Biosystems Diversity

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Introduction
The study and conservation of plant diversity is one of the most relevant topics in currect botany. The Shenzhen Declaration adopted at the XIX International Botanical Congress (23-29 July 2017, Shenzhen, China) endorses seven major priorities for strategic actions in the plant sciences. Two of them are to accelerate the inventory of life on Earth for the wise use of nature and the benefit of humankind and to value, document and protect indigenous, traditional and local knowledge about plants and nature (Crane et al., 2017). So detailed floristic research on natural plant communities for their preservation is nowadays very important.
The main aim of floristic research is to provide botanical inventory of separate local or regional flora associated with some territory. This is the one of the simplest forms of botanical study and is rather popular since it needs no special equipment. The final result of this study may be publicshed mostly in three forms: as a checklist (a short vascular plant species list without any comments), a conspectus (a checklist with comments on plant species distribution, ecology, conservation status, etc.) and a flora (a fundamental monographic paper with identification keys, morphological descriptions, detail data about plants species area of distibution, etc.).
Advances in molecular biology and plant taxonomy in the past 30 years require a new approach to regional floristics. The new revolutionary system of angiosperm plant classification elaborated by the Angiosperm Phylogeny Group was published between 1998 (APG, 1998) and 2016 (APG IV, 2016). The nomenclatural data based on results of the Linnean Plant Name Typifications Project (Jarvis, 1992(Jarvis, , 2007 and similar studies on the plant name typification (Moberg & Nilsson, 1991; Al-Shehbaz & Barriera, 2019; Peruzzi et al., 2019) have great significance for plant taxonomists. Many current authors have emphasized that both mole-cular phylogenetic and nomenclatural data are to be summarized in current floristic checklists, conspectuses and floras (Heywood, 2000;Li, 2008). The one of recent fundamental working projects based on these principles is "Flora of Uzbekistan" (Sennikov et al., 2016) but similar studies have been previously organized and realized for Iran with adjacent areas (Akhani, 2006) and Turkey with the East Aegean Islands (Davis et al., 1998). During the last 10 years several resumptive plant checklists and conspectuses for separate Europaean countries were also publishedfor the Czech Republic Steppe communities are among the zonal vegetation types of Ukraine but they need conservation since a large number of sites with this vegetation are currently destroyed. Previously steppe areas were quite widespread in the Forest-Steppe zone of Ukraine but now in Poltava region they occupy small areas on ravine and river valley slopes. The flora and vegetation of steppe territories distributed near Poltava town have not been studied completely. Some information existing in literature sources (Illichevskyi, 1927(Illichevskyi, , 1928Andrienko et al., 1996;Bayrak-Smolyar & Korotchenko, 1996;Bayrak, 1997;Bayrak & Stetsiuk, 2005Shaparenko, 2012) is fragmentary, partly outdated and mostly associated with separate threatened vascular plant species. During the last 15 years (2005-2019) we studied steppe vegetation in Poltava district and found several valuable steppe plots not mentioned in botanical literature sources. The only wellknown territory presented in this paper is "Rozhayivskyi" local botanical reserve; detailed information about its flora was generalized in our previous paper (Davydov & Gomlya, 2016).

Materials and methods
This research is based on the data of the field work by the authors in 2005-2019 on the steppe territories distributed near Poltava town and in Poltavskyi administrative district of Poltava region (Oblast) in general. For studying the flora of steppes of this region we chose five the most valuable key locations which hold numerous rare species. The first location (AR -Abazivka-Rozhayivka) is situated on slopes of the left bank of the Poluzirya River between Abazivka and Rozhayivka villages. It consists of the territory of "Rozhayivskyi" local botanical reserve and adjacent steppe plots. A list of vascular plants species found by us in this location was published in 2016 (Davydov & Gomlya, 2016). However one of us (D.A. Davydov) on his field expedition in 2017 and 2018 found here several new species not mentioned in our previous paper so they have been added and indicated in the text as "!" for AR. The second location (K -Kostochky) includes steppe communities on the slopes of the right bank of the Poluzirya River near Kostochky village. The third steppe complex (B -Buhayivka) is located on ravine slopes near Buhayivka village. The fourth territory (M -Machukhy) has a cluster structure including several ravine complexes distributed to the south of Poltava town near Machukhy village. The fifth territory (IZ -Ivonchentsi-Zhuky) neighbouring upon the borders of Poltava town (Ivonchentsi) is situated on slopes near Zhuky village ( Fig. 1). In this checklist the frequency of distribution is presented by the following scale: c (common) -this species is common on all (or almost all) plots of the studied steppe locations and forms numerous populations; nc (not common) -the species is found on many (but not all) plots of the studied steppe locations and it is not very common and characteristic; r (rare) -the species is found on several plots of studied steppe location, it is locally distributed; vr (very rare) -the species is very rare on this territory, it was found only several times in different years; "-" -the species has not been found on this territory. Sozological status for the vascular plants found has been indicated before the plant species names according to current nature conservation documents: "**" -the third edition of the Red Data Book of Ukraine (Chervona, 2009); "*" -the list of locally rare plants within Poltava region adopted by Annex 2 to the Decision of the 18th session of the fourth convocation of the Poltava Regional Council in February 2004 (Bayrak & Stetsiuk, 2005). The second step of our research was critical analysis of taxonomy and nomenclature of vascular plant species found on the studied steppe territories. It has beed made by D. A. Davydov, who analyzed more than 500 publications with original descriptions (protologues) of steppe plant taxa and taxonomic papers about their current systematic positions based on results of both traditional morphological and molecular phylogeny research by different authors. So the main synonym names are indicated in our list with very brief comments (if needed) and citations of major systematic revisions for separate problematic taxa.
Herbarium specimens of steppe plant species from studied locations (about 1 000 sheets) are preserved in herbaria of V. G. Korolenko Poltava National Pedagogical University (PWU) and M. G. Kholodny Institute of Botany of NAS of Ukraine (KW).

Results
The species composition of the analyzed steppe flora includes 401 species from 237 genera and 52 families: The full species list of vascular plant species published here has great significance for regional floristic studies. It includes 13 species not mentioned in a recent publication for Poltava administrative region (Bayrak & Stetsiuk, 2008). Nine of them (Malus domestica, Prunus armeniaca, P. cerasus, Rosa mediata, Linum hirsutum, Cuscuta planiflora, Crepis foetida, Hieracium robustum and Pilosella brachiata), however, have been earlier reported by us from Abazivka-Rozhayivka location (Davydov & Gomlya, 2016); one (Rosa antonovii) -indicated by us for Poltava district (Gomlya & Davydov, 2008), one (Helianthus annuus as a casual alien)cited by Dvirna (2012), one (Rosa borysthenica) -cited by Dubovik (1989) and only the one species (Hemerocallis fulva) has never been mentioned for Poltava region previously.
Hemerocallis The Abazivka-Rozhayivka steppe location comprises all seven nationally and 17 regionally rare species. Kostochky -five nationally and 14 regionally rare species, Buhayivka -three nationally and 12 regionally rare species, Machukhy -three nationally and nine regionally rare species, Ivonchentsi-Zhuky -two nationally and four regionally rare species. The most widely distributed rare species are Crocus reticulatus, Stipa capillata (Red Data Book of Ukraine), Muscari neglectum and Cota tinctoria (regionally rare) found on all studied territories. Otherwise, 12 rare species (Gladiolus imbricatus, Stipa pulcherrima, Iris pumila, Bellevalia ciliata, Aegilops cylindrica, Oxytropis pilosa, Rosa chrshanovskii, Dianthus eugeniae, Vinca herbacea and Jurinea multiflora, including two not confirmed by our data Linum perenne and Trinia kitaibelii) were found only the on one steppe territory and belong to the very locally distributed category. Monitoring of their state through further investigations is necessary.
The studied key steppe territories near Poltava town are highly representative, they cover populations of 32 rare steppe species from 33 found in Poltava district (except Pedicularis kaufmannii Pinzger occuring on slopes between Vytivka and Abazivka villages) and from 68 (47.1%) found in steppes of Poltava region (Davydov & Gomlya, unpublished data). So the preservation of these locations as objects of the Ukrainian nature reserve fund is a priority objective.

Conclusion
Our study of the vascular plants on key steppe territories near Poltava emphasized their important scientific value as plots with high plant diversity for the steppe sites within the Forest-Steppe zone of Ukraine. The primary task for further research is to organize the protection of these most important steppe areas and the monitoring for their condition in the future. In our opinion, regional floristic studies are very promising and relevant today. However, in the light of the current development of botany they need be coordinated and connected with new data about taxonomy and nomenclature of separate taxa (species typification, critical revision of their circumscription based on new molecular phylogenetic data, discussion on the phylogeny and evolution of high rank taxa, etc.). With the supporting of such conditions the obtained results will have not only local but global scientific significance. Sometimes the study of new papers in the field of taxonomy or nomenclature with the new names presented there instead of the widely accepted ones causes their categorical rejection. However, it is unacceptable to willfully ignore these publications.