Eva Uherčíková’s research while affiliated with Slovak Academy of Sciences and other places

This paper aims to describe a vegetative cover of the Nature Reserve Hetméň (located near the village of Lehnice, the Žitný Ostrov Island, Danube Lowlands, SW Slovakia) covering an area of 14.7 hectares. During the field study we have recorded 16 phytosociological relevés and the presence of 104 species of vascular plants. In terms of species composition and structure, this isolated woodland amidst intensively managed cropland areas represents a hardwood flo-odplain forest of the subassociation Fraxino pannonicae-Ulmetum convallarietosum Jurko 1958 and Fraxino pannonicae-Ulmetum populetosum (Jurko 1958) Džatko 1972. The woodland is of secondary origin since it was established by an artificial planting on and around a previously isolated eolian dune. Despite its partially altered tree-species composition (mainly due to abundant Robinia pseudoacacia and Celtis occidentalis) and the common occurrence of additional non-native and invasive species, we find the studied territory very valuable regarding vegetation. In addition, rich occurence of Lithospermum purpurocaeruleum demonstrates the character of former association Ulmeto-Quercetum lithospermetosum Jurko 1958.

This study is focused on a cutoff palaeomeander of the Rudava River (SW Slovakia). Along its middle reach, Rudava passes through the extensive plain of Quaternary eolian sands covered with Scots Pine woodland. Specific landforms-semi-circled cut-bluffs (wagrams) are commonly found on either side of the river valley. They have been triggered by a meandering river in contact with both lower terraces and sand dune pseudoterrace and postgenously shaped by mass wasting. The left-bank palaeomeander and cut-bluff at river kilometre 13.2 is one of the most completely evolved and, until today, the best-preserved landforms of this kind. A palaeoecological study of the palaeomeander infill (two cores) combined with a digital elevation model, AMS radiocarbon dating, cartographic data analysis and a survey of present-day vegetation suggest the river meander was most probably cutoff in the 18th Century. Due to the flow hydrological regime, meandering dynamics at this reach is relatively slow. Numerous springs and seepage along the south edge of the river valley play an important role in the initiation and evolution of cut-bluffs. Also, at the site under study, such spring draining into the Rudava River has significantly contributed to the present-day variability of local soils, wood and marsh habitats. According to plant macrofossil records and ecogroups-based vegetative macrozones a riparian landscape in the time of meander abandonment and earlier was much more open and with a markedly human impact. Probably upon the pastureʼs decline, the Holocene flood-plainʼs adjacent reach was completely reforested until the mid-19th Century. Current hardwood alluvial woodland (of the association Ficario vernae-Ulmetum campestris) originated in 1916 mainly from natural and perhaps artificial regeneration.

This study focuses on the defunct historical wetland habitat located at the interface of Carpathian and Pannonian phytogeographical regions in what is now central part of Bratislava, Slovakia. S. Lumnitzer in his Flora Posoniensis (1791) reported interesting marsh species from the then location "unter dem Pazenhäusel", such as Pedicularis palustris, Peucedanum palustre, Eriophorum angustifolium, Dactylorhiza majalis. Using botanical and geological data, historical maps, field survey and radiocarbon dating, we have reconstructed the location, character and initial area of a historical wetland, evidenced by abovementioned taxa, but also controlling factors which had determined its existence. Human-dependent fen-meadows habitat, probably with a plant community of Caricetum goodenowii, began to decline upon draining in 1890s and eventually fell victim to urban development. Palaeoecological record from a small forest wetland-remnant of former marsh at the margin of Horský park (= renowned urban forest) has documented a relatively young age and co-alluvial character of deposits, although the examined 80 cm deep core extends back to the 17 th century. In total 727 plant seeds, belonging to at least 44 plant taxa document succession (macrofossil zones MZ 1-3) and environmental changes over time.

Jarovská Bažantnica pheasantry - an unique natural piece and cultural and historical monument on the Slovak-Austrian border. Protected Site Jarovská bažantnica is an unique piece of close-to-nature Danubian hardwood floodplain forest, surrounded by intensively cultivated fields. Due to its location near the Slovak-Austrian border it has long been inaccessible for public and neglected as a part of former „Iron Curtain“. However, this forest has an interesting history: as early as 1730s it was adapted by local landlord for recreation and hunting. In this paper we present some new findings from interdisciplinary oriented study of this valuable reserve. Phytosociological research (based on ecological analysis of 17 relevés) brings new data on syntaxonomy, species diversity and life forms of local plants, with special attention paid to dendrological values of the area and local abundant presence of Bladdernut (Staphylea pinnata) in the shrub layer. The territory is also interesting as to the soilscape: over time, original Danubian Fluvisols have developed here into the current mollic Haplic Chernozems and Mollic Fluvisols. Both phytosociological and soil survey data point to the fact that site conditions were moister in the past. Over the past two centuries they had gradually developed towards current relatively dry types of hardwood forest communities of Fraxino pannonicae – Ulmetum convallarietosum to carpinetosum. Several invasive species (including Ailanthus altissima, Parietaria officinalis, Solidago gigantea or Imptaiens parviflora) represent a serious threat to native vegetation.

In this paper we present the results of interdisciplinary study focused on mineral alluvial soil which has developed from calcareous fluvial silty loams of former Danube River side channel (location: Devín Gate, Bratislava, former Pečňa Island, SW Slovakia). Paleoenvironmental reconstruction is based on fossil molluscan assemblages and spans more than ± 250 years of local site development and hydroseral succession. Recognised changes of both water regime and floodplain habitats are based on 4 local malacozones that correspond well with the evidence of island development and land use in the past (17 – 19th century historical maps, written accounts, floristic data, respectively). In total 416 subfossil shells of Mollusca belonging to 33 taxa provide us with a picture of how the early side channel of parapotamal type gradually changed into the isolated waterbody (plesiopotamal type) and eventually transformed itself into a narrow field depression covered by forest. They also characterise a different sedimentary settings (recent vertical accretion of overbank silty loams vs. earlier subaquaceous deposition in abandoned channel). Fosssil molluscan assemblages also illustrate a change in local habitat from 1. shallow marsh with reed bed, through 2. an initial hygrophilous Salici-Populetum woodland and finally into the 3. current mesophilous type of bottomland woodland (Fraxino pannonicae – Ulmetum type). Over a study period, due to the Danube channel modifications and regulation the overbank sediment delivery decreased and became only episodical. Drop in mean groundwater levels coupled with channelisation and elimination of floods by protective levees also explains a soil successsional pathway from initial gleysol, intermediate gleyic fluvisol until the current fluvisol. Although fossil molluscan asseblages may also contain significant proportion of allochthonous shells, in our case they mainly reflect local habitats and even the presence of an agrarain enclave which existed on the island in the past.

Human alteration of watercourses is global phenomenon that has had significant impacts on local ecosystems and the services they provide. Monitoring of abiotic and biotic changes is essential to mitigating long-lasting effects, and the 23-year dataset from the Gabčíkovo Waterworks provided a rare opportunity to assess the impact of groundwater regimes on vegetation. The main aim of this study was to describe the effect of the Gabčíkovo Waterworks on vegetation structure and species composition of the adjacent riparian floodplain forests over the past 23 years. The results are based on studies of three permanent monitoring plots (PMPs) located in the Danube inland delta – two outside (PMP 1 and 3) and one (PMP 2) fully under the influence of the artificial supply system. Our results demonstrate that the Danube inland delta was negatively affected by the Gabčíkovo construction, particularly for sites outside of the artificial supply system. There was a significant decrease in soil moisture and increase in nitrogen at both external PMPs (1 and 3). Alter soil conditions were accompanied by negative changes in plant species composition demonstrated by decreases in the number of typical floodplain forest species that are characteristic for the alliance

Treatment of the genus Persicaria for the Flora of Slovakia.

This paper examines alluvial forested swamps of 6 paleomeanders of the former Dudváh river (at Žitný ostrov island, SW Slovakia). Cluster analyses, Twinspan and gradient analysis (DCA) have been adopted to analyse material of 16 phytosociological relevées and a total of 98 plant species obtained in the course of 2005–2007 seasons. Based on these analyses, examined stands were subdivided into three major groups. First group (2 phy-tosociological relevés) is represented by poplar monocultures (Populus × canadensis), second (7 relevés) by willow-poplar stands with Populus × canescens, and the third one (7 relevés) by predominantly willow stands with Salix alba and S. fragilis on rather moist sites at the depression bottoms. All examined forests are of secondary origin. They occupy areas of former marshes, which had been partially drained since the early 19th century. Some stands were established naturally, others were intentionally planted for being used as pollard trees. Some species tolerating higher soil salinities (Atriplex prostrata) also occur in the groundlayer vegetation. Today, studied forests represent an important landscape elements in the almost completely deforested agricultural landscape , providing suitable habitats for local flora and fauna. These forest are also valuable as being still free of some common invasive and neophytic tree and plant species (as Negundo aceroides, Aster lanceolatus etc.). ÚVOD Podľa údajov historických listín a najstarších máp v 13. storočí Čalov, t. j. stredoveký Malý Dunaj neústil do Váhu pri Kolárove ako dnes, ale vlieval sa do Dunaja pri Čičove. Územie dnešného dolného Žitného ostrova v tom čase ešte tvorilo samostatnú geografickú jednotku, tzv. Vágköz (Medzivažie alebo Privažie). Dominantnými tokmi tohto územia, administratívne patriaceho k zázemiu komárňan-ského hradu, boli Váh a paralelne s ním tečúci Dudváh, vtekajúci doň juhovýchodne od dediny Čalo-vec. Vágköz sa stal súčasťou zväčšeného Žitného ostrova až v dôsledku závažných zmien koryta pri-bližne po roku 1378. Ich výsledkom bol postupný vznik nového, 16 km dlhého úseku Malého Dunaja na trase Topoľníky – Kolárovo (PIŠÚT 2006). Zmenou toku Malého Dunaja sa zároveň začalo postup-né zanášanie zvyšku koryta odrezaného Dudváhu, ktorý však bol periodicky prietočný ešte v 18. sto-ročí. Zvyšky jeho odstaveného koryta v dĺžke najmenej 24 km, ako aj viacero generácií zazemnených paleomeandrov Dudváhu možno dobre sledovať na leteckých snímkach, podrobných základných ma-pách územia, ale podnes aj priamo v teréne. V súčasnosti prebieha v rámci grantov VEGA 2/5016/25 a 2/5014/25 výskum vegetácie a malakocenóz biotopov na 6 km dlhom modelovom úseku bývalého koryta Dudváhu a jeho paleome-androv SZ od obce Čalovec. Práve na tieto staré riečne formy sa dnes totiž viažu cenné fragmenty pôvodných a poloprirodzených spoločenstiev v poľnohospodársky intenzívne využívanej a dnes tak-mer úplne odlesnenej krajine Žitného ostrova. Predmetom výskumu je aj paleoekologická analýza vrchnej časti sedmentárnej výplne zaniknutého meandra pri obci Štúrová, vrátane analýzy peľov (pozri BŘÍZOVÁ et al., in KRIŽOVÁ E., UJHÁZY K. (eds.) 2007). Staré meandre Dudváhu majú zväčša charakteristický tvar podkovy (" oxbow lakes "). Dnes sú tak-mer úplne zazemnené, t. j. nachádza sa v nich len niekoľko malých otvorených vodných plôch. Tieto jazierka sú zväčša sekundárneho pôvodu, boli vybagrované po druhej svetovej vojne kvôli odberu vody na zavlažovanie, prípadne slúžia ako napájadlá pre zver. Väčšiu časť plochy dien meandrov po-krývajú plošne rozsiahle, súvislé porasty trste a vysokých ostríc (Phragmitetalia Koch 1926), mozai-kovite sa vyskytujú aj spoločenstvá s dominanciou taxónov Bolboschoenus maritimus agg. a Glyceria aquatica. Uvedené porasty fytocenologicky podrobne charakterizovala KUBALOVÁ (2006). Podľa výsledkov paleoekologickej analýzy paleomeandra " Štúrová " boli tieto riečne formy odre-zané prirodzenou cestou už v období staršieho subatlantika, resp. ešte v strednom holocéne. Keďže " Pradudváh " mal v tom období ešte odlišné hydrologické parametre od moderného Dudváhu, korytá uvedených paleomeandrov sú výrazne širšie (30–60 m). Na rozdiel od zvyškového koryta moderného KRIŽOVÁ, E., UJHÁZY, K. (eds.) 2007: Dynamika, stabilita a diverzita lesných ekosystémov. TU vo Zvolene, Zvolen, p. 217–225; ISBN 978-80-228-1821-6 217

This article presents evaluation of long-term (1990–2004) stationary research on a forest phytocoenosis with the dominant tree species Populus × canadensis in the area affected by hydropower water structures Gabčíkovo on the Danube river. In the first three years of monitoring, where natural flooding occurred, species diversity was low, the structure and ecological proportion of a phytocoenosis were stabilized in an observed adult stand in rotation age. After clear-cutting and reforestation all the indicators changed (trends of parameters were statistically tested). An average of diversity increased 2.5 times, an intensive plants turnover was continuing during two years, and there was quantity of spreading of synanthrophyte, helipohyte, and nitrophilous herbs (species). After oscillating of ecological parameters (light, temperature, continentality, soil moisture, soil reaction, soil nitrogen), like forms and the species diversity were decreased in indicators, as well as a decline of heliophyte, synanthrophyte, and nitrophilous species. Formation of vegetation after 6 years of reforestation gradually tends to reach the state in the 90s. A tree layer was formed and herb understory was growing in mosaic.