Introduction
The important precondition for formation of the Fageto-Carpineto-Querceta roboris forest groups is the presence of hilly relief and carbonate soils of alluvial origin [1] . The vegetal cover is closely connected with natural environment that predetermines its coenotic structure and is characterized with multilevel construction. The first tier is formed by Quercus robur L., Fagus sylvatica L. and rarely Picea abies Karst. Fraxinus excelsior L., Acer platanoides L., Tilia cordata Mill are mixed to it. The second tier is formed by Carpinus betulus L. and Fagus sylvatica L. In some places there is the third tier with Carpinus betulus L., Acer campestre L., Malus sylvestris (L.) Mill. and Cerasus avium (L.) Moench. In undergrowth tier grow Corylus avellana L., Euonymus europaеa L., Swida sanguinea L., Frangula alnus Mill., Crataegus monogyna Jacq., C. oxyacantha L., C sanguinea Pall. and C. ucrainica Pojark. At spring before the leaves blooming synsias of the early spring ephemeroids prevail.
Literature survey
Among the modern works on the study of vegetation of the Ukrainian west regions are the works of geobotanical direction written by Gerushinsky Z. Y. (1996) , Nesteruk Y. (2000), Buniak V. I. (2001), Parpan V. I. and the others [2−6] . In these works the important place takes the characteristics and description of the Carpathian and Precarpathian beech forests.
Mixed phytocenoses prevail in the group of formation of beech-hornbeam-oaken forests. Monograph by Lavrinenko D. D. (1965) is rather important for explanation of the complicated interplays between edificators, assectators of the oaken forests. The regional peculiarities of economy in the Carpathian mountain forests are noted in the work by Gensiruk S. A. (2002) . In Zacarpathian foothills on the outcrops of volcanic rocks are spread the insular localizations of anhedral oaken forests and bush formations. Biotopes of the foliage forests were studied by Kish R., Andrik E., Mirutenko V. [7] .
The interesting forest studies concerning Precarpathian beech-hornbeam-oaken forests, its natural renewal and reproduction were described by Katsuliak Y. D. [8] . The recreational value of plain and mountain forests was elucidated by Bondarenko V. D. and Furdychko O. I. (1994) .
In Ivano-frankivsk region are known the groves of Quercus robur L. and Quercus petraea Liebl. The groves of Quercus robur L. are particularly spread in the plain localities with admixture of Carpinus betulus L., Fraxinus excelsior L., Populus tremula L., Betula pendula Roth. On the plain part and on the foothills of region the several localities are occupied by such mixed large-leaved forests as hornbeam-beech and oak-beech. Its floristic and syntaxonomic structure was described in the works of Tkachik V. (2000) and Stojko S. M. [9] [10] [11] . In particular Stojko S. M. elaborated classification of beech-hornbeam-oaken forests of Ukrainian Carpathians [11] . In the work of Chopyk V. I. and Fedoronchuk M. M. [12] was elucidated an ecology, spreading, taxonomic and resource specificity of the specific composition of vascular plants of Ukrainian Carpathians.
The aforesaid botanical and forest publications deal with the results of research of the oaken phytocenoses in separate regions.
In the book by Panova L. S., Protopopova V. V., Morozuk S. S. [13] there were presented the plants of Ukrainian flora that blossom in spring. There were also described biological and ecological peculiarities and spreading of these species. The special attention was paid to the important problem of its protection.
Aim and tasks of research
Aim -the study of ontogenesis of ephemeroids that form the early spring synusias in the forests of Fageto-Carpineto-Querceta roboris subformation in Pricarpathian region.
For attaining the set aim the following tasks must be carried out: -to reveal population of the spread species-ephemeroids that form the early spring synusias; -to study ontogenesis of revealed species; -to study the modern state of population.
Methods and materials of research
The study of the early spring synusias in the forests of Fageto-Carpineto-Querceta roboris subformation was carried out during vegetative period 2000-2003 years and 2014-2016 years by the route method as pave of the profile lines along which were made the temporary test plots for species accounting, was formed the synopsis of flora, was fixed the tiers of phytocenosis, its aspects, the cover density, the species vitality, were studied the conditions of plants growth.
The determination of plants was carried out according to "Determinant of Ukrainian Carpathian plants" (1977) , systematic taxons were taken according to Takhtadjan A. L. (1987), the structure of populations was described according to Grigoroy I. M. and Solomakha V. A. [14] , and the Ramensky's L. G. net was used for determination of species project cover [14] .
Results of research
In the studied subformation prevailed five associations: Fageto-Carpineto-Quercetum roboris galiosum odorati, Fageto-Carpineto-Quercetum roboris caricetum pilosae, Fageto-Carpineto-Quercetum roboris vincosum, Fageto-Carpineto-Quercetum roboris galeobdolosum, Fageto-Carpineto-Quercetum roboris hederosum.
The In February-April the spring aspect is clearly expressed in studied phytocenoses. The herbal early spring synusias of ephemeroid species: Leucojum vernum L., Galanthus nivalis L., Dentaria glandulosa Waldst. et Kit., Anemone nemorosa L., Scilla bifolia L., Isopyrum thalictroides L., Corydalis cava (L.) Schweigg. Koerte та Gagea lutea (L.) Ker.-Gawl astonish by its botanical value and unique beauty [16] . Before the leaves blooming there is observed the early blossom of these species that create the specific white-lilac-blue aspect.
Our As to fruitfulness we did not observe in Galanthus nivalis L. any individual with fruits, despite the abundant blossom it is possible that there are no pollination. And in the Leucojum vernum L. all blossoming shoots bear fruits. It testifies that it is reproduced with onions as well as with seeds.
Scilla bifolia L. cenopopulations from the Liliaceae family is rarely found in forests. It is spread as the small inclusions in 5-6 individuals in every one. The blossom was observed from the second decade of March to the first decade of April.
In the second and third decades of March dominates the early spring ephemeroid from The blossom of these ephemeroids continues during two weeks (April-May) and can take place at the considerable temperature fluctuations. Flowers have a pleasant scent, produce a lot of nectar and are pollinated by insects so the most of generative individuals bear fruits. But to the high regret we did not observe the seeds ripening. Probably because of deficiency of sunshine that cannot penetrate through the developed leaves of trees. It must be noted that side by side with this synusia in several wet places are found the small but unbroken flowerbeds of perennial rhizome plant from the Saxifragaceae -Chrysosplenium alternofolium L. family that also blossoms in the second-third decade of April forming the original golden-yellow aspect. According to our observations cenopopulations of this species are related to the described association.
Approbation of the results of research
The results of research were discussed at annual scientific-practical conferences of the teachers of Institute of natural sciences of SHEI "Vasyl Stefanyk Precarpathian National University".
Conclusions
Our researches demonstrated that the Fageto-Carpineto-Querceta roboris forest associations have the rich and botanically significant specific composition especially the early spring synusias formed by the rare decorative ephemeroids species astonish by its beauty and originality. In the summer aspect of association were also revealed the species of plants put to the Ukrainian red book (Cephalanthera damasonium (Mill.) Druce, C. longifolia (L.) Fritsch., Cypripedium calceolus (L.) and elements of thermophilic forest-steppe flora (Vincetocsicum hirundinaria Medik., Pyrethrum corymbosum (L.) Scop., Sedum hispanicum L.) that are rarely found on Precarpathian territory.
The study of specific composition and spread of cenopopulations of early spring synusias demonstrated that its number significantly decreased in last decades and the group of such Red book species as Leucojum vernum L. and Galanthus nivalis L. absolutely disappeared in several Precarpathian forest tracts. There remains only the spring phytocenoses with dominating Anemone nemorosa L. and Scilla bifolia L.
For protection and reproduction of the early spring ephemeroids on the studied territory must be organized monitoring on ontogenesis and state of its populations, it is necessary to study the biological and ecological peculiarities, number of individuals and the frequency of occurrence in cenoses.

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