MENDELNET 2016

INVASIVE PLANT SPECIES IN THE ACCOMPANYING VEGETATION OF THE RIVER

MICHAELA BENCOVA, JANA NOZDROVICKA, VERONIKA SELECKA, JOZEF TAZKY Department of Ecology and Environmental Sciences Constantine the Philosopher University in Nitra Tr. A. Hlinku 1, 949 01, Nitra SLOVAK REPUBLIC [email protected]

Abstract: This paper focuses on the evaluation of the species composition of accompanying vegetation adjacent to water flow in the of the Upper and species diversity among communities attacked by invasive species and non-invasive communities. The research was carried out in the vegetation period during the years 2015 and 2016 on the 10 km long section with 48 phytocenological relevés. The results indicate that there is a high concentration of researched species in the area, which progressively push out the original, natural vegetation. A total of 133 plant species were recorded 111 species in non-invasive vegetation and 104 species in invasive vegetation, 78 species were the same in both types of relevés. The species with the highest average coverage were the following invasive taxa: Helianthus tuberosus, Solidago canadensis and Amaranthus retroflexus. The non-invasive species were: Solanum nigrum, Urtica dioica, Rubus caesius and Humulus lupulus. KeyWords: invasive plant species, the Nitra river, the Slovak Republic

INTRODUCTION Invasive plant species cause problems and have negative impact on flora and fauna almost all over the world. They are one of the reasons for the change in the abiotic environment, and they affect human health and national economies (Křivánek 2006). The term "negative impact" conceals the suppression of native species in competition for resources (Melgoza et al. 1990), reduction of habitats, increased groundwater extraction and its subsequent lack for other species. There are also other changes in the hydrological regime, increased sedimentation and a subsequent change of rhythm to the whole ecosystem, e.g. riparian vegetation (Zavaleta 2000). Each non-native species changes the composition of natural diversity in a certain way. On the one hand, the introduction of non-native species can increase the overall number of species occurring in a particular place – at least in the short term. On the other hand, in the long term it will lead to a reduction in species diversity (the number and abundance of species). Another possibility is that it also leads to the displacement of native species from habitats or regions and to a total change in natural ecosystems (Shine et al. 2000, Nentwig 2014). On a municipal level, the crowding out of native plant species is a phenomenon resulting from the dominance of invasive plants, which prevail in contaminated locations. In general, the plant invasion causes homogenization of flora in which the originally different phytogeographic units become similar due to the massive invasion (Hejda and Pyšek 2006). In his study of invasive species of the Czech flora, Pyšek et al. (1998) indicates that after settlements, the habitats connected with still standing and running water are places with the highest representation of non-native species. Some authors consider habitats along rivers are more prone to invasion. It is justified by the disturbance occurring in these areas. Because of this disturbance, these communities are receiving higher quantities of available resources (Stohlgren et al. 1998).

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The aim of this paper is to assess the impact of invasive plant species on the composition and nature of the infested habitats, and to ascertain what the subsequent changes are to the composition of the community.

MATERIAL AND METHODS Study area The Nitra river rises on the southern slopes of the Malá Fatra Mts. After passing the Podunajská pahorkatina Upland it flows into the Váh river in the area of the Podunajská rovina Plain to the north of the city of Komárno. The flow length is 196.7 km and the total area of the river basin is about 5 144 km2 (Mazúr and Lukniš 1980, Porubský 1991).The area belongs to the basin of the Nitra river with a left tributary of the Handlovka river and to the upland-lowland regions with a rain-snow runoff regime (Šimo and Zaťko 2002). The defined part of the river is 10 river kilometres in length, and passes through cadastral territory of town and the villages Opatovce nad Nitrou, Diviacka Nová Ves and Zemianske Kostoľany (Figure 1). Figure 1 Location of the study area in the Slovak Republic (Bencová 2016)

Methodology of work The area of interest chosen was a 10 km long section from the confluence of the Nitra river with the Handlovka river (48° 44' 47.14" N, 18° 33' 32.70" E), up to the trigger point of the Zemianske Kostoľany village cadastre (48° 40' 42.27" N, 18° 30' 56.28" E). In this area a part of the river had transferred to a new river bed due to lignite mining. Also, settlements and a large number of cultivated areas occur in the area, where disturbance provides appropriate conditions for the occurrence of invasive species. During the years 2015 and 2016, 24 pairs of phytocenological relevés were recorded on an area of 4 x 4 metres. Each pair had one relevé per locality with a minimum of 60% coverage of invasive species and in the nearby non-invasive vegetation. Non-invasive areas were selected to represent the same habitat conditions as the habitat conditions of invasive areas (Hejda and Pyšek 2006). Individual invasive plant species have also appeared in the relevés of non-invasive areas because it was difficult to find areas with the total absence of their occurrence. The areas of comparison were selected on the basis of the following criteria: (a) locations are strongly attacked with invasive species, while populations are homogeneous (b) non-invasive cover is linked as far as possible on the attacked localities in order to maintain the same habitat conditions of the environment (altitude, orientation, ... etc.). The presence of the species was evaluated on the basis of the Braun-Blanquet scale coverage (van der Maarel 2005):

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r – rare species, + – occasional species, coverage is negligible, coverage ˂ 1%, 1 – coverage from 1 up to 5%, 2 – coverage from 5 up to 25%, 3 – coverage from 25 up to 50%, 4 – coverage from 50 up to 75%, 5 – coverage more than 75%. Invasive taxa were selected and mapped according to Gojdičová et al. (2002): category 1 – invasive taxa and category 2 – potential (regional) invasive taxa. Invasive relevés were realized in the vegetation of the following species: Helianthus tuberosus, Solidago canadensis, Impatiens parviflora, Tanacetum vulgare, Fallopia japonica, Fallopia x bohemica and Robinia pseudoacacia. The key for determination of plants was used for verifying the taxa of vascular plants (Dostál and Červenka 1991, 1992). The nomenclature of taxa has been unified according to the work of Marhold and Hindák (1998). The relevés were processed in Excel and subsequently in JUICE 7.0 (Tichý 2002), with which we calculated the average coverage of species and Shannon diversity index H´. Subsequently we calculated the evenness index by using the formula: Hʹ/In S, where S represents the number of species (Hejda and Pyšek 2006). The obtained data was processed in the CANOCO 4.0 program (Ter Braak and Šmilauer 2002), where DCCA (Detrended Canonical Correspondence Analysis) and RDA (Redundancy Analysis) analyses were carried out. A total number of 499 permutations were calculated in the Monte-Carlo test. Visualization was carried out using the CanoDraw program. The relation between invasive and non-invasive relevés was tested using the STATISTICA program (StatSoft Inc. 2007).

RESULT AND DISCUSSION In the study area through the 48 phytocenological relevés we discovered the presence of 133 plant species. Data about species abundance and value indexes was processed by DCCA analysis. On the basis of DCCA analysis, we found that the length of gradient was 2.534 therefore in the next step we used RDA analysis (Redundancy Analysis). The resulting values were visualized through CanoDraw (see Figure 2). The diagram shows only species with more than 10% variability in the data. Figure 2 RDA ordination diagram expressing relation between data and environmental variables Legend: Agri eup – Agrimonia eupatoria, Achil mil – Achillea millefolium, Cent jac – Centaurea jacea, Cich int – Cichorium intybus, Clem vit – Clematis vitalba, Euph cyp – Euphorbia cyparissias, Gali apa – Galium aparine, Heli tub – Helianthus tuberosus, Lotu cor – Lotus corniculatus, Odon vul – Odontites vulgaris, Past sat – Pastinaca sativa, Phra aus – Phragmites australis, Plan lan – Plantago lanceolata, Poa pra – Poa pratensis, Poly avi – Polygonum aviculare, Rubu cae – Rubus caesius, Sali alb – Salix alba, Samb ebu – Sambucus ebulus, Tara sec – Taraxacum sect. Ruderalia, Trif rep – Trifolium repens, Urti dio – Urtica dioica.

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For better differentiation, invasive relevés are represented by a blue triangle and non-invasive relevés are represented by a red triangle. The diagram shows the dependence between species, relevés and environmental variables. Relevés realized in areas of invasive vegetation were displayed in the opposite direction to the growing diversity of the relevés, while Helianthus tuberosus, Sambucus ebulus and Rubus caesius had the largest variability. The relevés located in the negative part of the diagram showed the greatest diversity and species richness. Ruderal and field species prevailed here as Trifolium repens, Plantago lanceolata and Clematis vitalba. We used the Monte-Carlo permutation test for evaluating environmental factors. We found following values of Shannon-Wiener Index: P-value = 0.002, F-ratio = 2.29; evenness Index: P-value = 0.004, F-ratio = 1.71. This means that both variables have a significant impact on the variability of displayed data, while both of the factors according to RDA analysis explain 8% of the overall variability. In the invasive relevés, the average occurrence of species was 14.41 species per relevé and in non- invasive it was 16.45. The difference in the number of species between the relevés is not too large. This may be due to the fact that some relevés were made in peripheral areas of invaded vegetation where the competitive struggle is not so significant. The average coverage of species in every relevé was assessed using the JUICE program. The species selected as the core taxa for creating the invasive relevés (that is, they had more than a 60% coverage in invasive vegetation) were removed from the table (Table 1). They were the following: Helianthus tuberosus, Solidago canadensis, Impatiens parviflora, Tanacetum vulgare, Fallopia japonica, Fallopia x bohemica and Robinia pseudoacacia. Out of them, the following species had the highest coverage in the area: H. tuberosus (inv. relevés: 50.9%, non-inv. relevés: 2.3%) and S. canadensis (inv. relevés: 37.4%, non-invasive relevés: 3%).

Table 1 Comparison of average coverage of selected species (˃ 10% in one category) Species of plant Life form Invasive relevés Non-invasive relevés Amaranthus retroflexus AH 32.5 - Ambrosia artemisiifolia AH 13 2 Brachypodium sylvaticum PG 3 13 Cuscuta epithymum AH - 13 Echinochloa crus-galli AH 3 20 Fallopia convolvulus AH - 13 Humulus lupulus P 9.6 15.8 Jacea pratensis P 13 3 Lysimachia nummularia P 13 2 Phragmites australis PG - 13 Rubus caesius S 7.9 13.4 Salix alba T 3 10.5 Solanum nigrum AH 38 3 Swida sanguinea S 6.3 13 Legend: AH – annual herb, PG – perennial grass, P – perennial, S – shrub, T – tree (Dostál and Červenka 1991, 1992) The data shows that of the invasive relevés the species with the highest average coverage was Echinochloa crus-galli, which is the characteristic species of roots and fallow lands. This species also occurred in invasive relevés although its coverage here has dropped to 3%. The loss of coverage for the species Humulus lupulus, Rubus caesius or Salix alba is also visible. The opposite effect was observed for species Solanum nigrum and Amaranthus retroflexus, where coverage was noticeably higher in invaded

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vegetation (vegetation attacked by invasive species). They appear as ordinary weeds in fallow lands and disturbed areas that are typical habitats for the invasive species. A. retroflexus is classified as a potentially invasive taxon. The relation between invasive and non-invasive types of relevés was subsequently tested in the STATISTICA program (see Figure 3). The hypothesis H0 was specified: coverage of individual types in invasive and non-invasive relevés do not differ-pα = 0.05. Since the graph shows, that p is greater than pα, it means that a given hypothesis cannot be rejected at the 95% confidence level. The value of the standard deviation for invasive relevés is 10.75% and for non-invasive relevés is 3.98%. Figure 3 Expression of the relation between invasive and non-invasive relevés

Legend: KW = Kruskal-Wallis test (difference between average values – the outliers were turned off), Conf. interv. – confidence interval, invaded – plant communities with invasive species, non-invaded – plant communities without invasive species

CONCLUSION Watercourses with their accompanying vegetation represent in their natural form an extremely important landscape element, which forms an ecologically significant landscape segment. Riparian vegetation is an important element for the ecological stability of the landscape, where it forms important biocorridors and sometimes refuges for fauna in the surrounding mostly agricultural land (Benčať and Pažitný 2007). Phytocenological relevés were located so as to document the nature of the accompanying vegetation of the Nitra river. They represent the vegetation and ecotone of riparian vegetation, as well as the edges of fields and ruderal habitats affected by humans to varying degrees. In the study area we recorded the presence of 133 plant species, out of them 103 species in vegetation with at least 60% coverage of invasive species and 111 species in non-invasive vegetation. H. tuberosus and S. canadensis showed a significant dominance in non-native taxa. We recorded a frequent occurrence of S. nigrum and A. retroflexus in uninvaded (without invasive species) vegetation from other species. E. crus-galli, R. caesius a H. lupulus prevailed in non- invasive relevés. The results show that the difference in diversity between invasive and non-invasive

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vegetation is very high. There is a reduction of diversity and progressive crowding out of native species in the areas with a significant majority of invasive species.

ACKNOWLEDGEMENT This article was created with support of the project VEGA - > 1/0109/13 - Interaction of living organisms in anthropogenic environment.

REFERENCES Benčať, T., Pažitný, J. 2007. Prirodzené a ohrozené úseky brehových porastov horného toku Žitavy. In Ekológia a environmentalistika 2007 – Medzinárodná vedecká konferencia k 15. výročiu založenia Fakulty ekológie a environmentalistiky TU vo Zvolene a 55. výročiu vzniku Technickej univerzity vo Zvolene. Zvolen, Slovensko, 22–23 Máj. Zvolen: JANKA ČIŽMÁROVÁ – PARTNER, pp. 152–162. Dostál, J., Červenka, M. 1991. Veľký kľúč na určovanie vyšších rastlín I. 1. vyd., Bratislava: SPN. Dostál, J., Červenka, M. 1992. Veľký kľúč na určovanie vyšších rastlín II. 1. vyd., Bratislava: SPN. Gojdičová, E., Cvachová, A., Karasová, E. 2002. Zoznam nepôvodných, inváznych a expanzívnych cievnatých rastlín Slovenska.Ochrana prírody, 21: 59–79. Hejda, M., Pyšek, P. 2006. What is the impact of Impatiens glandulifera on species diversity of invaded riparian vegetation? Biological Conservation, 132(2): 143–152. Křivánek, M. 2006. Biologické invázie a možnosti ich predpovede (Predikační modely pro stanovení invazního potenciálu vyšších rostlin). Acta Pruhoniciana, 84: 3–73. Marhold, K., Hindák, F. 1998. Zoznam nižších a vyšších rastlín Slovenska(Checklist of non-vascular and vascular plants of ).1. vyd., Bratislava: Veda. Mazúr, E., Lukniš, M. 1980. Geomorfologické jednotky (1 : 500 000). In: Atlas Slovenskej socialistickej republiky. Bratislava: SAV, pp. 54–55. Melgoza, G., Nowak, R.S., Tausch, R.J. 1990. Soilwater exploitation after fire: Competition between Bromus tectorum [cheatgrass] and two native species. Oecologia 83(1): 7–13. Nentwig, W. (ed.) 2014. Nevítaní vetřelci – Invazní rostliny a živočichové v Evropě. Praha: Academia. Porubský, A. 1991. Vodné bohatstvo Slovenska. Bratislava: Veda. Pyšek, P., Prach, K., Mandák, B. 1998. Invasion of alien plants into habitats of central European landscape: an historical pattern. In Plant invasions: Ecological mechanisms and human responses. Leiden: Backhuys Publishers, pp. 23–32. Shine, C., Williams, N., Gundling, L. 2000. A Guide to Designing Legal and Institutional Frameworks on Alien Invasive Species. Germany: IUCN - The World Conservation Union. StatSoft, Inc. 2007. STATISTICA (data analysis software system), version 8.0. www.statsoft.com Stohlgren, T.J., Schell, L.D., Rimar, K.A., Otsuki, Y., Lee, M., Kalkhan, M.A., Villa, C.A. 2002. Assesing vulnerability to invasion by non-native plant species at multiple spatial scales. Environmental Management, 29(4): 566–577. Šimo, E., Zaťko, M. 2002.Typy režimu odtoku. In Atlas krajiny SR. 1. vyd., Banská Štiavnica: MŽPSR; SAŽP; ESPRIT. ter Braak, C.J.F., Šmilauer, P. 2002. CANOCO Reference Manual and CanoDraw for Windows User´s Guide – Software for Canonical Community Ordination (version 4.5). Microcomputer Power, Ithaca: NY. Tichý, L. 2002. JUICE, software for vegetation classification. In Journal of Vegetation Science 13(3): 451– 453. van der Maarel, E. (ed.) 2005. Vegetation Ecology. 1.edit., Oxford: Blackwell Publishing. Zavaleta, E. 2000. Valuing ecosystem services lost to Tamarix invasion. In Invasive species in a changing world. Washington DC: Island Press.

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