M, Cuk M, Igic R, Janauer GA. The relationship between habitat factors and aquatic macrophyte assemblages in the Danube river in Serbia. Arch Biol Sci. 2017;69(3):427-37.