ACTA BIOLOGICA SLOVENICA LJUBLJANA 2018 Vol. 61, Št. 2: 47-70 ABS The vascular flora of Kopački rit Nature Park (Croatia) Vaskulame rastline Naravnega parka Kopački rit (Hrvaška) Vlatko Rožaca, Dragan Prlicb, Siniša Ozimecc* a Public Institution Kopački rit Nature Park, Mali Sakadaš 1, Kopačevo, HR-31327 Bilje, Croatia b Josip Juraj Strossmayer University of Osijek, Department of Biology, Cara Hadrijana 8/A, HR-31000 Osijek, Croatia c Josip Juraj Strossmayer University of Osijek, Faculty of Agrobiotechnical Sciences Osijek, Vladimira Preloga 1, HR-31000 Osijek, Croatia ^correspondence: sozimec@pfos.hr Abstract: Kopacki rit Nature Park is a large fluvial-marshy floodplain, situated in the northeastern Croatia, between courses of the Danube and the Drava Rivers. Due to exceptional biological and ecological values of this floodplain area in the middle course of the Danube River, it had been protected since 1967; proclaimed as Nature Park in 1999 and from 2012 is a part of the UNESCO Transboundary Biosphere Reserve Mura-Drava-Danube. This paper lists a total of 522 vascular plant taxa, classified in 295 genera and 96 families, recorded for Kopacki rit Nature Park. The list is completed according to checked literature records and data for 114 new taxa, found during the floristic investigation carried out from 2010 to 2018. Taxonomic, ecological and phytogeographical analyses are presented. Hemicryptophytes dominate (39.3%) in the biological spectrum, followed by therophytes (23.8%), geophytes (12.6%) and hydrophytes (12.5%). In the chorological spectrum, the most numerous are plants of Eurasian floral elenent (32.8%), followed by Cosmopolites (27.4%), and European floral element (10.7%). Out of 53 recorded allochthonous plants, 26 are invasive alien plant species. According to protection and conservation status at the national level, 55 taxa are listed in the Red Book of Vascular Plants of Croatia and 53 taxa are strictly protected. One species, Marsilea quadrifolia, is listed in Annex II of the Habitat Directive. Key words: Kopacki rit, Danube, flora, biodiversity Povzetek: Naravni park Kopački rit je obsežna poplavna ravnica, ki se nahaja na severovzhodu Hrvaške, med rekama Donavo in Dravo. Zaradi izjemne biološke in ekološke vrednosti tega poplavnega območja v srednjem toku reke Donave je območje od leta 1967 zaščiteno. Naravni park je bil razglašen leta 1999 in od leta 2012 je območje del prekomejnega biosfernega rezervata UNESCO Mura-Drava-Donava. V Naravnem parku Kopački rit je bilo zabeleženih 522 vaskularnih rastlinskih taksonov, ki sodijo v 295 rodov in 96 družin. Seznam temelji na podatkih v literaturi, katerim smo dodali 114 novih taksonov, ki so bili popisani med florističnimi raziskavami, opravljenimi od leta 2010 do leta 2018. V prispevku so predstavljene taksonomske, ekološke in fitogeografske analize. Med taksoni prevladujejo hemikritopiti (39,3 %), 48 Acta Biologica Slovenica, 61 (2), 2018 sledijo jim terofiti (23,8 %), geofiti (12,6 %) in hidrofiti (12,5 %). Najštevilčnejši so evrazijski florni elementi (32,8 %), sledijo kozmopolitske vrste (27,4 %) in evropski florni elementi (10,7 %). Od 53 zabeleženih alohtonih rastlin je 26 invazivnih tujerodnih rastlinskih vrst. Ključne besede: Kopački rit, Donava, flora, biotska raznolikost Introduction Floristic studies in the area of Kopacki rit Nature Park were only occasional in the past. Numerous records, sometimes with a description of geographically uncertain localities, are included in publications related to the wider area of the Slavonia and Baranja regions. The earliest report about plants in the present-day Kopacki rit area dates back to the 18th century. Count Luigi Ferdinando Marsigli collected information on the indigenous plants of the Danube region and presented it in the sixth volume of the monograph: Danubius Pannonico-Mysicus (Marsigli 1726). Among the listed plants and localities along the Danube course, the mouth of the Drava River ("circa influxum Fluvii Dravii") was recognised as the collection hot spot of several plants. Paul Kitaibel made field excursions in Baranja region in the period 1799 - 1808 (Purger and Csiky 2008), and some of his records were published by Neilreich (1866). Adam Boros made a field visit in Kopacki rit from 24 to 27 June 1944 and reported findings of Urtica kioviensis (Boros 1944a), Veronica peregrina (Boros 1944b) and Marsilea quadrifolia (Boros 1946). Floristic studies have been renewed and intensified in the period from the1960s up to the end of 1980s (Jovanovic 1965, Ilijanic 1968, Balatova-Tulackova and Knezevic 1975, Raus et al. 1980, 1985). Trinajstic and Pavletic (1978) investigated the aquatic vegetation and made the first record of a neophyte Azolla filiculoides in Kopacki rit. In the review of vegetation diversity in Kopacki rit Special Zoological Reserve, Topic (1989) decribed structure of 37 associations, arranged into ten classes of aquatic, marshland, ruderal, meadow and forest vegetation. During the botanical surveys in the period 1986 - 1988, Panjkovic (1990) recorded 723 taxa for the flora of the Baranja region, including several taxa found in Kopacki rit. Topic (1999) summarised all available literature data about flora and vegetation in Kopacki rit and made a list of 368 taxa for the flora of Kopacki rit. Zahirovic (2000) carried out from 1997 to 1999 an extensive field investigation of the rare and endangered plant species in northeastern Croatia, including the area of Kopacki rit. Among 467 recorded taxa, 37 had been new for the flora of the Baranja region. Distribution and ecology of two rare aquatic plants in Kopacki rit, Azolla filiculoides and Wolffia arrhiza, was described in details. Topic and Ozimec (2001) reported the first finding of Typha laxmannii as a new to the Croatian flora. Latest discoveries treated two new taxa to the flora. An invasive aquatic species Elodea nuttallii was found in 2006 in the drainage channels in Kopacki rit (Kocic et al. 2014). Scirpus pendulus, a neophyte originating from North America, was discovered in July 2011 on the muddy bottom in a wet ditch in the area between Kozjak and Tikves (Ozimec and Topic 2018). Public Institution Kopacki rit Nature Park initiated and supported intensive floristic investigations in the period 2010 - 2018, combined with monitoring of rare and threatened plants and habitats. An important achievement of these activities is a complete list of the vascular flora, presented for the first time in this paper. Material and methods Study area Kopacki rit Nature Park is located in northeastern Croatia, in the angular area formed by the confluence of the Danube and the Drava River (Fig. 1). The Park covers an area of 231 km2 with an altitudinal range from 78 to 86 m a.s.l. This is a large fluvial-marshy floodplain formed during the late Quaternary (Bognar 1990). Rožac et al.: Flora of Kopački rit Nature Park 49 Figure 1: The area of Kopački rit Nature Park with position of localities where new taxa had been found. Slika 1: Območje Naravnega parka Kopački rit z lokacijami, kjer smo našli nove taksone. Data from the climatological station in Tikveš for the period 2004 - 2013 confirms that the climate is moderately warm and rainy (Cvitan 2014). Mean annual air temperature is 11.0 oC, the absolute minimum is - 25.1 oC, and the absolute maximum is 39.4 oC. The coldest month is January (0.4 oC) and warmest is July (21.9 oC). Mean annual precipitation amounts to 696 mm, the highest in June (89 mm), and lowest in January (44 mm). Mean relative humidity is 85%, highest in December and January (91% each), and lowest in July (79%). Mean annual number of days with frost is 53, and with dew is 142 days. Floodwater enters the area from both the northern and southern parts when the Danube water level exceeds the value of 81.50 m a.s.l. (at Apatin gauging station), and at water level above 83.00 m a.s.l. the entire area is filled with water. The largest water body is the Kopačko Lake with the surface of200-250 ha in the period out of flooding. The deepest one is the Sakadaš Lake with a mean depth of 7 m. The lakes are interconnected with rivers through a network of natural channels (Tadic 1999). The inflow of the Danube floodwaters towards the Kopačko Lake is distributed by the 6 km long Hulovo Channel, which is connected with the Danube course near river km 1,388. In the northern part, floodwaters are distributed by the Vemeljski Dunavac, a Danube sidearm with upper end at river km 1,407 and lower end at river km 1,392 (Ozimec and Topic 2018). Danube flooding and water stagnation are major pedogenetic factors of specific soil type characterised by fine texture and low hydraulic conductivity. The most prevalent are hydromorphic soils, particularly gleysols. Excessive wetting by floods and high subsurface water enables the evolution of hydromorphic soils (Tadic et al. 2014). Regarding the phytogeographical position, the area belongs to the Eurosiberian - North American region and the Pannonian sector of the Central European province. This is a transitory region between the vegetation of the Carpinion betuli alliance and forest-steppe zone of the Aceri tatarici - Quercion alliance (Topic and Segulja 2005). In the land use structure, freshwaters and marshland covers 40% of the total Park area, forests 30%, and the agricultural land 20% (Anonymous 2006). The area of Kopacki rit was firstly protected in 1967 under the category of Managed Natural Reserve. Its boundaries and protection categories had been changed during the fifty-year period. Existing protection status was established in 1999 by the Act of Kopacki rit Nature Park (Anonymous 1999) at total area of 231 km2 including 71 km2 of Kopacki rit Special Zoological Reserve and the Danube course between river km 1,412 and 1,382. In 1993, Kopacki rit was designated on the List of Wetlands of International Importance under the Ramsar Convention. It is included in the ecological network Natura 2000 in Croatia, with a site code HR2000394 Kopacki rit (Anonymous 2013a, 2015). The latest achievement in nature protection is the establishment of UNESCO Transboundary Biosphere Reserve Mura-Drava-Danube, proclaimed in July 2012, with Kopacki rit Nature Park as the best-preserved natural floodplain of the entire Reserve. Floristic study Field investigations were carried out in the period from 2010 to 2018, with an approval for research and collection issued by the competent state authority for the nature protection. Investigated localities (Fig. 1) where new taxa had been found are described as it follows: 50 Acta Biologica Slovenica, 61 (2), 2018 1. Wet meadows near the left bank of the Drava River (19 May 2010, 26 May 2011, 25 May 2012, 29August 2017), size about 83 ha, degraded meadow association Veronico longifoliae - Euphorbietum lucidae; 2. Fishponds "Podunavlje", basinsA, D, and E and surrounding area (2 July 2010, 1 July 2011, 11 August 2011), size about 217 ha, channels and standing water with aquatic and marshland vegetation from classes Lemnetea, Potamogetonetea and Phragmito-Magnocaricetea; 3. Fishponds "Podunavlje", basins B and C and surrounding area (15 September 2010, 2 June 2014), size about 300 ha, standing water with aquatic and marshland vegetation from classes Lemnetea, Potamoge-tonetea and Phragmito-Magnocaricetea; periodically developed amphibious alliance Nanocyperion; meadow association Arrhenatheretum elatioris along the flood protection dyke; 4. Conakut Channel and surrounding area (1 July 2011), size about 35 ha, channels and banks with vegetation from classes Lemnetea, Potamogetonetea and Phragmito-Magnocaricetea; periodically developed amphibious alliance Nanocyperion; 5. Kopacko Lake and surrounding area (12 July 2013, 24 August 2018), size about 200 ha, standing water with aquatic and marshland vegetation from classes Lemnetea, Potamogetonetea and Phragmito-Magnocaricetea; periodically developed amphibious alliance Nanocyperion; 6. Carna Channel by the road bridge (15 September 2011), size about 1 ha, ruderal vegetation developed by the road; 7. Siget forest complex (10 June 2010, 7 April 2011, 30 September 2011), size about 443 ha, forest communities of pedunculate oak and common hornbeam, association Carpino betuli-Quercetum roboris; 8. Tikves Castle complex and surrounding area (18 April 2011, 16 May 2011, 8 July 2011, 8 May 2012, 25 May 2012, 4 May 2017, 8 May 2018, 1 June 2018), size about 140 ha, forest communities of pedunculate oak and common hornbeam, association Carpino betuli-Quercetum roboris, Black walnut (Juglans nigra) plantation, meadow association Arrhenatheretum elatioris; 9. Melioration canals between settlement Kozjak and Tikves Castle complex (23 July 2010, 18 August 2010, 18 August 2011, 15 September 2011), size about 8 ha, channels and banks with vegetation from classes Lemnetea, Potamogetonetea and Phragmito-Magnocaricetea; 10. Area between settlements Tikves and Kozjak (13 July 2010, 1 July 2011, 10 August 2012, 20 August 2014), size about 40 ha, channels with vegetation from classes Lemnetea, Potamogetonetea and Phragmito-Magnocaricetea; shrubs from the class Rhamno-Prunetea at site of the former pasture; 11. Settlement Tikves and Carna Channel (10 August 2012, 23 September 2018), size about 16 ha, channels with vegetation from classes Lemnetea, Potamogetonetea and Phragmito-Magnocaricetea ruderal vegetation developed by the road. The plant taxa were determined using the standard determination keys and iconographies (Domac 2002, Javorka and Csapody 1991, Knezevic 2006, Pignatti 2002, Preston 1995, Rothmaler 2009). Agricultural and strictly ornamental plants have not been part of this research and are not presented in the results. Taxonomy and nomenclature had been adjusted according to the Flora Croatica Database (Nikolic 2018). Literature data on the presence of taxa were taken from the previously published papers and other printed sources. A complete list of the flora of Kopacki rit Nature Park contains taxa arranged in systematic order with families, genera, species and infraspe-cific taxa arranged alphabetically. Newly recorded taxa are marked with *, and invasive allien plant species with :). Rožac et al.: Flora of Kopački rit Nature Park 51 Ecological andphytogeographical analyses The plant life-forms are interpreted according to Raunkier (1937) and Pignatti (2002). The following abbreviations were used to define life forms: Ch - Chamaephyta, G - Geophyta, H - Hemic-ryptophyta, Hy - Hydrophyta, P - Phanerophyta, T - Therophyta. Chorological elements follow Horvatic (1963), Horvatic et al. (1967-1968) and Pignatti (2002). Floristic elements were described with the following abbreviations: Ce - Central European; Cir-H - Cicrcum-Holarctic; Cosm - Cosmopolites; Cul-ad - Cultivated and adventive; E - European; E-As - Eurasian; Ee-P - East European-Pontic, Med -Mediterranean; S-Eur - South European; Se-E - Southeast European. Taxa included in the Red Book of Vascular Flora of Croatia (Nikolic and Topic 2005) are indicated by an abbreviation of the IUCN risk category: CR - Critically Endangered, EN - Endangered, VU - Vulnerable, NT - Near Threatened and DD - Data Deficient. Taxa assigned as strictly protected species in Croatia under the Ordinance on Strictly Protected Species (Anonymous 2013b, 2016), are abbreviated as SP. Allochthonous flora was determined and analysed according to Mitic et al. (2008), Nikolic et al. (2014) and Flora Croatica Database (Nikolic 2018). Invasive alien plant species and their areas of origin were attributed from Borsic et al. (2008) with abbreviations: AmS - South America, AmN - North America, As - Asia, EA - Eurasia, Am - Americas, M - Mediterranean, C - in culture. Results A total of522 taxa (504 species and 18 subspecies) representing 295 genera and 96 families have been recorded for the vascular flora of Kopacki rit Nature Park (Tab. 1). As an achievement of the field investigations, carried out from 2010 to 2018, the floristic diversity increased for additional 114 newly recorded taxa. Table 1: Floristic list of Kopački rit Nature Park. Tabela 1: Seznam flore Naravnega park Kopački rit. List of taxa Investigated Floral Risk category / locality Life form element Protection statusw PTERIDOPHYTA Azollaceae Azolla filiculoides Lam. Equisetaceae Equisetum arven.se L. Equisetum x moorei Newman Equisetum palustre L. Equisetum telmateia Ehrh.* Marsileaceae Marsilea quadrifolia L. Ophioglossaceae Ophioglossum vulgatum L. Salvmiaceae Salvinia natans (L.) All. Woodsiaceae Athyrium filix-femina (L.) Roth* Hy G G G G Hy G Hy H Cul-ad Cir-H Cir-H Cir-H Cir-H Cir-H Cir-H E Cosm EN SP NT NT SP 3 8 52 Acta Biologica Slovenica, 61 (2), 2018 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw SPERMATOPHYTA MAGNOLIOPHYTINA MAGNOLIOPSIDA (DICOTYLEDONAE) Aceraceae Acer campestre L. P E Acer negundo L.:) P Cul-ad Acer tataricum L. P Se-E Amaranthaceae Amaranthus retroflexus L.' T Cosm Apiaceae Aegopodium podagraria L. G E-As Anthriscus sylvestris (L.) Hoffm. H E-As Chaerophyllum temulum L. T E-As Conium maculatum L. H Cosm Daucus carota L. H E-As Oenanthe aquatica (L.) Poir. H E-As Orlaya grandiflora (L.) Hoffm.* 8 T S-Eur Pastinaca sativa L. H Cosm Pimpinella saxifraga L. H E-As Sanícula europaea L.* 8 H Cosm Sium latifolium L. Hy Ce Torilis japonica (Houtt.) DC. T Cosm Trinia glauca (L.) Dumort. H Med Araliaceae Hedera helix L.* 7 P E Aristolochiaceae Aristolochia clematitis L. G S-Eur Asclepiadaceae Asclepias syriaca L.' G Cul-ad Asteraceae Achillea millefolium L. H Cosm Achillea pannonica Scheele H Se-E Ambrosia artemisiifolia L.' T Cul-ad Anthemis cotula L. T Cosm Arctium lappa L. H E-As Artemisia annua L. T E-As Artemisia campestris L. Ch Cir-H Artemisia vulgaris L. H Cosm Aster novi-belgii L. H Cul-ad Bellis perennis L. H Ce Bidens cernuaw L. T E-As Bidens frondosa L.*-:) 5 T Cul-ad Bidens tripartita L. T E-As Carduus acanthoides L. H S-Eur Carpesium abrotanoides L. H E-As Carpesium cernuum L. T S-Eur Centaurea jacea L. H Cosm Centaurea micranthos S. G. Gmel. H Ee-P Centaurea rhenana Boreau H E Chamomilla recutita (L.) Rauschert T Cosm Chamomilla suaveolens (Pursh) Rydb.' T Cosm Rožac et al.: Flora of Kopački rit Nature Park 53 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Cirsium arven.se (L.) Scop. G E-As Cirsium canum (L.) All. G Se-E Conyza canadensis (L.) CronquistI) T Cul-ad Erigeron annuus (L.) Pers.I) T Cul-ad Eupatorium cannabinum L. H E-As Filaginella uliginosa (L.) Opiz T E-As Galinsoga parviflora Cav.I) T Cul-ad Inula britannica L. H E-As Inula ensifolia L. H Se-E Inula salicina L. H E-As Leucanthemum vulgare Lam.* 8 H E-As Matricaria perforata Mérat* 8 T E-As Pulicaria dysenterica (L.) Bernh. H S-Eur Pulicaria vulgaris Gaertn. T E-As Senecio aquaticus Hill H E Senecio paludosus L. H Cir-H Serratula tinctoria L. H E-As Solidago gigantea AitonI) H Cul-ad Tanacetum vulgare L. H E-As Tussilago farfara L. G E-As Xanthium strumarium L. 2 T Med ssp. italicum (Moretti) D.Löve*1 Xanthium strumarium L. ssp. strumarium T Cul-ad Balsaminaceae Impatiens glandulifera Royle*-:) 8 T Cul-ad Impatiens noli-tangere L. T E-As Impatiens parviflora DC.I) T Cul-ad Betulaceae Alnus glutinosa (L.) Gaertner P E-As Alnus incana (L.) Moench. P Cul-ad Betula pendula Roth * 7 P E-As Boraginaceae Anchusa arvensis (L.) M.Bieb. T E-As Anchusa officinalis L. H E Cerinthe minor L.* 10 T S-Eur Cynoglossum officinale L. H E-As Echium vulgare L.* 10 H E Heliotropium europaeum L.* 11 T Med Lithospermum arvense L.* 10 T E-As Lithospermum officinale L.* 8 H E-As Myosotis arvensis (L.) Hill. T E-As Myosotis laxa Lehm. ssp. Caespitosa (C. F. Schultz) Nordh. T Cir-H Myosotis ramosissima Rochel T E-As Myosotis scorpioides L. H Cir-H Pulmonaria officinalis L.* 8 H E Symphytum officinale L. H E Symphytum tuberosum L. G Ce Brassicaceae Alliaria petiolata (M. Bieb.) Cavara et Grande* 8 H E-As 54 Acta Biologica Slovenica, 61 (2), 2018 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Alyssum alyssoides (L.) L. T S-Eur Arabidopsis thalliana (L.) Heynh. T Cosm Arabis glabra (L.) Bernhardt H Cosm Arabis hirsuta (L.) Scop.* 8 H Cosm Brassica napus L. T Cul-ad Calepina irregularis (Asso) Thell.* 8 T E Capsella bursa-pastoris (L.) Med. H Cosm Cardamine bulbifera (L.) Crantz* 8 G E Cardamine pratensis L. H Cir-H ssp. dentata (Schult.) Celak Cardaria draba (L.) Desv G Cosm Coronopus squamatus (Forssk.) Asch. T Cosm Descurainia sophia (L.) Webb ex Parntl T E-As Diplotaxis muralis (L.) DC. T Cosm Diplotaxis tenuifolia (L.) DC. H Cosm Lepidium ruderale L. T E-As Rorippa amphibia (L.) Besser Hy E-As Rorippa sylvestris (L.) Besser H E-As Sinapis arvensis L. T Cosm Sisymbrium officinale (L.) Scop. T Cosm Thlaspi alliaceum L.* 8 T S-Eur Callitrichaceae Callitriche palustris L. Hy Cir-H SP Campanulaceae Campanula patula L. * 8 H E-As Campanula sibirica L.* 11 H Se-E Campanula trachelium L. ssp. trachelium* 7 H E-As DD Cannabaceae Humulus lupulus L.* 2 P E-As Caprifoliaceae Sambucus nigra L. P Cosm Viburnum opulus L. P E-As Caryophyllaceae Agrostemma githago L.* 2 T Cosm Arenaria serpyllifolia L. T Cosm Cerastium brachypetallum Pers. T S-Eur Cerastium glomeratum Thuill. T Cosm Cerastium semidecandrum L. T S-Eur Lychnisflos-cuculi L.* 8 H E-As Lychnis viscaria L. H E-As Myosoton aquaticum (L.) Moench. H E-As Petrorhagia prolifera (L.) P. W. Ball T E-As et Heywood Silene latifolia Poir. ssp. alba (Mill.) H E-As Greuter et Bourdet Silene otites (L.) Wibel H E-As Silene vulgaris (Moench) Garcke H E-As Stellaria media (L.) Vill. T Cosm Celastraceae Euonymus europaeus L. P E-As Rozac et al.: Flora of Kopacki rit Nature Park 55 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Ceratophyllaceae Ceratophyllum demersum L Hy Cosm Chenopodiaceae Chenopodium album L. T Cosm Chenopodium polyspermum L. T Cosm Chenopodium rubrum L. T Cosm DD SP Cichoriaceae Cichorium intybus L. H Cosm Crepis foetida L. ssp. rhoeadifolia (M. Bieb.) Celak. T Ee-P Hieracium caespitosum Dumort.* 8 H E-As Lactuca serriola L. H Cosm Mycelis muralis (L.) Dumort. H E-As Picris hieracioides L. H E-As Sonchus arvensis L. H Cosm Sonchus asper (L.) Hill T E-As Taraxacum officinale Weber H Cosm Tragopogon pratensis L. ssp. orientalis (L.) Celak. H E-As Tragopogon pratensis L. ssp. pratensis H E-As Clusiaceae Hypericum hirsutum L. H Cosm Hypericum perforatum L. H Cosm Convolvulaceae Calystegia sepium (L.) R. Br. H Cosm Convolvulus arvensis L. G Cosm Cornaceae Cornus mas L. P S-Eur Cornus sanguinea L. P E Corylaceae Carpinus betulus L. P Ce Corylus avellana L. P E Cucurbitaceae Echinocystis lobata (Michx.) Torr. et Gray11 T Cul-ad Cuscutaceae Cuscuta australis R. Br. 4 T S-Eur ssp. cesatiana* (Bertol.) Feinbrun Dipsacaceae Dipsacus fullonum L. H S-Eur Dipsacus laciniatus L.* 2 H E-As Dipsacus pilosus L H E-As Scabiosa ochroleuca L H E Euphorbiaceae Euphorbia amygdaloides L. Ch Ce Euphorbia cyparissias L. H E-As Euphorbia lucida Waldst. et Kit.* 1 H Ce Euphorbia palustris L. G Cosm Euphorbia salicifolia Host H Ee-P Euphorbia virgata Waldst. et Kit.* 1 H E-As Fabaceae Amorpha fruticosa L.11 P Cul-ad 56 Acta Biologica Slovenica, 61 (2), 2018 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Astragalus glycyphyllos L. H E-As Coronilla varia L. H E Galega officinalis L. H Ee-P Lathyrus hirsutus L.* 2 T S-Eur Lathyrus palustris L.* 2 H Cir-H DD SP Lathyrus pratensis L. H E-As Lathyrus tuberosus L. H E-As Lotus corniculatus L. H Cosm Medicago lupulina L. T Cosm Melilotus albus Medik. T E-As Melilotus officinalis (L.) Lam. H E-As Ononis arvensis L. Ch E-As Ononis spinosa L. Ch E Robinia pseudoacacia L.' P Cul-ad Trifolium campestre Schreber T Cosm Trifolium hybridum L. H S-Eur Trifolium patens Schreb.* 8 T S-Eur Trifolium pratense L. H E-As Trifolium repens L. H Cosm Vicia angustifolia L. T E Vicia grandiflora Scop. H Ee-P Vicia sativa L. T Cosm Fagaceae Quercus cerris L. P S-Eur Quercus robur L. P E Fumariaceae Corydalis intermedia (L.) Mérat* 8 G Ce Gentianaceae Centaurium pulchellum (Sw.) Druce T E-As Gentiana pneumonanthe L.* 1 H E-As EN SP Geraniaceae Erodium cicutarium (L.) L' Her. T Cosm Geranium dissectum L.* 1 T Cosm Geranium molle L.* 7 T Cosm Geranium robertianum L. T Cosm Haloragaceae Myriophyllum spicatum L. Hy Cosm Myriophyllum verticillatum L. Hy Cir-H Hippuridaceae Hippuris vulgaris L. Hy Cir-H EN SP Juglandaceae Juglans nigra L. P Cul-ad Juglans regia L.* 8 P Cul-ad Lamiaceae Ajuga genevensis L.* 8 H E-As Ajuga reptans L. H E-As Ballota nigra L. H E Calamintha sylvatica Bromf. H E Clinopodium vulgare L. H Cosm Galeopsis speciosa Mill. T E Galeopsis tetrahit L. T E-As Rožac et al.: Flora of Kopački rit Nature Park 57 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Glechoma hederacea L. H Cir-H Glechoma hirsuta Waldst. et Kit. H S-Eur Lamium amplexicaule L.* 7 T E-As Lamium maculatum L. H E-As Lamium purpureum L. T E-As Leonurus cardiaca L. H E-As Leonurus marrubiastrum L. H E-As Lycopus europaeus L. H E-As Mentha aquatica L. H Cosm Mentha arvensis L. H Cir-H Mentha longifolia (L.) Huds. H Cosm Mentha piperita L. H Cosm Mentha pulegium L. H E-As Mentha x verticillata L. H E Nepeta cataria L.* 10 H Cosm Prunella laciniata (L.) L. H S-Eur Prunella vulgaris L. H Cosm Salvia glutinosa L.* 7 H E-As Salvia nemorosa L.* 3 H Ee-P EN SP Salvia pratensis L.* 8 H E Scutellaria galericulata L. G Cir-H Scutellaria hastifolia L. G Se-E Stachys palustris L. H Cir-H Stachys recta L.* 8 G S-Eur Stachys sylvatica L.* 7 H E-As Teucrium scordium L. H E Thymus pulegioides L. Ch S-Eur Lentibulariaceae Utricularia vulgaris L. Hy Cir-H SP Loranthaceae Loranthus europaeus Jacq. P E-As Lythraceae Lythrum hyssopifolia L. T Cosm Lythrum salicaria L. H Cosm Malvaceae Abutilon theophrasti Medik.11 T Cosm Althaea officinalis L. H Cosm Hibiscus trionum L.* 6 T S-Eur EN SP Lavatera thuringiaca L.* 6 H E-As Malva sylvestris L. P Ce Menyanthaceae Nymphoides peltata (S. G. Gmelin) Kuntze Hy E-As Moraceae Morus alba L. P Cul-ad Morus nigra L. P Cul-ad Nymphaeaceae Nuphar lutea Sibth. et Sm. Hy E-As Nymphaea alba L. Hy E-As Oleaceae Fraxinus americana L. P Cul-ad Fraxinus angustifolia Vahl P S-Eur 58 Acta Biologica Slovenica, 61 (2), 2018 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Fraxinus pennsylvanica Marshall P Cul-ad Ligustrum vulgare L. P Ce Onagraceae Circaea lutetiana L. H Cosm Epilobium parviflorum Schreber* 3 H E-As Oxalidaceae Oxalis acetosella L. G Cosm Oxalis fontana Bunge H Cul-ad Papaveraceae Chelidonium majus L. Hy Cosm Papaver dubium L.* 2 T Cosm Papaver rhoeas L. T Cosm Phytolaccaceae Phytolacca americana L.I) G Cul-ad Plantaginaceae Littorella uniflora (L.) Asch.* 5 Hy E-As DD SP Plantago altissima L. H S-Eur Plantago lanceolata L. H Cosm Plantago major L. H E-As ssp. intermedia (Gilib.) Lange Plantago major L. ssp. major H Cosm Polygalaceae Polygala comosa Schkuhr* 8 H E-As Polygonaceae Polygonum amphibium L. G Cosm Polygonum arenastrum Boreau* 6 T Cosm Polygonum aviculare L.* 9 T Cosm Polygonum hydropiper L. T Cir-H Polygonum lapathifolium L.* 2 T Cosm Polygonum minus Hudson T Cosm Polygonum mite Schrank T E Polygonum persicaria L. T Cosm Reynoutria japonica Houtt.I) G Cul-ad Rumex conglomeratus Murray H Cosm Rumex crispus L. H Cosm Rumex hydrolapathum Hudson Hy E Rumex maritimus L. T E-As DD SP Rumex obtusifolius L. H Cosm Rumex palustris Sm. T E-As Portulacaceae Portulaca oleracea L.* 6 T Cosm Primulaceae Anagallis arvensis L.* 8 T Cosm Hottonia palustris L. Hy E-As EN SP Lysimachia nummularia L. H E Lysimachia vulgaris L. H E-As Primula vulgaris Huds. H S-Eur Ranunculaceae Caltha palustris L.* 8 H Cosm Clematis vitalba L. P E Consolida regalis S. F. Gray* 9 T S-Eur Rožac et al.: Flora of Kopački rit Nature Park 59 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Ranunculus acris L. H Cosm Ranunculus aquatilis L. Hy Cosm Ranunculus auricomus L. H E-As Ranunculus circinatus Sibth. Hy E-As Ranunculus ficaria L. G E Ranunculus flammula L. H E-As Ranunculus repens L. H Cosm Ranunculus sardous Crantz* 9 T Cosm Ranunculus sceleratus L. T E-As Ranunculus trichophyllus Chaix in Vill. Hy E Thalictrum lucidum L. H E Resedaceae Reseda lutea L. H Cosm Rhamnaceae Frangula alnus Mill. P Ce Rhamnus catharticus L.* 7 P E-As Rosaceae Agrimonia eupatoria L. H Cir-H Crataegus monogyna Jacq. P Ce Crataegus nigra Waldst. et Kit. P Ee-P Crataegus pentagyna Waldst. P Ee-P et Kit. ex Willd. Fragaria vesca L. H Cosm Geum urbanum L.* 7 H Cosm Malus sylvestris Mill.* 7 P Ce Potentilla anserina L. H Cosm Potentilla reptans L. H Med Potentilla supina L. T Cosm Prunus avium L. P E-As Pyrus pyraster (L.) Burgsd.* 10 P E-As Rosa canina L.* 2 P Cosm Rubus caesius L. P E-As Rubus plicatus Weihe et Nees P Ce Rubiaceae Cruciata glabra (L.) Ehrend. H E-As Cruciata laevipes Opiz H E-As Galium album Mill. H E-As Galium aparine L.* 2 T Cosm Galium mollugo L. H E-As Galium odoratum (L.) Scop.* 7 G E-As Galium palustre L. H E-As Galium verum L. H Cosm Salicaceae Populus alba L. P E-As Populus x canadensis Moench* 6 P Cul-ad Populus nigra L. P E-As Salix alba L. P E-As Salix caprea L. P E-As Salix fragilis L. P E-As Salix purpurea L. P E-As Salix triandra L. P E-As 60 Acta Biologica Slovenica, 61 (2), 2018 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Santalaceae Viscum album L. P E-As Scrophulariaceae Gratiola officinalis L. H Cosm Kickxia elatine (L.) Dumort. ssp. elatine T S-Eur DD Lathraea squamaria L.* 8 G E-As Limosella aquatica L. T Cir-H CR SP Linaria genistifolia (L.) Mill. H E-As Linaria vulgaris Mill. H E-As Lindernia procumbens (Krock.) Philcox T E-As VU SP Odontites vernus (Bellardi) Dumort.* 10 T E-As Pseudolysimachion longifolium (L.) Opiz H E-As EN SP Scrophularia nodosa L. H Cir-H Verbascum blattaria L. H Cosm Verbascum nigrum L. H E Verbascum phlomoides L. H E Veronica anagallis-aquatica L. H E Veronica austriaca L. H Ee-P Veronica catenata Pennell* 5 Hy Cir-H Veronica chamaedrys L. H E-As Veronica hederifolia L. T E-As Veronica peregrina L. T Cul-ad Veronica persica Poir.' T Cosm Veronica scutellata L. H E Veronica serpyllifolia L.* 8 H Cosm Veronica teucrium L. H E-As Simaroubaceae Ailanthus altissima (Mill.) Swingle*-' 2 P Cul-ad Solanaceae Datura stramonium L.:) T Cosm Physalis alkekengi L. H E Solanum dulcamara L. P Cosm Solanum nigrum L. T Cosm Tiliaceae Tilia cordata Mill.* 7 P E Tiliaplatyphyllos Scop.* 7 P E Trapaceae Trapa natans L. Hy Cosm NT SP Ulmaceae Ulmus laevis Pall. P Ce Ulmus minor Miller P E Urticaceae Parietaria officinalis L. H S-Eur Urtica dioica L. H Cosm Urtica kioviensis Rogow. H E Valerianaceae Valeriana officinalis L.* 3 H E-As Valerianella locusta (L.) Laterrade T Med Verbenaceae Verbena officinalis L. H Cosm Violaceae Viola alba Besser H S-Eur Rožac et al.: Flora of Kopački rit Nature Park 61 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Viola arvensis Murray* 7 T Cosm Viola elatior Fr.* 8 H E-As Viola hirta L. H E-As Viola odorata L. H E Viola reichenbachiana Jord. ex Boreau H E-As Viola tricolor L. T Cul-ad Vitaceae Vitis vinifera L. 2 P Cul-ad ssp. sylvestris (C. C. Gmel) Hegi* LILIOPSIDA (MONOCOTYLEDONAE) Acoraceae Acorus calamus L. Hy Cul-ad Alismataceae Alisma gramineum Lej. Hy E-As EN SP Alisma lanceolatum With. Hy Cosm Alisma plantago-aquatica L. Hy Cosm Sagittaria sagittifolia L. Hy E-As Amaryllidaceae Allium angulosum L.* 1 G E-As EN SP Allium scorodoprasum L. G Ee-P Allium vineale L.* 8 G Cosm Leucojum aestivum L. G E Asparagaceae Asparagus officinalis L.* 8 G Cul-ad Convallaria majalis L. G Cir-H Muscari botryoides (L.) Mill.* 8 G S-Eur Scilla bifolia L. G S-Eur Butomaceae Butomus umbellatus L. Hy E-As NT Colchicaceae Colchicum autumnale L.* 8 G Ce Cyperaceae Bolboschoenus maritimus (L.) Palla* 9 Hy Cosm NT Carex acuta L. Hy E-As Carex acutiformis Ehrh. Hy E-As NT Carex bohemica Schreb. H Cir-H CR SP Carex digitata L. H E-As Carex distans L. H E Carex divulsa Stokes H Cosm Carex elata All. Hy E Carex flacca Schreb.* 9 G Cosm Carex hirta L. G E-As Carex nigra (L.) Reichard G Cosm EN SP Carex pendula Huds. H E-As Carex remota L. H E Carex riparia Curt. G E-As VU SP Carex spicata Huds. H E-As Carex sylvatica Huds. H E Carex vesicaria L. G Cir-H VU SP Carex vulpina L. H E 62 Acta Biologica Slovenica, 61 (2), 2018 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Cyperus flavescens L. T Cosm VU SP Cyperus fuscus L. T E-As VU SP Cyperus glomeratus L.* 3 T E-As VU SP Cyperus longus L. Hy Cosm VU SP Cyperus michelianus (L.) Link T E-As VU SP Eleocharis acicularis (L.) Roem. et Schult. G Cosm Eleocharis ovata (Roth) Roem. et Schult. T Cir-H EN SP Eleocharis palustris (L.) Roem. et Schult. G Cosm Scirpus lacustris L. ssp. lacustris Hy Cosm Scirpus mucronatus L.* 2 Hy Cosm CR SP Scirpus pendulus Muhl.* 10 Hy Cul-ad Scirpus supinus L. T Cosm CR SP Hydrocharitaceae Elodea canadensis Michx.*- 1 9 Hy Cul-ad Elodea nuttallii (Planch.) H.St.John Hy Cul-ad Hydrocharis morsus-ranae L. Hy E-As Stratiotes aloides L.* 2 Hy E-As VU SP Iridaceae Iris pseudacorus L. G E-As SP Iris sibirica L. ssp. sibirica* 1 G E-As VU SP Juncaceae Juncus articulatus L G Cir-H Juncus bufonius L. T Cosm Juncus compressus Jacq. G Cosm Juncus effusus L.w H E-As Juncusinflexus L. H E-As Juncus tenuis Willd.I) H Cosm Lemnaceae Lemna gibba L. 11 Hy Cosm EN SP Lemna minor L. Hy Cosm Lemna minuta Kunth* 11 Hy Cosm Lemna trisulca L. Hy Cosm Spirodela polyrhiza (L.) Schleiden Hy Cosm Wolffia arrhiza (L.) Horkel ex Wimm. Hy Cosm VU SP Liliaceae Fritillaria meleagris L.* 8 G Med VU SP Najadaceae Najas marina L. Hy Cosm Najas minor All. Hy E-As Orchidaceae Anacamptispyramidalis (L.) Rich.* 3 G E NT SP Cephalanthera damasonium (Mill.) Druce G S-Eur NT SP Dactylorhiza incarnata (L.) Soo* ssp. incarnata 10 G E-As EN SP Epipactis helleborine (L.) Crantz* 8 G E-As SP Listera ovata (L.) R.Br.* 7 G E-As SP Orchis laxiflora Lam. ssp. palustris (Jacq.) Bonnier et Layens G E DD SP Orchis purpurea Huds.* 8 G E-As VU SP Rožac et al.: Flora of Kopački rit Nature Park 63 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Platanthera bifolia (L.) Rich.* 8 G E-As VU SP Platanthera chlorantha (Custer) Rchb.* 8 G E-As NT SP Poaceae Agrostis stolonifera L. H Cir-H Alopecurus aequalis Sobol. H E VU SP Alopecurus geniculatus L.* 3 H Cosm VU SP Alopecurus pratensis L. H E-As Dichanthium ischaemum (L.) Roberty H S-Eur SP Brachypodium sylvaticum (Huds.) H E-As P. Beauv. Bromus japonicus Thunb. T E-As Bromus squarossus L. T S-Eur Bromus sterillis L. T Cosm Calamagrostis epigejos (L.) Roth. H E Cynodon dactylon (L.) Pers. G Cosm Cynosurus cristatus L. H E Dactylis glomerata L. H E-As Echinochloa crus-galli (L.) P. Beauv. T Cosm Eleusine indica (L.) Gaertn*1 11 T Cul-ad Elymus caninus (L.) L. G E-As Elymus hispidus (Opiz) Melderis G S-Eur Elymus repens (L.) Gould* 10 G Cosm Festuca ovina L. H E Festuca pratensis Huds.* 8 H Cosm Festuca rubra L. H Cir-H Glyceriafluitans (L.) R.Br. Hy Cosm VU SP Glyceria maxima (Hartm.) Holmb. Hy E-As Holcus lanatus L. H E-As Hordeum murinum L. T Cir-H Koeleria macrantha (Ledeb.) Schult. H E-As Koeleria pyramidata (Lam.) P. Beauv. H E Lolium perenne L.* 8 H E Panicum capillare L.*J) 3 T Cul-ad Phalaris arundinacea L. G Cir-H Phleum paniculatum Huds. T Med SP Phragmites australis (Cav.) Hy Cosm Trin. ex Steud. Poa annua L. T Cosm Poa bulbosa L. H E-As Poa palustris L. H Cir-H NT Poa pratensis L. H Cosm Poa trivialis L. H E-As Sclerochloa dura (L.) P.Beauv T Med Setariapumila (Poir.) Schult. T Cosm Setaria viridis (L.) P.Beauv. T E-As Potamogetonaceae Potamogeton coloratus Hornem.* 5 Hy E Potamogeton crispus L. Hy Cosm Potamogeton gramineus L. Hy Cir-H Potamogeton lucens L. Hy Cir-H Potamogeton natans L.* 2 Hy Cosm Potamogeton nodosus Poir. * 10 Hy Cosm 64 Acta Biologica Slovenica, 61 (2), 2018 Investigated Floral Risk category / List of taxa locality Life form element Protection statusw Potamogeton perfoliatus L. Hy Cosm Potamogeton pusillus L. Hy Cosm Potamogeton trichoides Cham. et Schltdl. Hy E-As Stuckenia pectinata (L.) Börner* 5 Hy Cosm Sparganiaceae Sparganium erectum L. Hy E-As Sparganium erectum L. ssp. neglectum (Beeby) Schinz et Thell. Hy E-As Sparganium minimum Wallr. Hy E-As DD Typhaceae Typha angustifolia L. G Cir-H Typha latifolia L. G Cosm Typha laxmannii Lepech. G E-As CR SP Typha minima Funck G E-As CR SP From the taxonomic viewpoint, nine taxa (1.7%) belonged to ferns, while angiosperms were represented by 513 taxa: 381 (72.9%) belongs to dicotyledons and 132 (25.3%) to monocotyledons (Tab. 2). Table 2: Taxonomic analyses of the flora of Kopački rit Nature Park. Tabela 2: Taksonomske analize flore Naravnega parka Kopački rit. Taxonomic category Species and subspecies Genus Family Pteridophyta Magnoliopsida (Dicotyledonae) Liliopsida (Monocotyledonae) Total 9 381 132 522 6 226 63 295 6 72 18 96 The most diverse genera were: Carex (17 taxa), Ranunculus and Veronica (10 taxa each), Potamogeton (9), Polygonum (8) and Viola (7 taxa). The most frequent families were: Aster-aceae (43 taxa), Poaceae (40), Lamiaceae (34), Cyperaceae (30), Fabaceae and Scrophulariaceae (23 taxa each). Life-form analysis (Fig. 2a) showed that hemicryptophytes (39.3%) were dominant, followed by therophytes (23.8%), geophytes (12.6%), hydrophytes (12.5%) and phanerophytes (10.9%). Phytogeographical analysis (Fig. 2b), showed the prevalence of Eurasian floral element (32.8%), followed by Cosmopolites (27.4%) and European floral element (10.7%). Allochthonous flora was represented with 53 taxa (10.2% of the total flora) of which 12 (22.6%) were archaeophytes and 41 (77.4%) neophytes. The most of these taxa (22) have the North American origin, followed by 12 taxa of Asian origin (Fig. 3). Invasive alien plant species are represented by 26 taxa, which makes about 5% of the total flora. Rožac et al.: Flora of Kopački rit Nature Park 65 Figure 2: Life-form (A) and chorological spectrum (B) of the flora of Kopački rit Nature Park. Slika 2: Življenjska oblika (A) in horološki spekter (B) flore Naravnega parka Kopački rit. Figure 3: The ratio of geographical origin of allochthonous plants of Kopački rit Nature Park. Slika 3: Delež geografskega izvora alohtonih rastlin Naravnega parka Kopački rit. According to risk status assigned in the Red Book of Vascular Flora of Croatia (Nikolic and Topic 2005), 55 taxa (10.5% of the total flora) belongs to the following categories: critically endangered (6 taxa), endangered (13), vulnerable (17), near threatened (10), and 9 taxa as data deficient. Status of strictly protected species at the national level (Anonymous 2013b, 2016) was assigned to 53 taxa (10.2% of the total flora). One species, Marsilea quadrifolia is listed in Annex II of the European Union Habitat Directive (Anonymous 1992, 2013c). Discussion The vascular plant diversity of Kopački rit Nature Park makes 10.4% of the total 5,034 taxa (species and subspecies) recorded for the vascular flora of Croatia (Nikolic 2018). The floristic diversity of Kopački rit Nature Park is compared to that reported for selected protected areas in the Danube River basin (Tab. 3). Biological spectrum confirms the phyto-geographical position in the Pannonian sector of Central European Province, with hemicryptophytes indicating high plant resistance to the winter cold and adaptation to the moderate climate (Ellenberg 1988). For the comparison, therophytes (38.0%) 66 Acta Biologica Slovenica, 61 (2), 2018 and hemicryptophytes (33.0%) are dominant in the Danube Delta, due to transitional position of this region, eastern of the Danubial Province and western of the Pontic Province (Ciocarlan 2011). A higher portion of therophytes (23.8%) indicates warm, and periodically dry climate conditions, as well as an impact of the human disturbance, because this life-form is usual in anthropogenic habitats (Dobrovic et al. 2006). The agricultural land under intensive crop production (oilseed rape, wheat, barley, corn, sugar beet, sunflower and soybean) dominates in Baranja region (Kovacic et al. 2016) and cropland surrounds the western border of the Park. Percentage of hydrophytes (12.5%) is higher than 4% confirmed for the Baranja region (Panjkovic 1990). This reflects the ecological features of Kopacki rit as a large fluvial-marshy floodplain where an occurrence and spatial distribution of terrestrial, wetland and aquatic vegetation depends on the frequency, intensity and duration of floods, and drought periods. The dominance of Eurasian floral element (32.8%) corresponds to 31.0% for the Baranja region (Panjkovic 1990) and 28.0% for the Danube Delta (Ciocarlan 2011). The percentage of cosmopolites (27.4%) is much higher than in the Baranja region (6.2%), and the Danube Delta (8.3%). Oppositely, the percentage of the Central European floral element is much higher in the Baranja region (20.9%) than in Kopacki rit Nature Park (2.9%). Percentage of European floral element is higher in the Danube Delta (14.0%). The allochthonous flora includes 53 taxa, which makes 8.5% of 624 taxa registered for the allochthonous flora of Croatia. Invasive alien plants count 26 taxa or 34.7% of 75 taxa registered in the Croatian flora (Nikolic 2018). The presence of alien plants is higher (13.4%) in Donau-Auen National Park (Drescher and Magnes 2002), and lower (3.1%) in Special Nature Reserve Gornje Podunavlje (Panjkovic and Stojsic 2001), and Danube Delta Biosphere Reserve with 5.4% (Mihai et al. 2011). The richer allochthonous flora shows disturbance intensity caused by anthropogenic activities. Wet meadows from the vegetation alliance Cnidion dubii are still present in the area of Kopacki rit Nature Park, but under the high risk of extinction. This was confirmed by recording the presence of taxa: Allium angulosum, Euphorbia lucida, Gentiana pneumonanthae, Iris sibirica ssp. sibirica and Pseudolysimachion longifolium, as diagnostic species for this habitat type listed in Annex I of the EU Habitats Directive under the code: 6440 Alluvial meadows of river valleys of the Cnidion dubii (Anonymous 1992, 2013c). Knowledge on the diversity of orchid family (Orchidaceae) expands from two previously re- Table 3: A comparison of the floristic diversity between Kopački rit Nature Park and selected protected areas in the Danube catchment area. Tabela 3: Primerjava florne raznovrstnosti Naravnega parka Kopački rit z izbranimi zavarovanimi območji v Donavskem porečju. Protected area (Country) Number Reference of taxa Kopacki rit Nature Park (Croatia) 522 Lonjsko Polje Nature Park (Croatia) 550 Gugič (2008) Donau-Auen National Park (Croatia) 838 Drescher and Magnes (2002) Gornje Podunavlje Special Nature Reserve (Serbia) 1,000 Panjkovic et al. (2000) Derdap National Park (Serbia) 1,013 Petrič et al. (2010) Rusenski Lom Nature Park (Bulgaria) 877 Stoyanov (2005) Danube Delta (Romania) 985 Ciocarlan (2011) Danube Delta Biosphere Reserve (Romania) 1,215 Mihai et al. (2011) Rožac et al.: Flora of Kopački rit Nature Park 67 ported taxa (Cephalanthera damasonium, Orchis laxiflora ssp. palustris) to currently known nine taxa. During the field surveys, following seven taxa were discovered: Anacamptys pyramidalis, Dactylorhiza incarnata ssp. incarnata, Epipactis helleborine, Listera ovata, Orchis purpurea, Platanthera bifolia and Platanthera chlorantha. All taxa of the Orchidaceae are strictly protected species in Croatia. The macrophyte diversity in Kopacki rit Nature Park comprises 158 taxa (30.3% of the total flora), which exceeds the number of only seven taxa recorded in the Danube main channel, and 37 taxa recorded in water bodies along the right bank in the Croatian reach of the Danube River (Ozimec and Topic 2018). Stressors and threats to the flora of Kopacki rit Nature Park are natural and anthropogenic. In recent decades, more frequent fluctuations in flooding intensity of the Danube River, and extension of a dry season affects to reduction in size of the inundated area. Accumulation of suspended solids and sediment in sidearms and channels disrupt hydrological connection and initiate the natural succession processes. Abandoned land, as well as habitats overgrown with shrubs or herbaceous ruderal vegetation under the natural succession, supports the colonisation and dispersal of the invasive alien plant species, which can threaten the native flora. Stressors such as air, soil and water pollutants, pests and pathogens, invasive species, fire, storms, land management and visitor use have a harmful impact at some point on plants and their habitats. Conclusions 1. The diversity of vascular plants in Kopacki rit Nature Park, with 522 currently known taxa, confirms significant ecological values of this floodplain area situated in the middle course of the Danube River. 2. The flora is characterised by high percentage of hemicryptophytes and therophytes, as well as of Eurasian floral element and Cosmopolites. 3. Regarding the plant conservation, 53 taxa have a status of strictly protected species, and 55 taxa are included in the Red Book of Vascular Flora of Croatia. 4. Allochthonous flora is represented with 53 taxa, among which 26 are invasive alien plant species. 5. Comprehensive knowledge on plant diversity is an important tool for planning and implementation of activities in conservation of rare and threatened plants and their habitats in Kopacki rit Nature Park. Povzetek Naravni park Kopački rit se nahaja v severovzhodni Hrvaški, na območju sotočja Donave in reke Drave. Park pokriva območje 231 km2 in se nahaja na nadmorski višino od 78 do 86 m. Glede na fitogeografsko razdelitev sodi območje v evrosibirsko-severnoameriško regijo, panonski sektor srednjeevropske province. Zaradi izjemne biološke in ekološke vrednosti tega poplavnega območja v srednjem toku reke Donave, je območje od leta 1967 zaščiteno. Floristične študije na območju Naravnega parka Kopački rit so bile v preteklosti razdrobljene. V prispevku so zbrani literaturni podatki in rezultati terenskih raziskav, ki so bile izvedene v obdobju od leta 2010 do leta 2018. V Naravnem parku Kopački rit je bilo ugotovljenih 522 taksonov vaskularnih rastlin, kar potrjuje ekološko vrednost tega poplavnega območja, ki se nahaja v srednjem toku reke Donave. Za floro je značilen visok odstotek hemikriptofitov in terofitov, ter evrazij skih flornih elementov in kozmopolitov. Kar 53 taksonov ima status strogo zaščitenih vrst, 55 pa jih je vključenih na Rdeči seznam flore Hrvaške. Tujerodne rastline so zastopane s 53 taksoni, med katerimi je 26 invazivnih tujerodnih rastlinskih vrst. V Naravnem parku Kopački rit so prisotni številni naravni in antropogeni pritiski. V zadnjih desetletjih so pogoste spemembe vodostajev reka Donave in podaljševanje suhe sezone kar vpliva na zmanjšanje obsega poplavljene površine. Kopičenje usedlin v stranskih rokavih in kanalih moti hidrološko povezavo med različnimi predeli kar pospešuje sukcesijske procese. Opuščena 68 Acta Biologica Slovenica, 61 (2), 2018 zemljišča ter habitati poraščeni z grmovjem ali zeliščno ruderalno vegetacijo, podpirajo kolonizacijo in razširjanje invazivnih tujerodnih rastlinskih vrst, ki lahko ogrozijo domačo floro. Predstavljeni izsledki predstavljajo pomembno izhodišče za načrtovanje in izvajanje dejavnosti ohranjanja redkih in ogroženih rastlin ter njihovih habitatov v Naravnem parku Kopački rit in drugih podobnih območjih. References Acknowledgements Management and staff from the Public Institution Kopacki rit Nature Park supported research and provided technical assistance for the field activities. Anonymous, 1992. Council Directive 92/43/EEC of 21 May 1992 on the Conservation of Natural Habitats and of Wild Fauna and Flora. Official Journal of the European Communities L 206, 35. Anonymous, 1999. Zakon o Parku prirode „Kopački rit". Narodne novine, 45. Anonymous, 2006. Odluka o donošenju Prostornog plana Parka prirode „Kopački rit". Narodne novine, 24. 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