HACQUETIA 8/2 • 2009, 159-174 DOI: 10.2478/v10028-009-0011-1 MACROPHYTE VEGETATION OF ARTIFICIAL WATER RESERVOIRS IN THE KRUPINSKA PLANINA MTS., INCLUDING THE FIRST RECORD of POTAMETÜM ACUTÎFOLII FROM SLOVAKIA Richard HRIVNÂK* Abstract Research of macrophyte vegetation of the artificial water reservoirs was carried out during the vegetation season of 2008 in the Krupinskâ planina Mts. (southern part of central Slovakia). Twenty-one reservoirs were studied and twenty plant communities from the Lemnetea, Potametea and Phragmito-Magnocaricetea classes were found. Potametum acutifolii is a new aquatic community for the territory of Slovakia that was found in the reservoir near Hrušov village in intermediately deep, slightly alkaline water with a relatively low content of soluble mineral matters, a high water transparency and a silt-clay sediment on the bottom. Moisture was the main environmental gradient of the studied vegetation explained by Ellenberg's indicator values. Species richness was significantly negatively correlated with water depth. The correlation between the area of reservoirs and the number of detected plant communities was weak and non-significant. Changes of macrophyte vegetation were studied on the case of three reservoirs. Detected changes were caused mainly by human activities or water level fluctuations within the studied period. Key words: aquatic and marsh vegetation, plant community changes, ecology, DCA. Izvleček Raziskave makrofitske vegetacije umetnih vodnih smo izvedli v vegetacijski sezoni leta 2008 v hribovju Krupinska planina (južni del osrednje Slovaške). Raziskali smo enaindvajset vodnih teles in našli dvaindvajset rastlinskih združb iz razredov Lemnetea, Potametea in Phragmito-Magnocaricetea. Asociacija Potametum acutifolii je nova vodna rastlinska združba, najdena na ozemlju Slovaške. Našli smo jo v vodnem telesu blizu vasi Hrušov v srednjegloboki, rahlo alkalni vodi z razmeroma nizko vsebnostjo raztopljenih mineralnih snovi, z visoko vodno prepustnostjo in muljasto-glineno usedlino na dnu. Glavni okoljski gradient obravnavane vegetacije, kot kažejo Ellenbergove indikacijske vrednosti, je vlažnost. Število vrste je v negativni odvisnosti z globino vode. Korelacija med površino vodnega telesa in številom najdenih rastlinskih združb je bila nizka in ni bila značilna. Spremembe makrofitske vegetacije smo proučevali v treh vodnih zbiralnikih. Opažene spremembe so posledica predvsem človeških dejavnosti ali nihanja vodnega nivoja v obravnavanem obdobju. Ključne besede: vodna in močvirna vegetacija, spremembe rastlinske združbe, ekologija, DCA. 1. INTRODUCTION Anthropogenic aquatic habitats as water reservoirs are unique localities in cultural and human-exploited landscape. Their value increases when natural aquatic habitats are destroyed or strongly changed by human acitivities. In that case, they represent substitute habitats for indigenous aquatic and marsh vegetation. In the past, the information about vegetation of artificial aquatic habitats in the teritorry of Slovakia was relatively scarce (e.g. Ot'ahel'ovâ & Husak 1992). More intensive research started recently (Hrivnâk 1999, Ot'ahel'ovâ 2005, Jursa & Ot'ahel'ovâ 2005, Ot'ahel'ovâ & Ot'ahel' 2006). Until this period, research activities of botanists had been concentrated on natural aquatic habitats with stagnant water (e.g. river oxbows or natural flooded terrain depressions), which are situated in the val- * Institute of Botany, Slovak Academy of Sciences, Dubravskâ cesta 14, SK-845 23 Bratislava, Slovakia; e-mail: richard. hrivnak@savba.sk 153 HACQÜETIA 8/2 • 2009, 115-128 leys of bigger rivers such as the Danube, Morava or Latorica (e.g. Šomšak 1963, Ot'ahel'ovâ 1980, Ot'ahel'ovâ & Husâk 1982, Ot'ahel'ovâ & al. 1994). In general, research of aquatic and marsh vegetation was concentrated into areas with its optimum occurrence, i.e. mainly lowlands and uplands of southern and south-eastern parts of Slovakia. Al-titudinally higher and more northern areas have been neglected for a relatively long time. Similarly, research of artificial aquatic habitats started in the last years and data from several Carpathian basins and mountains were published (e.g. Hrivnâk 2002a, Hrivnâk & al. 2004, Hrivnâk & Kochjarovâ 2008, Ot'ahel'ovâ & al. 2008). Krupin-skâ planina Mts. is an interesting region of Slovakia where no hydrobotanical research has yet been performed (Fig. 1). I chose this area for the study of macrophyte vegetation of the artificial water reservoirs from following reasons: 1) the study area is situated on the border of two phytogeo-graphical regions, southern part in the Pannoni-cum and northern part in the Carpaticum regions (cf. Futâk 1980), which reflects mainly different climatic characteristics; 2) there are enough appropriate habitats (artificial water reservoirs) for the study to be relatively representative; 3) no complex research of macrophyte vegetation has been done in the study area; 4) there is only limited knowledge on plant communities of artificial water reservoirs from the past, but some of the information available is suitable for a comparison with the results presented in this paper (e.g. Hrivnâk 1999; Hrivnâk 2002b, 2004). Therefore, the main aim of this work is a complex phytosoci-ological and ecological evaluation of macrophyte vegetation of the artificial water reservoirs in the Krupinskâ planina Mts., including evaluation within a broader regional context as well as comparison of changes of selected water reservoirs. 2. STUDY AREA Macrophyte vegetation was studied in the Kru-pinskâ planina Mts (Fig. 1). The mountain is situated in the southern part of central Slovakia with altitudinal range from the lowland to the submountain level. It is a typical volcanic mountain range formed mainly of andesites. From the hydro-logical point of view, the study area belongs to the Ipel' river catchment area with the following larger rivers and streams: Krupinica, Litava, Vrbovok, Plachtinsky potok and Krriš. A substantial part of Figure 1: Study sites. Slika 1: Lokacije preučevanih zbiralnikov. the area belongs to the warm or moderately warm region with a mean annual air temperature and a precipitation total of 6 to 7 °C and 600 to 700 mm, respectively (Miklos 2002). Twenty-one artificial water reservoirs with various areas, recent uses and statuses were studied and their characteristics are briefly presented in Table 1. 3. METHODS Phytosociological relevés were taken according to the Zürich-Montpellier approach. Only stands with at least the minimum areas recommended for this type of vegetation were recorded (Chytry & Otypkovâ 2003). Macrophyte vegetation data were collected in 2008. Fifty-three phytosocio-logical relevés were collected. All the relevés were stored using the TURBOVEG database (Hennekens & Schaminée 2001) and then exported and processed by the JUICE software (Tichy 2002). Further, they were analysed by TWINSPAN (Hill 1979) with application of the dominance principle. CANOCO 4.5 for Windows package (ter Braak & Šmilauer 2002) was used for a detrended correspodence analysis (DCA); species percentage data with logarithmic transformation were used and rare species were downweighted. For the ecological interpretation of major gradients 159 Richard Hrivnäk: Macrophyte vegetation of artificial water reservoirs in the Krupinska planina Mts of the studied wetland vegetation, average non-weighted Ellenberg's indicator values of vascular plant species (Ellenberg & al. 1992) were plotted onto a DCA ordination diagram as supplementary variables. The associations between some selected environmental and species variables were expressed by Spearmann correlation coeficients using the STATISTICA software (StatSoft 2001). Water reaction and conductivity were measured in selected water reservoirs by pH-meter/con-ductometer WTW pH/Cond 340i. The position and area of the studied sites was obtained using GPS eTrex Summit fy Garmin and Gis (Arcview programme) from digital orthophotomaps with a resolution of 1 m to pixel. Data from older papers (Hrivnâk 1999; Hrivnâk 2002b, 2004) were used for a comparison of diversity and plant communities changes within selected water reservoirs. The nomenclature of plants follows Marhold and Hindâk (1998). The names of vegetation units are presented with author's name and year of description. 4. RESULTS AND DISCUSSION Checklist of vegetation units Lemnetea O. de Bolos et Masclans 1955 Lemnetalia minoris R. Tx. 1955 Lemnion minoris R. Tx. 1955 Lemno minoris-Spirodeletum polyrhizae Koch 1954 em. Th. Müller et Görs 1960 (Tab. 2, rels 1-3) Hydrocharitetalia Rübel 1933 Hydrocharition morsus-ranae Rübel 1933 em. Westhoff et Den Held 1969 Ceratophylletum demersi Hild 1956 (Tab. 2, rel. 4) Potametea Klika in Klika et Novâk 1941 Potametalia Koch 1926 Nymphaeion albae Oberd. 1957 Potametum natantis von Soo 1927 (Tab. 2, rels 7-10) Polygonetum amphibii von Soo 1927 (Tab. 2, rels 5-6) Potametum nodosis Passarge 1964 (Tab. 2, rel. 13) Potamion pusilli Hejny 1978 Potametum pectinati Carstensen 1955 (Tab. 2, rel. 15) Potametum acutifolii Segal 1961 (Tab. 2, rels 11-12) Potametum trichoidis Tüxen 1974 (Tab. 2, rel. 14) Phragmito-Magnocaricetea Klika in Klika et Novâk 1941 Phragmitetalia Koch 1926 Phragmition australis Koch 1926 Equisetetumfluviatilis Steffen 1931 (Tab. 3, rels 1-2) Glycerietum aquaticae Hueck 1931 (Tab. 3, rels 3-4) Phragmitetum vulgaris von Soo 1927 (Tab. 3, rel. 5) Scirpetum lacustris Chouard 1924 (Tab. 3, rels 11-12) Sparganietum erecti Roll 1938 (Tab. 3, rels 6-10) Typhetum angustifoliae Pignatti 1953 (Tab. 3, rels 13-18) Typhetum latifoliae Lang 1973 (Tab. 3, rels 19-27) Magnocaricion elatae Koch 1926 Caricenion gracilis (Neuhäusl 1959) Oberd. et al. 1967 Caricetum vesicariae Chouard 1924 (Tab. 3, rels 28-30) Phalaridetum arundinaceae Libbert 1931 (Tab. 3, rel. 31) Nasturtio-Glycerietalia Pignatti 1953 Sparganio-Glycerion Br.-Bl. et Sissing in Boer 1942 Glycerietum Jluitantis Eggler 1933 (Tab. 3, rels 32-34) Leersietum oryzoidis Eggler 1933 (Tab. 3, rels 35-36) Oenanthetalia aquaticae Hejny in Kopecky et Hejny 1965 Oenanthion aquaticae Hejny ex Neuhäusl 1959 Eleocharitetum palustris Ubrizsy 1948 (Tab. 3, rels 37-38) 4.1 Phytosociological and ecological characteristics of plant communities Duck-weed vegetation (Lemnetea) was rare in the studied area (Tab. 2). Two associations were found, Lemno minoris-Spirodeletum polyrhizae and Ceratophylletum demersi, the former being more frequent. Stands of Lemno minoris-Spirodeletum po-lyrhizae grew in small, shallow, eutrophic and silt- 161 HACQÜETIA 8/2 • 2009, 115-128 Figure 2: Plašt'ovce water reservoir. Stands of Ceratophylletum demersi, Leersietum oryzoidis and Typhetum latifoliae in tributary part of reservoir. Slika 2: Vodni zbiralnik Plašt'ovce. Sestoji asociacij Ceratophylletum demersi, Leersietum oryzoidis in Typhetum latifoliae v delu zbiralnika s pritoki. ed reservoirs near human settlements. A similar characteristic is generally typical for this community in various European countries (Schratt 1993, Ot'ahel'ovâ 1995a, Coldea 1997), although its ecological amplitude is markedly broader (Tomasze-wicz 1979, Sumberovâ 2007). In Slovakia, the occurrence of this community is known mainly from lowlands and basins in the southern part of the country (Otahel'ovâ 1980, 1995a; Ot'ahel'ovâ & al. 1985, 1994; Zlinskâ & Kubalovâ 2001, Hrivnâk 2002c). Ceratophyllum demersum overgrew the water reservoir PMšt'ovce (Fig. 2), where the mentioned dominant species created large, dense, submerged and species-poor stands. Association Ceratophylletum demersi frequently occurs in Slovakia (Ot'ahel'ovâ 1995a). Hrivnâk (2002c) reported about the occurrence of Lemnetum minoris in Figure 3: Stands of the Potametum natantis association in the water reservoir near Hrušovo village. Slika 3: Sestoji asociacije Potametum natantis v vodnem zbiralniku v bližini vasi Hrušovo. 162 Richard Hrivnäk: Macrophyte vegetation of artificial water reservoirs in the Krupinska planina Mts Figure 4: Stands of Potametum nodosi and Typhetum angus-tifoliae associations in the littoral of the Kosihovska Bukovina water reservoir. Slika 4: Sestoji asociacij Potametum nodosi in Typhetum an-gustifoliae v obrežnem pasu vodnega zbiralnika Kosihovska Bukovina. Figure 5: Stands of Polygonetum amphibii in the Velky Šiaš water reservoir. Slika 5: Sestoji asociacije Polygonetum amphibii v vodnem rezervoarju Velky Šiaš. a water reservoir near the Hrušov village, which was not confirmed within recent research. Regarding the diversity of the detected plant communities and number of relevés, the communities of the Potametea class were relatively better represented (Tab. 2). Stands with the dominance of species of the genus Potamogeton were mainly found. Among the broad-leaved species of this genus, P. natans was more frequent than P. nodo-sus. Potametum natantis (Fig. 3) created closed or moderately open stands in deeper waters. Dominant species of this community (P. natans) often grew also in other aquatic and marsh plant communities. On the territory of Slovakia, Potametum natantis is relatively frequent and occurs from the lowland up to the montane level (cf. Ot'ahel'ovâ 1995b; Hrivnâk 2002b; Hrivnâk & al. 2004, 2009). Potametum nodosi grew in the littoral of the water reservoir Kosihovskâ Bukovina (Fig. 4). Data about this community from Slovakia indicated its occurrence mainly in running waters (Otahelovâ 1995b). The community is rare in stagnant waters (e.g. Otahelovâ 2005), although the dominant species P. nodosus has an optimum of occurrence from stagnant to moderately flowing waters (Willby & al. 2000). The last detected community from the Nymphaeion albae alliance is Polygonetum amphibii (Fig. 5). The association formed open and smaller stands in shallow to moderately deep waters. Among vegetation of the linear-leaved submerged species of the genus Potamogeton, Potametum pecti-nati, P. trichoidis and P. acutfolii associations were found, but their occurrence was relatively rare. Potametum pectinati formed larger stands in the water reservoir near Čekovce village, Potametum trichoidis occurred fragmentarily in the water reservoir Kozi Vrbovok. The former association occurs relatively often in Slovakia (cf. Otahelovâ 1995b). On the other hand, reports about the latter association are very rare (e.g. Hâberovâ & Karasovâ 163 HACQÜETIA 8/2 • 2009, 115-128 1991, Hrivnâk 2002b, Kubalovâ 2009). Potametum acutifolii is a new community for the territory of Slovakia (cf. Ot'ahel'ovâ 1995b, JaroHmek & al. 2008). Stands of this community were found in the water reservoir near Hrušov village where it formed mosaic stands with Potametum natantis. In the Potametum natantis stand, Potamogeton acuti-folius was found in the past (cf. Hrivnâk 2002b). The dominant species P. acutifolius occurred in almost all plant communities within the reservoir (cf. Tab. 2 a 3). In addition to the mentioned dominant species, floating hydrophytes (Potamogeton natans and Lemna minor) in deeper water and helophytes in shallower water were detected in the stands of Potametum acutifolii (Tab. 2, rel. 11). The water was 70-100 cm deep, slightly alkaline with a relatively low content of soluble mineral matters (cf. Tab. 1) and with a high water transparency (95 cm measured by Secchi disk). The bottom was formed of fine material (silt-clay sediment). Low concentrations of ammonia (0.126 mg/l) and nitrites (0.154 mg/l), and slightly higher values of nitrates (2.189mg/l) and phosphates (1.328 mg/l) in water were detected. In general, this community grows in small ponds, in shallow and eutrophic, neutral or alkaline water with various sediments on the bottom (Tomaszewicz 1979; Rydlo 2005, 2006; Nowak & al. 2007). Stands are species-poor and in addition to dominant species P. acutifolius, various aquatic plants grow in stands of this community (Tomaszewicz 1979, Nowak & al. 2007, Sumberovâ & Hrivnâk 2010). These facts are similar to those identified in the Krupinskâ planina Mts. Among Central European countries, the community rarely occurs in Poland (Matusz-kiewicz 2001, Nowak & al. 2007), the Czech Republic (Sumberovâ & Hrivnâk 2010) and Germany (Pott 1992). It is interesting that in the Czech Republic Potamogeton acutifolius is quite abundant (Kaplan 2001), but stands with its dominance are rare (Sumberovâ & Hrivnâk 2010). The most diverse groups of the studied vegetation are the marsh communities, where 12 associations were detected. More than a half of them belong to typical littoral marsh communities of the Phragmition communis alliance. The most frequent are Typhetum latifoliae, T. angustifoliae and Spargani-etum erecti. All are frequent not only in the studied area, but within the whole territory of Slovakia (Ot'ahel'ovâ & al. 2001). Species composition reflects the actual ecophase (sensu Hejny 1960): in addition to dominant species, true aquatic species (Lemna minor, Potamogeton spec. div.) grow in Figure 6: Water reservoir near Duchenec village with large stands of Equisetum limosi and Typhetum latifoliae in the littoral after strong rainfall. Slika 6: Vodni zbiralnik pri vasi Duchenec z obsežnimi sestoji asociacij Equisetum limosi in Typhetum latifoliae v obrežnem pasu po obilnem deževju. the littoral ecophase, the number of typical marsh species increases with a decrease of water level and species of eutrophic sediments such as Bidens spec. div., Persicaria hydropiper or Leersia oryzoides grow in the limose ecophase. Less frequent are the following 4 communities: Glycerietum aquaticae, Phrag-mitetum vulgaris, Scirpetum lacustris and Equisetetum limosi. Equisetetum limosi is interesting for its occurrence in water reservoirs near Duchenec (Fig. 6) and Riečky villages. This association has a boreal-subatlantic distribution (Balâtovâ-Tu^kovâ & al. 1993) and in Slovakia it occurs from the upland to the montane levels and very rarely also in lowlands (cf. Ot'ahel'ovâ & al. 2001). Accessible data about this association in Slovakia are relatively rare and data from phytogeographical region Ipel'sko-rimavskâ brâzda are absent at present. The Mag-nocaricion elatae alliance is represented only by two associations, Caricetum vesicariae and Phalar-idetum arundinaceae. Both of them are rare in the study area and the occurrence of the former one is fragmentary. Glycerietumfuitantis and Leersietum oryzoidis grew on silted and deep sediment within inflow parts of reservoirs. The water was shallow or sometimes only the sediment was waterlogged. Similar ecological characteristics were typical also for Eleocharitetum palustris, stands of which were found in the water reservoir of Kosihovskâ Bukovina from shallow to moderately deep water. The community survives well within disturbed habitats, too. Great water level fluctuation is typical 164 Richard Hrivnäk: Macrophyte vegetation of artificial water reservoirs in the Krupinska planina Mts for all three communities. Similar characteristics were reported from several European countries (e.g. Balatova-Tulačkova & al. 1993, Coldea 1997, Otahel'ova & al. 2001, Stančič 2007). Based on the Ellenbergs indicator values, I detected that the main environmental gradient is clearly the factor "Moisture" (Fig. 7). This factor correlates most closely with the first DCA axes Figure 7: Ordination diagram of both species and sample data with supplementary environmental variables (Ellenberg indicator values) and number of species. Full circles - aquatic plant communities of the Lemnetea and Potametea classes, shaded squares - reed vegetation of the Phragmition communis alliance, empty rectangles - marsh vegetation of the Oenanthion aquaticae and Glycerio-Sparganion alliances, crosses - tall-sedges vegetation of the Magnocaricion alliance. The first two axes explain 15.3 and 32.0 % of species variability and species-environment relation, respectively. Weighted correlations between first two axes and environmental variables: Light: 0.2907 and -0.1900, Temperature: -0.3766 and -0.1107, Continentality: 0.0184 and -0.0585, Moisture: -0.7794 and -0.3385, Soil reaction: -0.0721 and -0.2217, Nutrients: 0.3599 and -0.0848. Slika 7: Ordinacijski diagram vrst in popisov z dodatnimi okoljskimi spremenljivkami (Ellenbergove indikacijske vrednosti) in število vrst. Polni krogi - vodne rastlinske združbe razredov Lemnetea in Potametea, zasenčeni kvadrati - trstje, ki ga uvrščamo v zvezo Phragmition communis, prazni pravokotniki - močvirna vegetacija zvez Oenanthion aquaticae in Glycerio-Sparganion, križi - visoko šašje, ki ga uvrščamo v zvezo Magnocaricion. Prvi dve osi pojasnita 15,3 in 32,0 % vrstne variabilnosti oziroma odnosa rastlinske vrste - okolje. Tehtana korelacija med prvima dvema osema in okoljskimi spremen-ljivakami: svetloba: 0,2907 in -0,1900, toplota: -0,3766 in -0,1107, kontinentalnost: 0,0184 in -0,0585, vlažnost: -0,7794 in -0,3385, reakcija tal: -0,0721 in -0,2217, hranila: 0,3599 in -0,0848. Abbreviations of species (Okrajšave vrst): Alislan - Alisma lanceolatum, Alispla - Alisma plantago-aquatica, Alopaeq - Alopecurus aequalis, Ranutri - Batrachium trichophyllum, Bidefro - Bidens frondosa, Bidetri - Bidens tripartitus, Calysep - Calystegia sepium, Careces - Carex cespitosa, Careela - Carex elata, Careves - Carex vesicaria, Ceradem - Ceratophyllum demerum, Eleopal - Eleocharis palustris, Epilhir - Epilobium hirsutum, Equiflu - Equisetum fluviatile, Equipal - Equisetum palustre, Filiulm - Filipendula ulmaria, Galipal - Galium palustre, Glycflu - Glyceria fluitans, Glycmax - Glyceria maxima, Humulup - Humulus lupulus, Irispse - Iris pseudacorus, Junceff - Juncus effusus, Leerory - Leersia oryzoides, Lemnmin - Lemna minor, Lycoeur - Lycopus europaeus, Lysyvul - Lysimachia vulgaris, Lythsal - Lythrum salicaria, Mentarv - Mentha arvenis, Mentaqu - Mentha aquatica, Myospal - Myosotis scor-pioides agg., Persamp - Persicaria amphibia, Pershyd - Persicaria hydropiper, Perslap - Persicaria lapathifolia, Phalaru - Phalaroides arundinacea, Oenaaqu - Phellandrium aquaticum, Phraaus - Phragmites australis, Poa tri - Poa trivialis, Potaacu - Potamogeton acutifolius, Potacri - Potamogeton crispus, Potanat - Potamogeton natans, Potanod - Potamogeton nodosus, Potapec - Potamogeton pectinatus, Potatri - Potamogeton trichoides, Riccflu - Riccia fluitans, Sangoff - Sanguisorba officinalis, Salicin - Salix cinerea, Salifra - Salix fragilis, Scholac - Schoenoplectus lacustris, Scirsyl - Scirpus sylvaticus, Scutgal - Scutellaria galericulata, Soladul - Solanum dulcamara, Sparere - Sparganium erectum, Spirpol - Spirodella polyrhiza, Stacpal - Stachys palustris, Typhang - Typha angustifolia, Typhlat - Typha latifolia, Urtidio - Urtica dioica. 165 HACQÜETIA 8/2 • 2009, 115-128 Figure 8: Water reservoir near Hrušov village with the most various macrophyte vegetation and with occurrence of the Potametum acutiformis association. Slika 8: Vodni zbiralnik pri vasi Hrušov z najbolj raznoliko makrofitsko vegetacijo in spojavljanjem sestojev asociacije Potametum acutiformis. (-0.78). Along the moisture gradient, individual communities were arranged more or less according to the natural hydrosere of habitats with stagnant water. From the left to the right side of the DCA ordination graph, aquatic communities of the Potametea class are the first displayed, followed by pleustophyte vegetation of the Lemnetea class and littoral communities of the Phragmition communis alliance and finished by marsh vegetation of shallow waters of the upper littoral of the Magnocaricion elatae, Sparganio-Glycerion and Oe-nanthion aquaticae alliances. True aquatic plants, such as species of the Potamogeton genera, Persi-caria amphibia f. natans or some helophytes such as Phragmites australis, Schoenoplectus lacustris or Typha angustifolia (left side of Fig. 7) are typical for permanent and deeper waters. Wet meadow species (e.g. Poa trivialis, Myosotis scorpioides agg. or Juncus effusus), some nitrophilous, liana species or species of exposed substrates (e.g. Urtica dioica, Calystegia sepium and Alopecurus aequalis) are displayed on the other side of the moisture gradient (the right side of Fig. 7). Species richness increases with decreasing water depth. The correlation between the number of species and water depth in individual relevés is statistically significant (P < 0.001), although the correlation coefficient is relatively low (Spearman's r = -0.506). The same is indicated by Fig. 7, where a negative correlation between moisture and the number of species (r = -0.555, P < 0.001) is obvious. It is caused by the presence of true aquatic plants as well as marsh and wet meadow species in shallower waters, representing appropriate conditions for all species groups. Interaction between the size of individual reservoirs and number of detected plant communities is weak and non-significant (r = 0.436, P = 0.1). Reservoirs with relatively small size can be rich in macrophyte vegetation (Hrušov; Fig. 8), in contrast to large reservoirs (Kozi Vrbovok; Tab. 1). Diversity of plant communities is probably influenced by the heterogeneity of environmental conditions, mainly in the littoral of reservoirs (e.g. type of substrate, reservoir profile, morphometrical characteristics). 166 Richard Hrivnäk: Macrophyte vegetation of artificial water reservoirs in the Krupinska planina Mts 4.2 Diversity of vegetation in relation to other Slovak regions Undoubtedly, Krupinskä planina Mts. belongs to the areas with varying macrophyte vegetation of artificial water reservoirs. In general, the plant community diversity of reservoirs in the Pannon-icum region is higher than within the Carpati-cum. There are more suitable climatic conditions for development of macrophyte vegetation in the Pannonicum. For example, the following mean numbers of plant communities per artificial water reservoir were detected in individual Slovak regions: Pannonicum: Cerovä vrchovina Mts -almost 7 communities for reservoir (4 reservoirs were studied; Hrivnäk & Csiky 2009), L^enskä kotlina basin - more than 3 (10 reservoirs; Hrivnäk 1999), Ipel'skä kotlina basin - more than 6 (4 reservoirs; Ot'ahel'ovä & al. 1998, Hrivnäk 1999), Borskä nižina lowland - almost 3 (10 reservoirs; Ot'ahel'ovä 2005); Carpaticum: Zvolenskä kotlina basin - more than 2 (5 reservoirs; Hrivnäk 2002a), Nizke Tatry Mts - almost 2 (14 reservoirs; Hrivnäk et al. 2009), Hornonitrianska kotlina basin - almost 3 (13 reservoirs; Dubravkovä & al. 2009), Vel'kä Fatra Mts and Turčianska kotlina basin - almost 2 (11 reservoirs; Hrivnäk & Ko-chjarovä 2008). In the Krupinskä planina Mts, more than 3 plant communities per reservoir were detected in 15 water reservoirs. The intermediate position of vegetation diversity in this area fully corresponds with the phytogeographical position of the studied region, which includes both Pannonicum and Carpaticum. 4.3 Comparison of macrophyte community changes Three artificial water reservoirs were chosen for a comparison of changes of macrophyte vegetation: Drienovo (in village; No. 4 in Table 1), Hrušov (6) and Cerovo, Vel'ky Šiaš (13). For these reservoirs, relatively the most detailed information about the studied vegetation types was available (Table 4). The most important changes were detected in the case of the first-mentioned reservoir (Drienovo). Three plant communities were found at this location in the past, but no community was detected during the recent research; only their fragments affected by strong human impact grew in the littoral of the reservoir (Fig. 9). The locality is situ- Figure 9: Water reservoirs in Drienovo village. Slika 9: Vodni rezervoar v vasi Drienovo. 167 HACQÜETIA 8/2 • 2009, 115-128 ated on the margin of a village and the reservoir is used for many human activities. Vegetation in the littoral and on the banks is frequently mown during the vegetation period. All these activities inhibit development of littoral vegetation. Heavily eutrophic water is often overgrown by cyano-phytes, which inhibits the development of aquatic vegetation as well. Within the second reservoir under study (Hrušov), no negative changes were determined. Only Eleocharitetum palustris was missing at present (mentioned in the 1990's; cf. Hrivnâk 1999), but it may re-appear if the water level decreases. Individuals of Eleocharis palustris were frequent in the littoral of the reservoir, but they did not form larger stands. On the other hand, 6 new communities were found in the reservoir, which were not mentioned in the past. At the last locality (Vel'ky Šiaš), changes result from the difference in water level during studies in the past and in 2008. The occurrence of Typhetum an-gustifoliae and Potametum natantis was detected in the past as well as during the recent research, always during the period of more or less stable higher water level (cf. Hrivnâk 2002b, 2004). The next two communities, Polygonetum amphibii and Lemnetum minoris were found in only one surveyed season. Both communities have a seasonal character, very often they grow fragmentar-ily and in dependence on various environmental conditions (Ot'ahel'ovâ 1995a, b). Stands of Oe-nantho aquaticae-Rorippetum amphibiae and Jun-cus bufonius comm. grew on the exposed bottom of the reservoir (cf. Hrivnâk 1999). Water level increasing above the usual value was observed during recent research in 2008. 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Status Recent use Pc 1 Plašt'ovce W from village 18° 57' 11.0" 48° 09' 42.5" 175 2.635 9.5 231 water-filled F, Fe, I, R 3 2 Devičie S margin of village 19° 01' 31.2" 48° 18' 13.9" 251 drained 0 1 3 Drienovo Antalov Laz 19° 02'25.6" 48° 13' 11.2" 339 drained W 2 4 Drienovo in village 19° 03'42.8" 48° 13' 57.0" 372 0.627 water-filled R 0 5 Cabradsky Vrbovok SW from village 19° 04' 14.0" 48° 15' 11.3" 309 drained 0 0 6 Hrušov N from village 19° 05'03.2" 48° 10' 45.3" 400 0.389 7.6 148 water-filled F, Fe, I, R 9 7 Homy Badin Lazy 2 19° 05'20.1" 48° 17' 22.7" 340 0.050 water-filled W 1 8 Homy Badin Lazy 1 19° 05'21.1" 48° 17'25.1" 340 0.041 7.5 197 water-filled W 2 9 Kozi Vrbovok SW from village 19° 05' 55.9" 48° 17' 11.7" 325 14.254 8.1 233 water-filled F, Fe, I 2 10 Čekovce S from village 19° 07'07.2" 48° 20' 48.5" 389 1.358 water-filled F, Fe, I 3 11 Cerovo Pod blatami 19° 08' 16.2" 48° 15' 12.5" 391 drained rec 0 12 Cerovo Pri badluckej ceste 19° 08'45.7" 48° 15' 51.5" 414 0.876 water-filled Ff, I 3 13 Cerovo Vefky Šiaš 19° 09'02.7" 48° 16' 07.3" 420 1.589 water-filled Ff, I 4 14 Cerovo S from village 19° 09'05.4" 48° 14' 45.5" 415 drained W 1 15 Pliešovce Bzovskâ Lehôtka 19° 09'07.1" 48° 24' 35.4" 421 6.295 9.1 150 water-filled F, Fe, I, R 4 16 Cerovo in village 19° 09'27.0" 48° 15'27.5" 448 0.177 water-filled I 0 17 Duchenec NNW from village 19° 11'29.3" 48° 15' 33.2" 492 0.188 8.2 water-filled Fe, I 3 18 Opavské Lazy Kosihovskâ Bukovina 19° 11'48.4" 48° 13'01.7" 486 2.630 9.7 121 water-filled F, Fe, I 6 19 Modiy Kamen, Riecky Kamenny vrch 19° 17' 24.3" 48° 18'01.6" 442 2.995 water-filled F, Fe, I 5 20 VclLy Lom N from village 19° 22' 11.2" 48° 20' 38.9" 437 0.135 water-filled W 3 21 VclLy Lom S margin of village 19° 22'26.5" 48° 19' 55.5" 402 drained 0 1 Legend: N - number; Long. - Longitude (central part), Lat. - Latitude (central part), Alt. - Altitude, pH - Water pH, Cond. - Water conductivity (|iS/cm; 25 °C); Recent use: F - fishing, Fc - flood control, I - irrigation of farm land, R - recreation, rec - reconstruction, W - without any utilization, 0 - long-term drained; Pc - number of plant communities. Legenda: N - število; Long. - zemljepisna dolžina (osrednji del), Lat. - zemljepisna širina (osrednji del), Alt. - nadmorska višina, pH - pH vode, Cond. - prevodnost vode (|iS/cm; 25 °C); sedanja raba: F - ribolov, Fc - uravnavanje poplav, I - namakanje kmetijskih površin, R - rekreacija, rec - obnova, W - brez posebnega namena, 0 - dolgotrajno osušeno; Pc - število rastlinskih združb. HACQÜETIA 8/2 • 2009, 115-128 Table 2: Aquatic vegetation of the studied water reservoirs. Tabela 2: Vodna vegetacija preučevanih vodnih zbiralnikov. * Relevé number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Water reservoir 20 8 7 1 13 10 20 17 13 6 6 6 18 9 10 Cover (%) 98 100 95 100 55 90 80 50 95 95 100 100 75 95 80 Relevé area (m2) 20 16 16 16 6 9 20 16 12 16 14 14 12 12 16 Depth of water (cm) 40 10 10 100 55 90 100 150 80 105 80 100 80 45 115 Sediment type F F F F F F F F F S/F Dominant species of associations Le Lemna minor Le Spirodela polyrhiza Le Ceratophyllum demersum Po Persicaria amphibia f. natans Po Potamogeton natans Po Potamogeton acutifolius Po Potamogeton nodosus Po Potamogeton trichoides Po Potamogeton pectinatus Other species Pm Glyceria fluitans Pm Phellandrium aquaticum Pm Alismaplantago-aquatica Pm Eleocharis palustris 5 + 4 + 4 3 + a 1 1 + + + m a a 5 4 5 4 5 1 + r + r r + Legend: * Le - Lemnetea, Po - Potametea, Pm - Phragmito-Magnocaricetea; full headers with higher accuracy location of individual relevés are presented in the Slovak national phytosociological database (http://ibot.sav.sk/cdf/index.html). Sediment type: F - anorganic or organic fine sediment, S - stone or artificial block sediment. Species only in one relevé (Vrste samo v enem popisu): Alisma lanceolatum (7: +), Batrachium trichophyllum (14: r), Carex vesicaria (11: 1), Equisetum fluviatile (8: 1), Lycopus europaeus (6: +), Salix fragilis (1: r), Sparganium erectum (9: +), Typha latifolia (6: +). Legenda: * Le - Lemnetea, Po - Potametea, Pm - Phragmito-Magnocaricetea; celotna glava popisov z večjo natančnostjo lokacije je shranjena v Slovaški nacionalni fitocenološki podatkovni bazi (http://ibot.sav.sk/cdf/index.html). Tip sedimenta: F - anorganski ali organski fini sediment, S - kamenje ali umetni kamniti sediment. Table 3: ^ Full headers with higher accuracy location of individual relevés are presented in the Slovak national phytosociological database (http://ibot.sav.sk/cdf/index.html). Celotna glava popisov z večjo natančnostjo lokacije je shranjena v Slovaški nacionalni fitocenološki podatkovni bazi (http:// ibot.sav.sk/cdf/index.html). 172 Richard Hrivnäk: Macrophyte vegetation of artificial water reservoirs in the Krupinska planina Mts Table 3: Marsh vegetation of the studied water reservoirs. Table 3: Močvirna vegetacija preučevanih vodnih zbiralnikov. Relevé number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 Water reservoir 19 17 6 15 6 18 12 10 6 3 13 6 18 13 12 9 6 15 21 19 18 17 6 14 1 7 15 19 6 15 19 19 18 3 1 2 20 18 Cover (%) 100 80 100 100 100 70 90 90 80 90 75 80 85 80 90 90 95 80 80 95 85 80 90 90 95 100 95 95 85 100 95 70 60 100 100 100 90 80 Relevé area (m2) 20 16 16 16 15 16 10 16 16 15 11 12 18 16 16 16 16 15 20 13 15 16 16 16 16 16 16 15 16 12 20 10 15 16 15 16 20 8 Depth of water (cm) 40 105 80 12 90 75 40 45 80 1 40 70 100 80 90 105 95 70 1 25 5 80 25 0 55 10 30 0 80 3 3 30 5 2 1 1 0 90 Sediment type F F F F F F F F F S/F S F S/F F F F F F F F F F F F F F F F F F F F + i Dominant species of associations Equisetumfluviatile 5 5.................+ .3........+ a . Glyceria maxima . . 54.............+........1.. + ... Phragmites australis .... 4............................ Sparganium erectum ..... 45545 .....................+1 Schoenoplectus lacustris ..........4 4..................... Typha angustifolia ..........r1 545445 ............... Typha latifolia ................ Carex vesicaria ................ Phalaris arundinacea . . . . . . . . . . . . . . . . Glyceria fluitans .....a + . . 1...... Leersia oryzoides . . . . . . . r . . . . . . . . Eleocharis palustris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aquatic plants (Lemnetea and Potametea classes) Lemna minor + . a . a + 3 + 1. +1. + + 31. .41.3.3 a 3. a Potamogeton natans ....5.. .3. 11. + ..3.....+............... Potamogeton acutifolius . . 1 . 1 . . . . . . + . . . . 1 . . . . . . . . . . . + . . . . . . . . . Spirodela polyrhiza . . . . . . . . . . . . . . . 1 . . . . . . . . . a . . . . . . . . . . . . Potamogeton nodosus . . . . . . . . . . . . + . . . . . . . . . . . . . . . . . . . . . . . . 1 Phragmito-Magnocaricetea Lythrum salicaria + . . 1 . . . . . . . . . . . . . . . . . . . . . . + 1 + 1 . 1 r . . a r . Alisma plantago-aquatica . . . . . . r . . . . . + . . . . . . + . . r . . . . . . . . + . r . r + + Lycopus europaeus . . . . . . . . . . . . . . . . . . . + . . . + . . . . . . a + . . 1 r . + Oenanthe aquatica . . + . . . + . + . . . . . . . . . . . . . 1 . . . . . + . . . . . . . . . Iris pseudacorus + . . . . . . . . . 1 . . . . . . . . . . . . . . . . + . . . + . . . . . . 4 4 4 4 5 5 4 4 5 + . . . . ......... 545 ........ . + .. +.......5 .... a .. . . . .+ b .1..... 345 . . .+ . a..............55 .1 .............+ .... 54 1 + . 1 . . + Galium palustre Lysimachia vulgaris Epilobium hirsutum Mentha aquatica Bidentetea tripartiti Bidens frondosa Bidens tripartitus Persicaria hydropiper Molinio-Arrhenatheretea Scirpus sylvaticus Filipendula ulmaria Sanguisorba officinalis Other species Juncus effusus Poa trivialis Persicaria amphibia Solanum dulcamara Urtica dioica 1 + . . + + . . + ... 1 a . + 1 + . . + . . . . + . . +. ++ 1+ + + + + ++ + + + + a + + + + + a + Species in one relevé only (Vrste samo v enem popisu): Alopecurus aequalis (34: a), Batrachium trichophyllum (21: 1), Calystegia sepium (36: +), Carex cespitosa (30: +), Carex elata (29: 1), Ceratophyllum demersum (25: 3), Equisetum palustre (19: a), Humulus lupulus (18: +), Mentha arvensis (38: +), Myosotis scorpioides agg. (31: +), Persicaria lapathifolia (34: +), Potamogeton crispus (21: +), Riccia fluitans (27: b), Salix cinerea (28: +), Salix fragilis (37: r), Scutellaria galericulata (31: +), Stachys palustris (1: r). 173 HACQÜETIA 8/2 • 2009, 115-128 Table 4: Comparison of plant communities changes within the three selected artificial water reservoirs. Table 4: Primerjava spremembe rastlinskih združb v treh izbranih umetnih vodnih zbiralnikih. Number of locality/plant community Name of locality Published paper 4 Drienovo 6 Hrušov 13 Cerovo    Acoretum calami Caricetum vesicariae Eleocharitetum palustris Glycerietum aquaticae Juncus bufonius comm. Lemnetum minoris Oenantho aquaticae-Rorippetum amphibiae Phragmitetum vulgaris Polygonetum amphibii Potametum acutifolii Potametum natantis Scirpetum lacustris Sparganietum erecti Typhetum angustifoliae Typhetum latifoliae *Earlier papers - Hrivnâk (1999; 2002a, b; 2004), **this paper. *Starejše objave - Hrivnâk (1999; 2002a, b; 2004), ** v tem delu. * ** 174