69 road sections with amphibian mortality known from 2006 in Lviv Region (Western Ukraine) were repeatedly surveyed in 2017. 2078 dead individuals of nine amphibian species were detected and identified on the road surface (Triturus cristatus, Bombina bombina, Pelobates fuscus, Bufo bufo, Hyla orientalis, Rana temporaria, Rana arvalis, Pelophylax ridibundus and Pelophylax esculentus). The most numerous victims appeared to be B. bufo (72.8 %) and R. temporaria (22.6 %) which is almost the same as in 2006 (90.5 % together). However, the qualitative and quantitative composition has decreased in a decade (compare 3555 individuals of 13 amphibian species in 2006). As we suppose, the main reasons for amphibian population decline in the region are contamination, degradation and disappearance of the breeding ponds as well as the increased traffic intensity. According to the estimation of our research four B. bufo populations are under the excessive influence of roads and transportation, and need to be protected. One of these road sections was fenced up by temporary amphibian fences during the breeding migration (April 2018). Amphibian mortality on the fenced road section dropped down instantly: over thousand individuals of B. bufo and R. temporaria were caught alive into the bucket-traps and safely moved across the road.

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on-line) • Біологічні Студії / Studia Biologica • 2019 • Том 13/№1 • С. 161-168 Moor frog Rana arvalis, Spadefoot Pelobates fuscus, Green toad Bufotes viridis etc. are worthy of notice as the indicators of environment (habitat) status.The attention is drawn to the consortive analysis as the most effective instrument in the research of interrelations between key species and biodiversity. The analysis is focused on the research of obligate and facultative organisms of different taxonomic groups which are functioning as a whole.

The attention in the article is paid to the key species research importance. Their classification was discussed in our article published in “Studia Biologica” (Y. Tsaryk, O. Reshetylo, I. Tsaryk, Biol. Stud. 2019: 13(1); 161–168). The main emphasis was made on ecological key species, while other categories were analyzed as well (protective, social etc.). A row of potential key species in different ecosystems was proposed based on the original field research. So, such phytophagous insects like the alder leaf beetles Agelastica alni, Linaeidea aenea, and the mother of pearl moth Patania ruralis are proposed to be the key species in forest ecosystems. Altogether in terrestrial ecosystems such species as the common carder bee Bombus pascuorum and the buff-tailed bumblebee B. terrestris are tend to be the key species among the pollinators (excluding European honey bee Apis mellifera). Ants are important invertebrate key species as well: Formica – in forest ecosystems, Lasius, Myrmica and Tetramorium – shrub and meadow ones. Almost the same we can say about some species of amphibians (the common toad Bufo bufo, the common frog Rana temporaria, and the edible frog Pelophylax esculentus). Eurasian jay Garrulus glandarius, the great tit Parus major, and woodpeckers, the great spotted woodpecker Dendrocopos major in particular, are among the birds’ key species on our minds. European otter Lutra lutra is the possible key species in freshwater ecosystems. Zooplankton as a whole community might be considered a key “species” too. The great pond snail Lymnaea stagnalis is the key species among freshwater mollusks. The fish of Barbatula, Cobitis, Sabanejewia, Misgurnus genera, and Eudontomyzon representatives are the key species in streams and rivers. European beaver Castor fiber, European otter L. lutra, the white stork Ciconia ciconia, and reed warblers are thought to be the key species in semiaquatic ecosystems. The presented data about the key species need further research on their population and consortive organizations, as well as their functional role in the support of ecosystem stability under the environmental stochasticity, has to be clarified.

Introduction. Due to a significant biomass and diverse ecological niches, ants (Formicidae, Hymenoptera) are crucial in establishing the structure and functioning of the co-adaptive species complexes, i.e. myrmecocomplexes, to which they belong. The majority of ant species, which build their nests with visible anthills, create humpy micro-relief changing the habitats of numerous plant and animal species. The number of active ant families and the number of their nests indicate the functional power of every species in an ant community. According to the dynamics of nest numbers, it is possible to analyze the changes in the ecosystem as a whole. Materials and methods. The research territory is located in the SE suburb of Lviv on the edge of Davydiv and Holohory ridges. It includes two former agricultural sites: fallow arable land and fallow grazing land. The material was collected by the method of ant exclusion with its following conservation, laboratory analysis and determination. Anthill mapping was conducted on 200 sq. m sites. Results and discussion. The results suggest that the more structured a habitat is, the higher ant species diversity is observed: seven species were found in the fallow grazing land (Formica pratensis – dominant, F. cunicularia – subdominant, Tetramorium caespitum, Lasius niger, L. flavus, Myrmica rubra, Solenopsis fugax – all are influents). It is typical of the three influent species (L. flavus, T. caespitum, M. rubra) to distribute within the territory of a dominant’s foraging area. However, the influent ant species avoid contacting each other. The less structured habitat (fallow arable land) is presented by only two of the most adaptive species, which are in high numbers (L. niger – 95 % of the site nests, and L. flavus – only 5 % of them). Conclusions. Thus, each ant community is a system of „dominant–subdominant–influent” species, which is under permanent transformation due to anthropogenic habitat changes; only well-adapted species can stay in the community under the influence of the mentioned changes. The research on the spatial distribution of ant nests testifies to the prospects and need for the mapping method used to establish the type and level of previous anthropogenic impact on the ecosystem (grazing, ploughing, grass burning, etc.).