According to the goals and objectives of the Global Strategy for Plant Conservation for 2011–2020 studying and monitoring the rare component of regional floras is highly relevant. This article presents the results of a nature conservation study of the flora of the Desna Plateau (Кrolevets’ and Hlukhiv geobotanic region), situated in the northeast part of Ukraine at the border line of two geomorphological regions (the Central Russian Upland and the Polesia-Dnipro lowland) and of two physical-geographical zones (Novhorod-Sivers`ke Polesia and the Sums`ky forest-steppe. In the orographic aspect, the territory is made up of the western spurs of the Central Russian Upland with the dissectioned forms of the relief. The studied area consists of about 4000 km2. Field route studies aimed at compiling floral lists, geobotanical description and herbarizing were conducted in the period 2002–2016. Separate sites of nature conservation interest were re-examined in different seasonal periods. The basis of the annotated summary of the rare species of vascular plant flora is made up by the materials of original research, as well as herbarium (KW) and literary reviews. The complex floristic analysis of the rare component of the regional flora was carried out in cameral conditions, which made it possible to identify the systematic, geographical, ecological, phytocenological and nature conservation structures of the rare species of vascular plant flora in the investigated area. According to the data received, the total number of species of vascular plants endangered by anthropogenic impact is composed of 85 species belonging to 32 families, 54 genera. Among the families, the following predominate: Orchidaceae (14 genera), Asteraceae, Ranunculaceae (8 genera in each), Iridaceae (5), Aspidiaceae, Cyperaceae (4 genera in each). Among the genera, the following predominate – Carex (4 species); Dryopteris, Orchis, Iris, Jurinea – 3 species in each. It was concluded that among the rare species there are plant species of different physical and geographical zones and this corresponds to the ecotone location of the region. Among species at the edge of their range, 14 are on the extreme northern border of their typical range (Linum flavum L., Carex rhizina Blytt ex Lindb., Centaurea ruthenica Lam., Trinia multicaulis Schishk, Aster amellus L., Galatella linosyris (L.) Rchb. f., Stipa tirsa Steven), 7 species are found on the southern border of their range (Cypripedium calceolus L., Pedicularis sceptrum-carolinum L., Parnassia palustris L., Lycopodium annotinum L., 4 species (Anemone nemorosa L., Salix myrsinifolia Salisb., Galanthus nivalis L., Gladiolus imbricatus L. are found on the eastern border of their distribution. The nature conservation structure includes 4 species from the Bern Convention on the Conservation of European Wildlife and Natural Habitats (Dracocephalum ruyschiana L., Pulsatilla patens (L.) Mill s.l., Salvinia natans L., Ostericum palustre (Bess) Bess); 3 species from the supplement to the CITES Convention (Adonis vernalis L., Cypripedium calceolus L., Orchis militaris L.), 27 species from the Red Book of Ukraine (Lilium martagon L., Allium ursinum L., Neottia nidus-avis (L.) Rich, Stipa pennata L.), 49 species from Sumy region rare species list (Clematis recta L., Pulsatilla patens (L.) Mill., Eremogone saxatilis (L.) Ikonn., Drosera rotundifolia L., Pedicularis kaufmannii Pinzg., Carex limosa L., C. umbrosa Host.). In addition, we suggest including into this list Sanquisorba officinalis L., Briza media L., Beckmania eruciformis (L.) Host., Melica nutans L., Coronilla varia L., Salvia nutans L., Scilla siberica Haw., Corydalis solida (L.) Clairv., Valeriana officinalis L., Vincetoxicum hirundinaria Medic., Menyanthes trifoliata L., Hesperis matronalis L., Naumburgia thyrsiflora (L.) Rchb., Thalictrum aquilegifolium L., T. minus L., Verbascum nigrum L., Polygonatum multiflorum (L.) All. It was found that among the rare species of the region mesophytes predominate and they are confined to meadow and forest habitats. To a lesser extent, xeromesophytes and xerophytes of meadow-steppe, as well as hygrophytes and hydrophytes of shoreline and water habitats are represented. The nature reserve fund of the region was analyzed according to the methodology of assessing the nature reserves by botanical value priority criteria. To optimize the region's nature reserve fund, a rationale for creating a landscape reserve of local significance “Zvenyhorods'ky” with a total area of 2,000 hectares was compiled, giving it the status of a regional biodiversity centre.
Vegetation of the ‘Mierzwice’ nature reserve and its protection
