Drosera in Ukraine : Ecological , сhorological specifics and phytosozonomical characteristics

The paper presents a chorologically systematized description of all taxa of the Drosera L. genus in Ukraine. We performed an analysis of environmental conditions, phytocoenotic characteristics and found new locations of sundew. We generalized the morphometric parameters and proposed a concept – “leaf roundness index”; and recommended including Drosera rotundifolia, Drosera x obovata in the next edition of the Red Data Book of Ukraine due to the contraction of their habitat and their high degree of vulnerability to unfavourable environmental factors and anthropogenic impact; we reccommend growing Drosera ex-situ on the example of Kremenets Botanical Garden with further repatriation in-situ; proved the efficiency of the proposed methods of farming cultivation. The paper substantiates the complex of phytosozological criteria, measures for protection and reproduction of the endangered species of Drosera genus. We suggested a hypothesis about the independence of the taxon of Drosera x obovata. Despite the fact that Drosera longifolia x D. rotundifolia is generally considered to be sterile hybrid, individuals breed vegetatively, are fertile and retain germinability after germination, and have a clearly specific ecotype, sometimes loci are isolated from parent species. To isolate the Drosera x obovata as a single taxon, additional phylogenetic studies are needed, but as a rare, disappearing taxon it needs protection and background monitoring of populations. The area of greatest phytosozological value for sundews in Ukraine is Western Polissia (Volyn, Rivne regions) (D. longifolia – 31, 20 sites, D. intermedia – 31 and 30 respectively). Drosera longifolia is on average distributed slightly further south in Ukraine than D. intermedia, although both taxa are confined to the humid, boreal zone. D. rotundifolia is most widespread in the humid zone (Polissia, the Carpathians). Despite the presence of Drosera x obovata in the Cheremskyi, Rivnenskyi Nature Reserve, Shatskyi National Nature Park, and several landscape reserves, the taxon is continuing to disappear due to succession, afforestation, water regime change etc.


Introduction
In the conditions of global changes of the environment, the priority task is theoretical and conceptual substantiation, methodological recommendations and practical measures for the protection of phytodiversity as a medium-critical basis of balanced development of the biosphere. In the conditions of intensified anthropogenic impact, transformation of biotopes, it is necessary to determine ecological-chorological peculiarities of rare, endangered species of plants and to recommend sozological criteria for their survival and reproduction. The abovementioned problems are very important for heterotrophic helophytes, which are among the most vulnerable to the effects of dessication of wetlands and peatlands, and in particular for species of the Drosera L. genus (the family -Droseraceae).
As is known, almost 50% of peatlands are degraded in Ukraine, the area of wetlands is 4.5 million hectares (1.6% of the state territory), drained lands -3.3 million hectares . That means that half of the potential ecotopes of helophytes are lost. In addition, even in the objects of the nature reserve fund, the condition of the populations of rare marsh plants, in particular sundews is deteriorating. This is due to the natural processes of succession, sylvatization, the mineralization of the substrate, change in the hydrological regime, the transformation of ecotopes, etc. Consequently, the problem of ecological assessment of the low frequency, disappearing helophytes on the example of sundews is highly topical and requires a priority solution in order to optimize the conservation of phytodiversity of rare species. The aim of the work is to optimize ecosozonomical conceptual approaches and practical monitoring measures for preservation of taxa of Drosera L. in Ukraine based on scientific substantiation. To achieve the goal of the work the following tasks were to be performed: 1) to unify and systematize bibliographic information, data of the herbarium funds; 2) to conduct field expeditions with geobotanical descriptions, selection of herbarium and samples of substrate (peat), water; 3) to study the ecological conditions, chorology of habitat, to describe the composition of phytocoenoses, to determine the type of substrate; 4) to determine the morphometric parameters and carry out correlation analysis; 5) to prove experimentally the possibility of growing ex-situ and repatriation in-situ; 6) to develop criteria for protection of sundews and offer effective measures for the conservation and reproduction of populations.
The practical significance and prospects of the research -the obtained results can be used in preparing the next edition of the Red Data Book of Ukraine, in the implementation of the programme "Chronicle of Nature" by national natural parks, biosphere reserves, nature reserves, in the work of the relevant departments of the Ministry of Ecology and Natural Resources of Ukraine and regional state administrations, forestry and water management. It is advisable to create an electronic database of ecotopes with geographical coordinates for GPS. According to the developed methodological recommendations, it is worthwhile to start the programme for the restoration of weakened, and if possible disappeared, sundew populations.

Materials and methods
We analyzed bibliographic (Montrezor, 1886(Montrezor, -1891Pachoskyi, 1897Pachoskyi, , 1913Kholodnyi, 1938;Flora URSR, 1953;Andrienko, 1977Andrienko, , 2010Denisova, 1981), actual data and herbarium collections of all known habitats of Drosera L. of the Ukrainian natural flora. We ana-lyzed certain foreign publications (Cheek, 1998(Cheek, , 2001Podbielkowski & Sudnik-Wojcikowska, 2003) which confirmed the similarity of conditions of habitats in Europe. Our work was also based on the materials of our own expeditionary field research conducted during 2012-2017. The performance of the work is associated with basic research "Methodological fundamentals of sustainable development of wetland landscapes and peat ecosystems" (2011-2015) degree thesis, No 0111U003228, "Implementation of an integrated Pan-European system of ecological management of agricultural landscapes and biodiversity conservation in Ukraine" (2016-2020) degree thesis No 0116U004064 (Project manager -V. V. Konishchuk) and the preparation of the dissertation "Ecological preconditions for reservation of heterotrophic helophytes of genus Drosera L., Pinguicula L. in Ukraine ex-situ" (O. I. Skakalska). The research was carried out by the route method with reconnaissance. Geobotanical descriptions were carried out according to generally accepted techniques (Hryhora & Yakubenko, 2005). In addition to the original research, for the chorological analysis of rare plant species we analysed the literary data and materials from the herbarium resources of the M. H. Kholodnyi Botanical Institute of NAS of Ukraine, Rivne Regional Museum, Volyn Regional Museum, Institute of Agroecology and Environmental Management of NAAS. The list of the habitats in accordance to the administrative principle includes the settlement, tract, the object of natural reserve fund, authors (Flora URSR, 1953;Andrienko, 1977Andrienko, , 2010, and the information about the herbarium. The water analysis was determined by a portable certified device: pH-OVP meter / conductivity meter / solimmer / thermometer Ezodo 7200. Peat ash content was determined using the standard method of burning in a muffle furnace Veb Elektro Bad Frankenhausen MLW Elektro LM 312.11 Typ L1, with weighing on analytical scales Nagema VEB Groβwaagen Berlin IV S/3-3. For laboratory analysis of peat, a light monocular microscope Konus Research (max 1600 x ) with digital camera Ucmos 14 MPix was used.
Digital images were made by the Nikon D3200. Selected samples of plants in agreement with the objects of the natural reserve fund were transferred to the Herbarium of the M. H. Kholodnyi Institute of Botany of NAS of Ukraine (KW), Institute of Agroecology and Environmental Management of NAAS of Ukraine. Taxonomy is given according to generally accepted conventions (Mosiakin & Fedoronchuk, 1999) for the International Plant Names Index (IPNI). Latin transliteration for geographical names and surnames is provided in accordance with the requirements (Postanova KMU, 23.12.2015). Bioethical norms were not violated.

Results
Three species and one hybrid of sundew grow in-situ in Ukraine -Drosera longifolia L. (syn. D. anglica Huds.) (great or English sundew), D. intermedia Hayne (oblong-leaved or spoonleaf sundew), D. rotundifolia L. (common or round-leaved sundew), D. x obovata Mert. et W. D. J. Koch. The first two species are included in the Red Data Book of Ukraine (2009) with protected status as vulnerable, and were included in the two previous editions of the Red Book. D. rotundifolia has a regional conservation status in the vast majority of its natural range, in particular in Vinnytsia, Volyn, Dnipropetrovsk, Donetsk, Zakarpattia, Ivano-Frankivsk, Kyiv, Luhansk, Lviv, Poltava, Rivne, Sumy, Ternopil, Kharkiv, Khmelnytskyi, Cherkasy, Chernivtsi regions (Ofitsiyni pereliky..., 2012), except in Zhytomyr and Chernihiv regions. In Ukraine, there is no protection status for D. x obovata. Below there is a summary of the biological, ecological, and chorological characteristics of all taxa of Drosera in Ukraine in terms of bibliographic, herbarium and copyright data. In the legend, the drawings fix all known places of location of record according to the literary and herbarium information, some are considered lost or not confirmed. Drosera longifolia L. Heterotrophic, circumpolar plant on the southern boundary of its range. D. longifolia L. is a glacial relic (Andrienko, 2010). The species is common in northwestern parts of Eurasia (Northern Europe, Scandinavia and the taiga, Mongolia) and the mid-northern latitudes of North America, on the Kurile Islands, Hawaii, Kamchatka, Primorye and Sakhalin. In Ukraine, it occurs in Polissia, in Roztochia, Forest-Steppe, mainly Left-Bank. The populations are small, sometimes forming quite thick curtains. Many populations, primarily in the Dnipro regions and Forest-Steppe, represented in the herbarium collections, are now lost. The main reasons for the change in abundance are drainage and development of swamps, peat extraction, extraction of amber, carbonate rocks, afforestation and formation of meadows in mires, and the narrow ecological amplitude of the species. Ecotope conditions: flooded, mesoeutrophic, flow, carbonate, glacial-karst marshes with pH 6.0-7.5 (less often 4-6), small-grained gypsum, sedge-sphagnum peat with a decomposition degree of 10-20% (less than 30%). The species is an assectator in the groups. It grows in groups of class Scheichzerio-Caricetea fuscae Tüxen 1937, associations: Caricetum lasiocarpae Koch 1926, Caricetum limosae Braun-Blanquet 1921, Rhynchosporetum albae Osvald 1923, Sphagno-Caricetum rostratae Steffen 1931 etc. Lightloving hygrophyte. General biomorphological characteristics: hemicryptophyte; perennial plant with linear-or oblong and wedge-shaped laminae, the height of flowering stems of 10-25 (sometimes 35) cm; stalk upright; leaves in basal rosette directed obliquely upward, linear wedge-shaped, 15-40 mm long, 3-5 mm wide with membranous brown stipules, highly rooted to the petiole, split at the top on setaceous parts, the top covered with glandular hairs; flowers are white, collected in a raceme; fruit is an ovoid single-pore capsule; sepals at the base are increased, oblong, finely granular and serrate, 5-6 mm long, about 2 mm wide; lobes are spadeshaped, white, 5-7 mm long, +(-) 3 mm wide; ovary is obovate-ellipsoidal; 3 columns, from the base with 2 separate arising parts, clavate on top; the capsule is egg-shaped, longer than the calyx (Fig. 1). The seed is spindle-shaped, with a loose adjacent skin. Blossoms in July-August. Gives fruits in August-September. It is propagated by windborne seeds. It is perennial. The number of chromosomes 2n = 40, hybridizes with D. rotundifolia, some cultivated hybrids are also known.
The species is included in the Red Book of Ukraine, the Czech Republic, Slovakia, Hungary, Romania, Briansk, Vologda, Kaluga Oblasts of the Russian Federation, the Red List of Plants and Mushrooms of Poland. According to official materials (Red Data Book of Ukraine, 2009), 25 sites are indicated according to herbarium collections and 22 according to the literary data. According to the literature, herbarium data, which we analyzed, and our own data, the chorological characteristic of D. longifolia L. is as follows (Fig. 2).
Locations  Orlov, 1989Orlov, , 1990Orlov, , 2005  Drosera intermedia Hayne. This is a heterotrophic and holarctic plant on the southeastern border of an isolated European part of its range. In Ukraine, it is a disjunctive range species. The easternmost boundary of the location is the basin of the Desna River; the southern is in the intersection of the rivers Udych and Southern Bug. The range of the genus covers the Atlantic, the Central and Eastern Europe, North America (USA, East Canada), Cuba, South America (Venezuela, Brazil), less often the Caucasus, Turkey. In Ukraine, it occurs mostly in Right-Bank Polissia, or less often -in the Forest-Steppe. The populations are small, in places the density is high, it has decreased in abundance, especially in Prydniprovya. In the coenoses, it is an assectator, highly competitive, explerent (plants of low cenotic capacity, but which can quickly cover new areas -Editor's note), stress-tolerant plant, in the pioneer phytogroups it is the dominant, the co-dominant. This perennial plant is 5-12 cm tall (Fig. 3). The stem at the base is arising, ankle-like. The leaves are positioned in pre-root rosette, orientated upward, with with ellipsoidal, wedge-shaped lamina with a petiole which is longer than it; the bases of the stipules grow into the petiole and are split almost to the basis into or lanceolate-bristle of spike parts.
The leaves on the top and on the edges are covered with glandular hairs. Flowers are pale white. Flower stalks are single or by 2-3, kneelike ascending on the lying base, 3-12 (15) cm tall, slightly exceeding the leaves. Inflorescences have 4-10 flowers. Sepals are oblong, 3-4 mm in length, 3 mm in width; The ovary is obovate, 3 columns, to the base with 2-split, integral, ascending, apex-enlarged and, sometimes, sinuatecut parts. The plant blossoms in June -July. It fruits in August. Fruits are pear-shaped, single-pore, capsule with longitudal furrows. The seed is obovate, reddish-brown, densely humped. The plant propagates by seeds. It is perennial.
Conditions of growth locations are mesorophic, flooded mesoeutrophic marshes (often of carbonate type) with pH 6.0-7.5 (less often 4-5), sedge-sphagnum peat, peat composed of different herbs with low ash content and a degree of decomposition of 10-20% (less often 30-40%) mostly with running mode. In addition to marsh ecotopes, it grows on quaking bogs of karst and proglacial aquaceous-glacier types of lakes, on trodden marsh paths, on a sandy substrate with gley of periodically flooded ephemeral water bodies, channels and gaps in open lighted areas. Hygromenosophyte. This species is included in the Red Data Book of Ukraine, Belarus, Lithuania and the Red List of Plants and Mushrooms of Poland. According to the materials of the Red Book of Ukraine (2009), 36 places of records are indicated according to the herbarium collection and 13 according to the literary data. According to the literature and herbaric data we analyzed and data of our own, the chorological characteristic of D. intermedia is as follows (Fig. 4).
A stellar perennial plant, propagates vegetatively. The stalk is straight, two times longer than the rosette of the pre-root leaves. The laminae are obovate, in length 1.5-2.0 times greater than the width (Fig. 5). The surface is pubescent, glandular. Inflorescence is a tassel. Perianth is actinomorphic. Sterile hybrid, vegetative reproduction is more intense than among related species. Sometimes can be isolated from the mother species, gives fruits, but the capsules are likely to be underdeveloped. Flowers are white. Blossoms in July-August. It is perennial, hygrophyte, and mesotroph.
The taxon is included in the Red Book of Kaluga Oblast of Russia as a very rare species on the verge of extinction. Has no nature-protection status in Ukraine. We suggest including this disappearing hybrid into the Red Book of Ukraine similarly to some unique taxa of algae (Osnovy algosozologii, 2008 5-7.5 (rarer 4-5), flooded sedgesphagnum, hypnum peat and peat composed of different herbs and with low ash content and a decomposition degree of 10-20% (less than 30%). According to the literature, herbarium data and data of our own, the chorological characteristic of Drosera x obovata Mert. et W. D. J. Koch is as follows (Fig. 6).
Kyiv  Drosera rotundifolia L. This is a boreal, circumpolar species; distributed in Europe, the northern part of Asia, Siberia, Arctic and Temperate part of North America. In Ukraine, it grows in Polissia, Northern Forest-Steppe, in the Carpathians to the subalpine belt (Andrienko, 2010), in Zakarpattia Oblast, there are no places of record in the Crimea. Occasionally, small loci were found in the south of the Forest-Steppe and even in the Steppe .
Leaves in the pre-root rosette are stretched, with long petioles and with a round or transversal oval laminae; the stipules connate to the petiole, before the middle or higher are split into almost bristly parts. Flower stems are single or more often in pairs thin, reddish, straight, sometimes winding, 10-25 (30) cm tall, several times longer than the leaves (Fig. 7).
Inflorescences are mostly multiflorous; sepals at the base are grown, oblong, small glandular-serrate, 5 mm long, approximately 1.5 mm in width; lobes are white, spade-shaped, 5-6 mm in length, approximately 3 mm in width; the ovary is ellipsoidal, has 3 columns, from the base of 2-split, with ascending, clavate at the top, integral, rarer sinuate-cut parts. The capsule is egg-shaped, and longer than the calyx. Seeds are small, narrow spindle-shaped with brown, loosely adjoining skin. Blossoms are in June -August. The plant is medical.
Conditions of growing locations are humid, wet pine forests and boreal forests, sandy substrates with gley of periodically flooded ephemeral water bodies, channels and gaps in open, non-darkened areas, oligotrophic, mesotrophic, flooded meso-eutrophic marshes, mainly sedgesphagnous quaking bogs of karst and proglacial types of lakes, belon- D. rotundifolia, the round-leaved sundew, usually grows in groups with other species of the Drosera L. genus, but is more commonly distributed in wide amplitudes of ecological valency. Water pH 3-5 (6-8), peat of different ash content with decomposition degree from 10-20% to 30-50%, possibly substrate from shrub remains, sod-podzolic soils, loam, rocky surfaces with lichen-moss coverage or gley-slit sediment. Can be dominant in sub-associations. The plant is perennial, light-loving oligotroph. The round-leaved sundew is included in the Red List of Mushrooms and Plants of Poland as a species on the verge of extinction, Red Book of Briansk, Kaluga, Orlov Oblasts of RF as a rare species with falling abundance. It has the status of a regional rare species in most regions of Polissia. It is recommended to include the species into the next edition of the Red Book of Ukraine. According to the literature and herbarium data we analyzed, and our own data of the chorological characteristic of D. rotundifolia L. is given (Fig. 8).
For all taxa of Droserae, the degree of natural renewal is unsatisfactory. We first recommended the provision of state protection for all species of Drosera (V. V. Konishchuk, Zapovidna sprava v Ukraini, 2004). Mostly, sundews are protected in the objects of the nature reserve fund, they grow in groups in marshes and are protected by the Green Book of Ukraine (2009). Among the types of natural habitats of Ukraine where sundews grow and are protected by the jurisdiction of the Convention for the Protection of Wild Flora and Fauna and Natural Habitats in Europe (September 19, 1979, Bern, Switzerland) the dominant are: 3140. Hard oligo-mesotrophic waters with benthic vegetation of Chara spp., 3150. Natural eutrophic lakes with Magnopotamion or Hydrocharition -type vegetation, 6410. Molinia meadows on calcareous, peaty or clayey-silt-laden soils (Molinia caerulea), 7110. Active raised bogs, 7120. Degraded raised (oligotrophic) bogs still capable of natural regeneration, 7140. Transition mires and quaking bogs, 7150. Depressions on peat substrates of the Rhynchosporion, 7210. Calcareous fens with Cladium mariscus and species of the Caricion davallianae.
The dynamics of peat accumulation, the degree of mineralization, phytoadaptation to climate changes and the orientation of the successions, may correlate with the ecological condition of phytocoenoses with sundews. The priority phytosozological task remains the issue of repatriation and monitoring of Drosera L. taxa.

Conclusions
Hydrohelophytes of the Drosera L. genus, despite being protected in a large part of the territory of the Nature Reserve Fund of Ukraine (nature reserves, national parks, Ramsar wetlands, reserves etc.) are very sensitive to the slightest negative changes in the environment (including changes in water regime) and may be an indicator of the ecological condition of the environment. As a result of succession, sylvatization of open sedge-sphagnum, hypnum marshes, reduction of trampling and cutting down of marsh plants (upper layer -phytocoenoses of Carex rostrata Huds., C. lasiocarpa Ehrh.), the sundews are displaced by other species of flora. In addition to feeding on insects -mosquitoes (Culicidae), black flies (Simuliidae), syrphid flies (Syrphidae), sundews use other sources (moving forms of macroelements, microelements and chemical compounds of the substrate of the pedosphere, water, photosynthesis energy, etc.), thus this specific group of plants would be more correctly termed heterotrophic rather than insectivorous species.
We have proved the possibility of growing all Drosera L. taxa of the natural flora of Ukraine ex-situ with subsequent repatriation subject to the appropriate scientific substantiation and the availability of legal support. Phytososonomic criteria for Drosera L. species are as follows: chorological, population, ecological-coenotic, florogenic, ontogenetic, pragmatic and aesthetic.
In Ukraine, the area with the most important phytosozological value for sundews in Ukraine is Western Polissia (Volyn, Rivne region) (D. longifolia -31, 20, D. intermedia -31and 30 growing locations respectively). Round-leaved sundew is most widespread in the humid zone (Polissia, Carpathians). The vanishing taxon -D. obovata, despite its presence in Cheremskyi, Rivnenskyi Nature Reserves, Shatskyi National Nature Park, several reserves, is disappearing due to succession, afforestation, water regime change etc. Of 17 known locations 2 are lost. In Polissia we have reliably confirmed almost all growing locations of sundrews, some have preserved autochthonous distribution for over 100 years since the onset of destructive anthropogenic impact (Western drainage-meliorative expedition, Y. I. Zhylinskyi, 1873, etc.), others need clarification, conducting additional recording and monitoring, four new populations have been discovered. Some populations periodically renew, particularly D. intermedia. In some cases repatriation is needed, therefore we provide all known places of record according to the literature, herbarium data and data of field surveys. The most vulnerable ecotopes are in the Forest-Steppe and drained mires. Growing locations of D. rotundifolia were previously sited on above floodplain pine terraces of the Dnipro, Siverskyi Donets, South Bug, in the outskirts of Kharkiv, most of them are lost (Andrienko, 2010). Y. K. Pachoskyi demonstrated the data on sundews in the territory of the current Kaniv reservoir, valley of Trubizh, Dnipro, which have disappeared. As a result of climate change, reduction of functions of self-regulatory ecological condition of hydrohelolandscapes, complete cutting down of the trees in the areas, extraction of amber, quarry development of carbonate rocks and draining of peat swamps, the ecological condition of typical biogeocenoses of hydrohelophytes continues to deteriorate. Therefore, we suggest the inclusion of all taxa of Drosera L. in the next edition of the Red Data Book of Ukraine.