The aim of the research was to study the floristic richness of balks, i.e. uncultivated strips separating fields, and to research the dependence of plant communities there on habitat conditions and adjacent crops. The share of segetal species in those communities was also analysed. In the western part of the Siedlce Plateau 70 balks among intensively cultivated fields were examined in 2016–2018. The balks divided fields with corn, winter cereals and spring cereal mixtures. The research was conducted with the Braun-Blanquet method, with 110 phytosociological relevés results used as study material. The flora specified this way was analysed in terms of biological structure, forms of life, persistence, historical and geographical spectrum, species rarity and presence of invasive species. In addition, the interdependence between the species richness of balks and habitat conditions as well as the type of neighbouring crops was studied. Habitat conditions were established with the Ellenberg indicator values, based on indicative species and taking into account light, temperature, moisture, soil reaction and nitrogen content. The development and floristic diversity of balk plant communities as ecotone areas were largely influenced by a proximity of arable fields and habitat conditions, especially by soil moisture and the amount of nitrogen. Balk flora consisted of vascular plants with 161 species, mainly apophytes. Those were mostly perennial species, hemikryptophytes. Among the most common field weeds from the class of Stellarietea mediae, 25 species were identified in balks. There were 26 rare and endangered species and 14 species having the status of invasive taxa.
Habitat fragmentation is one of serious threats to biodiversity of nature in today's world. The present study of a typical steppe species Iris pumila L. (Iridaceae) has analyzed the impacts of geographical isolation and population size on genetic diversity and population structure in conditions of habitat fragmentation. The key indices of population genetic variability calculated from the ISSR markers data were on average as follows: Shannon diversity index (S) – 0.188; unbiased Nei’s gene diversity (He) – 0.123; and the average measure of Jaccard’s genetic distances between individuals within populations – 58.4%. Although the largest population had significantly higher values of S and He, the small and marginal populations also showed a comparable level of variation. Most of the genetic variation of I. pumila was distributed within the populations. A strong correlation was found between Nei’s genetic distances and geographic distances between the populations. According to the Bayesian analysis, genetic structure of the populations was highly homogeneous; however, the presence of admixed genotypes indicated the possibility of gene flow between the populations at present.
The avifaunistic observations carried out in the tundra valley of the Sob River's upper course (west slopes of the Polar Ural) in July 1995 revealed the occurrence of 39 breeding and 8 non-breeding bird species. The most numerous were Anthus pratensis, Calcarius lapponicus, Phylloscopus trochilus and Anthus cervinus. The great variety of wetland and aquatic habitats had a decisive influence on species-richness and abundance of birds (jointly 30 breeding and 4 non-breeding species). Areas of low humidity were inhabited by 14 whereas anthropogenic habitats by 4 species. Most of them (except for eurytopic A. pratensis and C. lapponicus) occupied one-two habitats irrespective of their numbers. The density of Buteo lagopus was estimated at 1.67-2.00 p/10 km2. Three species of distribution ranges laying to the south from the study area, namely Bucephala clangula, Dendrocopos major, Circus macrourus, were noted in the valley. The results obtained have been compared with available data on the avifauna of the region concerned.
There is a cascade of hydroelectric power plants built on the Váh River. From a water-management point of view, the natural channel is used to drain extreme discharges. During most of the year, discharges are regulated by water-management structures. These discharges are not used for energy-related purposes; therefore, it is important to determine the optimal discharge that will not negatively affect the ecosystem of the stream. The minimum balance discharge (hydro-ecological discharge) was determined based on the instream flow incremental methodology (IFIM) using the riverine habi-tat simulation system (RHABSIM). Input data were obtained from direct measurements on three reference reaches in the area between the cities Piešťany and Nové Mesto nad Váhom. Hydraulic flow characteristics were derived from three measurements at different water levels. Habitat quality was represented by ichthyofauna. Data to determine the habitat suit-ability curves of fish were obtained using a diving technique to collect video footage. The modelling resulted in the quanti-fication of the effect of discharge on ichthyofauna as a bio-indicator of habitat quality, which implied the need of 20 m3∙s–1 for a minimum balance discharge in summer.