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MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary

1 Slovenia

The "Multifunctional Integrated Study Danube, Corridor and Catchment" (MIDCC)

Partner Report

Macrophytes of the Rivers Stržen, Obrh, Rak and Ljubljanica

Alenka Gaberščik Mateja Germ Nina Kržič Olga Urbanc-Berčič

National Institute of Biology & Department of Biology, Biotechnical faculty, University of Ljubljana Večna pot 111, 1000 Ljubljana, Slovenia

Ljubljana, 15th March 2005

1.1 Introduction

1.1.1 Short general description In our study we surveyed four branches of the same river called the River Ljubljanica. It is characterized as a unique river of karstic character and no more than seven names. Special environmental circumstances are basic for the phenomenon of multiple appearing and disappearing of the river and to gain the designation, a river of seven names. The origin of the river defines two branches, each collecting waters from different mountainous areas. The reason for such variety is geological background. The geology of wider area indicates a stirred up history that is still recognized in recent earthquake activity. Trbuhovica is the name of the very source. It is a short stream, quickly disappearing underground among and through the limestone rocks. Waters come up again in the Loška dolina valley under the name Obrh. The river flows underground and after 1 km it appears again. Shortly it enters the Cerkniško polje under the third name Stržen. There the water leaked out through sink holes and the rest of it leaves the surface in two caves. It came out for only two kilometers as the Rak stream, disappearing again in a cave. From the west there comes the second branch of the Ljubljanica River, the Pivka stream. Underground in a cave Planinska jama two rivers from both branches come together and appear as the Unica stream. After some kilometers it leaves the surface. The scattered waters gather for the last time at the town Vrhnika coming on a surface in two sources. Finally the river gets the name Ljubljanica and becomes the main stream of the bogs of Ljubljansko barje. After flowing through the city of Ljubljana it joins the River Sava and the River Kamniška Bistrica at the confluence of the three rivers (ENCIKLOPEDIJA SLOVENIJE 1992).

Photo 1.1.1 A densely overgrown dry stream of Mali Obrh.

Photo 1.1.2 The Veliki Obrh stream in the top of the season.

The upper parts of the River Ljubljanica are formed by three streams, the Obrh, Stržen, and Rak stream. They flow subsequently through the karst poljes in SW Slovenia. Karst depression is defined as karst polje (karst field) if the bottom is at least 500 m wide. The bottom of the karst polje consists mostly of Triassic dolomite and limestone covered by Tertiary sediments (loam and sand). The typical form of karst polje is a vanishing stream and continuous steep periphery. The karst stream appears on one side of the polje, flows on the surface and vanishes in the sink holes on the other side. Karst polje is characterized by huge inter-annual water level fluctuation (Gospodarič & Habič 1979; Gams 1998). Loško polje

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary with the Obrh stream is classified as overflow poljes as described above (Gams 1994). The Obrh stream assembles Mali Obrh and Veliki Obrh. Mali Obrh dries out every year. Veliki Obrh has a permanent water supply as well as Obrh in the part after the confluence. When the Obrh stream enters Cerkniško polje it is given a name Stržen. The Stržen stream is characterized by a great water level fluctuation. The lake is formed at Cerkniško polje due to immense floods in spring and autumn. Usually in summers the lake becomes dry. The Lake Cerknica is locus typicus for intermittent lakes and poljes (Gaberščik & Urbanc-Berčič 2002; Gaberščik et al. 2004). The valley of Rak stream still has an uncertain geomorphologic origin. It can be described as an early stage of karst polje. The Rak stream has more or less permanent water supply, but the water regime is highly variable.

Photo 1.1.3 The wetland areas surround the Stržen stream.

The karstic character of the river is also recognized through its geomorphologic features. The underground length of the River Ljubljanica is 38 km. Its whole catchment is 1779 km2 large and almost 1100 km2 of it is karstic. Many springs of Ljubljanica are used as a reserve source of drinking water due to its permanent and substantial amount of water. The River Ljubljanica is exposed to the dispersed pollution from karstic watershed as well as to the point pollution from the settlements and industry. The main source of pollution is the Ljubljana city and its insufficient wastewater treatment plant. This is a huge impact for slow low-land river with low ventilation. In the dry seasons the conditions may become even anoxic (ENCIKLOPEDIJA

SLOVENIJE 1992). The drainage canals and some small tributaries from farmland worsen the situation in a main channel.

Photo 1.1.4 Solid rocks are covered by mosses.

Photo 1.1.5 A still water of the River Ljubljanica reflects a blue sky and a green canopy.

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary 1.1.2 Physical habitat settings Obrh: The most frequent bank structure type was fine inorganic material with vertical slope (42) sediment type was mainly fine inorganic material with solid rocks. The stream flow was mainly stagnant. There was no water present in one river stretch. Five different land use types were recognized, agricultural areas being the most frequent ones. Total length of the surveyed stream was 12.300 km.

Stržen: Fine inorganic material with gentle slope (41) and vertical slope (42) were prevailing bank structures. Ten different sediment types were determined; with the fine inorganic material as the most frequent one. The flow was mostly stagnant. The majority of land use type was determined as wetlands (4). The stream length was 13.570 km.

Rak: Fine inorganic material with gentle (41) and steep slope (42) was found. Solid rocks prevailed as a sediment type. A flow was mostly stagnant or with low velocity (1,2). The land use type was forest (31) and semi-natural areas (32). The stream was very short, 1.860 km only.

Ljubljanica: Connectivity type was classified as 7. The most frequent types of bank structure were fine inorganic material with flat slope, marked as 41, and six variations of sediment type in the river were recognized. The prevailing sediment consisted of gravel and sand (2\3), and fine inorganic material with solid rocks (4\1). Mostly there was no visible flow (1). The most frequent land use type was marked as heterogeneous agricultural areas (24), with town (11) and villages – 11908. Riparian zone was mostly wide. Disturbances on many sites occurred due to reduced vegetation and some clear cuts in urban areas and also in a country - side. Concrete banks were present in the city of Ljubljana.

Overview of surveyed rivers: The most frequent type of bank structure in all rivers was fine inorganic material with gentle slope (41), followed by fine inorganic material with steep slope (42). The prevailing sediment type was fine inorganic material combined with solid rocks on many stretches. Land use type was variable: Obrh and Ljubljanica flow mostly through agricultural landscape. The River Ljubljanica crosses settlements too. The Stržen stream is mainly surrounded by wetland and the Rak stream by the forest.

Previaling sediment type B ank structure Fine inorganic Solid rock Large blocks, Fine inorganic gravel, sand Large blocks Gravel Solid rock Large blocks, fine inorganic Sand Fine inorganic, Organic artificial Artificial

Land use type

Flow class

No flow Artificial Agricultural Dry Low flow Forest Medium flow Wetland

Figure 1.1.1 Share of different habitat settings, bank structure, flow class, prevailing sediment type, and land use type are presented for the four streams together.

1.2 Species composition

In the Obrh stream 44 macrophyte species were observed, 18 hydrophytes and 26 helophytes. No natant species were found, probably because of shallow water. The genus Potamogeton was presented by 4 different species. 3 taxa of Characeae were found in the Mali Obrh stream, Chara sp., Nitella sp. and Tolypella sp.

In the Stržen stream 40 species were observed, 11 hydrophytes and 29 helophytes. The water level of Stržen fluctuated a lot therefore a low number of hydrophytes were found. In the middle and the lower part of the stream Nuphar lutea was found because the water became deep and stagnant.

In the Rak stream we found 35 macrophyte species, 13 hydrophytes and 22 helophytes. The dominant genus colonizing the stream was Potamogeton with six species.

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary In the River Ljubljanica 39 macrophyte species were determined from its source to the Ljubljana city. Besides vascular plants filamentous algae and mosses were added on a list of presence. Among all, 16 species were determined as helophytes and the other as hydrophytes. Lemna minor, L. trisulca, Potamogeton natans, and Nuphar lutea were natant species found in the river. Conditions were favorable for the growth of macrophytes considering the presence of suitable sediment and slow flow that prevailed in the river. Genus Potamogeton prevailed with six species. Filamentous algae were present almost on the whole surveyed area of the river. They indicated a high level of nutrients deriving from the catchment. The majority of hydrophytes, found in the River Ljubljanica, are on the Red list as vulnerable species.

Overview of all rivers: The highest number of species was determined in the Obrh stream (44) and the lowest in the Rak stream (35). The River Ljubljanica has the highest number of hydrophytes due to the permanent water. The highest number of species with an amphibious character was found in Mali Obrh and Stržen because of the variable water regime.

Table 1.2.1 The list of macrophyte species found in the Rivers Obrh, Stržen, Rak, and Ljubljanica.

Macrophy Abbreviati Genus Species Author te type on Red list (HUDS.) Berula erecta COVILLE hyd Ber ere Callitriche spp. hyd Cal spp Ceratophyllum demersum L. hyd Cer dem vulnerable Chara spp. hyd Cha spp Cinclidotus aquaticus (Hedw.)B.S.G. hyd Cin aqu Cinclidotus fontinaloides hyd Cin fon Elodea canadensis L.C.RICH hyd Elo can Fontinalis antipyretica L. hyd Fon ant Glyceria fluitans (L.) R.Br. hyd Gly flu Hippuris vulgaris L. hyd Hip vul vulnerable Hottonia palustris L. hyd Hot pal vulnerable Lemna minor L. hyd Lem min Lemna trisulca L. hyd Em tri vulnerable Myriophyllum verticillatum L. hyd Myr ver vulnerable Myriophyllum spicatum L. hyd Myr spi vulnerable Nasturtium officinale R. BR. hyd Nas off Nitella spp. hyd Nit spp Nuphar lutea (L.) Sibith & Sm. hyd Nup lut vulnerable Polygonum amphibium L. hyd Pol amp vulnerable Potamogeton lucens L. hyd Pot luc vulnerable Potamogeton crispus L. hyd Pot cri Potamogeton filiformis PERS. hyd Pot fil vulnerable

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary Potamogeton natans L. hyd Pot nat Potamogeton pectinatus L. hyd Pot pec Potamogeton perfoliatus L. hyd Pot per vulnerable Potamogeton praelongus Wulf hyd Pot pra endangered W.D.J.Koch ex Potamogeton zizii Roth hyd Pot ziz Ranunculus circinatus SIBITH hyd Ran cir vulnerable Ranunculus trihophyllus CHAIX hyd Ran tri vulnerable Rhynchostegium riparioides (Hedw.)Card. hyd Ryn rip Sagittaria sagittifolia L. hyd Sag sag vulnerable Tolypella spp. hyd Tol spp Utricularia intermedia Hayne hyd Utr int vulnerable Alisma plantago quatica L. hel Ali pla Alisma lanceolatum With. hel Ali lan vulnerable Butomus umbellatus L. hel But umb vulnerable Caltha palustris L. hel Cal pal Carex spp. hel Car spp (L.) Roem. et. Ele pal Eleocharis palustris Schult. hel Equisetum palustre L. hel Equ pal Galium palustre L. hel Gal pal Gratiola officinalis L. hel Gra off vulnerable Iris pseudacorus L. hel Iri pse alpino- Jun alp Juncus articulatus Chaix hel Lycopus europaeus L. hel Lyc eur Lysimachia vulgaris L. hel Lys vul Lythrum salicaria L. hel Lyt sal Mentha aquatica L. hel Men aqu Mentha longifolia (L.) Hudson hel Men lon Myosotis scorpioides L. hel Myo sco Oenanthe fistulosa L. hel Oen fis endangered Phalaris arundinacea L. hel Pha aru (CAV.) TRIN. Phr aus Phragmites australis EX STEUD. hel Plantago altissima L. hel Pla alt Ranunculus flammula L. hel Ran fla Ranunculus lingua L. hel Ran lin vulnerable Rorippa amphibia (L.) Besser hel Ror amp vulnerable Rorippa sylvestis (L.) Besser hel Ror syl Schoenoplectus lacustris (L.) Palla hel Sch lac Senecio paludosus L. hel Sen pal vulnerable Sium latifolium L. hel Siu lat vulnerable Sparganium emersum L. hel Spa eme Sparganium erectum L. hel Spa ere Teucrium scordium L. hel Teu sco vulnerable Typha angustifolia L. hel Typ ang anagalis - Ver ana Veronica aquatica L. hel Veronica beccabunga L. hel Ver bec

Figure 1.3.1 Distribution diagram of macrophytes in the Rivers Stržen, Obrh, Rak and Ljubljanica.

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary The Obrh stream has two branches, the intermittent Mali Obrh stream with 8 stretches and the Veliki Obrh stream) with permanent water (10 stretches). The last part of Obrh (5 stretches) after the confluence rarely dried out. Stržen was divided in 42 stretches and Rak in 8 stretches. The River Ljubljanica was surveyed from its source at Vrhnika to the city of Ljubljana. The river was divided into 22 survey units. A fieldwork was performed in the summer 2004. Hydrophytes Low number of hydrophyte species was observed in Mali Obrh due to intermittent character. Besides the specimens of Characeae family (Chara spp, Nitella spp and Tolypella spp), Ranunculus circinatus was present almost in all stretches. Veliki Obrh was characterized by Fontinalis antipyretica in all stretches, Callitriche spp and P. crispus were present almost in all stretches. Fontinalis antipyretica has wide ecological amplitude (GONCALVES et al. 1992).

High number of hydrophyte species in the Stržen stream develops an amphibious character due to water level fluctuation. The most frequent species were Nuphar lutea and Polygonum amphibium. R. trichophyllus was more abundant and frequent in the first 2/3 of the river.

The species of genus Potamogeton prevailed in the second part of the Rak stream, except of the Potamogeton praelongus, which grew in the first part of the stream.

The most frequent and abundant species of Ljubljanica were Potamogeton natans, Callitriche sp. and Elodea canadensis. They were found in almost all surveyed units. The only free floating species Lemna minor and L. trisulca were present in low abundance in the middle and lower part of the river in sheltered parts with no visible flow. The most diverse communities were found in the 9th and 12th survey units.

Overview of all rivers: The two species frequently presented in all four streams were Hippuris vulgaris and Ranunculus trichophyllus. Both species are characteristic for stagnant and slow flowing water all over Slovenia (Mala flora 1999). The highest number of Bryophytes was found in Rak due to suitable sediment type (stones): Cinclidotus aquaticus, C. fontinaloides and Rhynchostegium ripariodes. The species found only in Ljubljanica were Elodea canadensis, Ceratophyllum demersum, Hottonia palustris, Lema minor, and Lemna trisulca. The species are indicative for the waters, rich with nutrients.

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary Helophytes In Mali Obrh high number of helophytes was observed. Species with an amphibious character Mentha aquatica and Oenanthe fistulosa were present in all survey units, the latter being very abundant. The presence of helophytes in Veliki Obrh was lower due to permanent water. Sparganium spp and Veronica anagallis-aquatica were determined in all stretches.

Mentha aquatica and Myosotis scorpioides dominated in the majority of the stretches in Stržen while Rorippa amphibia was frequent and abundant in the middle part.

Lythrum salicaria was the most frequent helophyte in Rak while Sparganium spp was the most abundant.

Among 16 species of helophytes found in Ljubljanica Sparganium fluitans was the most frequent and the most abundant. Phalaris arundinacea, Lythrum salicaria, and Iris pseudacorus were also frequent, but with the exception of Phalaris arundinacea they appeared in low abundance.

Overview of all rivers: The helophytes that were frequently distributed in all rivers were Mentha aquatica and Spraganium spp. Species of genus Sparganium were not determined because only vegetative organs were present in some stretches. Both species had an amphibious character. Sparganium had mostly submerged form in Ljubljanica. Butomus umbellatus was only found in Stržen and Rak. It grows in standing and slow flowing waters (Mala flora 1999). Ranunculus lingua was rare species and was as same as Oenanthe fistulosa quite frequent in Mali Obrh and Stržen. Senecio paludosus grew in Stržen. It is very characteristic for the whole area of Lake Cerknica.

Figure 1.4.1 RPM diagram of macrophytes in the Rivers Stržen, Obrh, Rak and Ljubljanica.

In Obrh Cladophora spp. had the highest RPM. The value more than 30% was due to the late sampling. Usually it is less abundant. The other two species with RPM over 10% were abundant Ranunculus trichophyllus and Fontinalis antipyretica.

In Stržen Nuphar lutea was dominated with RPM more then 30%.

The highest RPM at almost 40% was reached by Potamogeton perfoliatus in Rak.

Beside filamentous algae there were two other species in Ljubljanica that had higher relative plant mass than other species. Potamogeton natans reached the highest RPM at 23 %, followed by Elodea canadensis at15 %.

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary Overview of all four streams: The highest RPM values in all rivers together reached Potamogeton natans, Nuphar lutea, and Elodea canadensis. The first species had wide ecological tolerance (Preston 1995). P. natans and N. lutea had good conditions for the growth due to stagnant or very slow flow. Their assimilation surfaces are exposed to the direct light and therefore they have high competitive advantage over submerged species. Elodea canadensis is characteristic species for eutrophic habitats (Nichols & Shaw 1986) but can be found in almost all quality classes (Wiegleb 1981) that was also found in the river Ljubljanica.

1.5 Average distribution of species

Figure 1.5.1 MMT/O/d diagram of macrophytes in the Rivers Stržen, Obrh, Rak in Ljubljanica.

The outlined bar extended beyond the black bar in the case of, Potamogeton zizii and P. natans meaning that the species had high mean mass in the stretches where they occurred. This indicates a type 2 distribution. Species P. zizii was found only in Mali Obrh and is new for Slovenia. Nuphar lutea reached high outlined and black bar in Stržen. This means that the species was frequent, widely distributed and abundant. Potamogeton perfoliatus also expressed a type 2 distribution in Rak – the species was present in a small number of stretches with high abundance. Potamogeton natans in Ljubljanica reached both indices MMO and MMT slightly below 3. Filamentous algae, Elodea canadensis, P. lucens, P. pectinatus, and Nuphar lutea reached MMO values above 2 and significantly lower MMT values. MMO indicates the abundance of an individual species only in the survey units where this species was present, while MMT showed that for the whole surveyed area.

The mosses reached the highest d-value in Obrh and in Stržen Polygonum amphibium. All species of mosses were present in all stretches of Rak. In Ljubljanica the highest d-value was calculated for P. natans, Calitriche spp and E. canadensis. The species that reached the d-value more than 0.5 in all streams were Callitriche spp, Hippuris vulgaris, Nuphar lutea, and Ranunculus trichophyllus.

1.6 Overview on species composition and distribution

The three streams Obrh, Stržen, and Rak are karst streams flowing through the karst polje and are characterized by the high water level fluctuation. The prevailing landscape types were wetland, forest, and agricultural areas. The River Ljubljanica flows from its very source in Vrhnika through agricultural landscape, villages and in the lower surveyed part through the city of Ljubljana. The ecosystem is influenced mainly by farming, urbanization and also by industry. The slope of all streams was gentle and flow velocity was from stagnant to moderate. The consequence of flow pattern was an accumulation of sediment that provided suitable substrate for rooted macrophyte species.

The helophyte species dominated in Obrh, Stržen and Rak due to a variable water regime. Consequently, many plant species exhibited an amphibious character.

44 macrophyte species were observed in the Obrh stream, 18 hydrophytes and 26 helophytes. Veliki Obrh has more permanent water than Mali Obrh therefore the number of hydrophytes

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary was higher in it. There were no natant species found, probably because of shallow water. From the confluence further on the water was rich with nutrients. Abundant and frequent appearance of Cladophora spp and Spraganium spp also indicated that status. The main source of nutrients was run off from the agricultural areas and discharges from urban areas, in Veliki Obrh stream. A species Oenanthe fistulosa, very abundant and frequent in Mali Obrh, is in a Red list of endangered species of Slovenia (Ur. list 2002). A special attention deserves Potamogeton zizii found in Mali Obrh. It was determined in Slovenia for the first time.

In the Stržen stream 11 hydrophytes and 29 helophytes were determined. The water level of Stržen fluctuated the most, therefore a low number of hydrophytes were found. Potamogeton crispus, P. lucens, and P. pectinatus were the only species that did not express an amphibious character. Ranunculus lingua a rare species in Slovenia was found frequently in the middle part of Stržen and was very abundant in the last four stretches.

In the Rak stream we found 35 macrophyte species, 13 hydrophytes and 22 helophytes. According to the species distribution the Rak stream could be divided in two parts. The first part of the stream flew through the forest and was colonized by mosses species Cinclidotus aquaticus, C. fontinaloides, and Rhynchostegium riparioides. Potamogeton praelongus that was also abundant there is on the Red list of endangered species of Slovenia (Ur. list 2002). The second part of a stream was surrounded by the open semi natural areas. The presence and abundance of some species indicated its high trophic status: The species Potamogeton lucens, P. natans, P. perfoliatus, Sagittaria sagittifolia and filamentous algae were found there.

In the River Ljubljanica from its source to the city of Ljubljana 39 species of macrophyte were determined. Among all, 16 species were determined as helophytes and 23 as hydrophytes. The length of the surveyed river from the source to the city of Ljubljana is 26 km. The average number of hydrophytes per survey unit was 9.7. At the beginning till the 4th survey unit the flow is visible. Water was transparent inspire of evident inputs from the surroundings. The presence of filamentous algae indicated the inputs of nutrients and other substances. The obvious cover of epiphytes was detected. The deepest part of the riverbed at 3.5 m was empty and coarse inorganic sediment was visible. Erosion of banks was present. The condition in a river was changed radically after the discharge from wastewater treatment plant. Water became turbid and macrophytes disappeared for a distance of hundred meters. Worsening of the river ecosystem was also attributed to the incomplete riparian vegetation due to man impact. The disturbances were observed frequently. The old willow trees that

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary prevailed on banks were cut, and shrubs and invasive herbal plants colonized the banks instead. The depth of the river on these stretches was between 5 and 6 meters, and transparency was 2.5 meters. After each settlement the evidence of man impact was recognized. This became more obvious when the river approached the city of Ljubljana. The greatest change occurred in the city where the river was bifurcated: a part run in a concrete channel made to regulate high water events and the other part follows the original course but is canalized (the length of 4 surveyed units). The deepest part was 3.5 meters and the transparency was 0.5 meter.

B. erecta was abundant in the first part of the surveyed units, while its presence became less frequent and abundant in the middle and lower part. N. officinale, R. trichophyllus and R. circinatus were found in the first and in the middle of surveyed units. P. crispus throve in a great abundance in the upper part. P. lucens appeared in a great abundance in the first surveyed units, while it became less frequent and abundant in the lower part. H. vulgaris, M. verticillatum and P. pectinatus grew in the middle part. P. filiformis and C. demersum were determined only in one survey unit. L. minor and L. trisulca were found in the middle and lower part of the river. P. natans, Callitriche sp., E. canadensis, and P. perfoliatus were present in the majority of the surveyed units.

The most frequent and abundant species of the River Ljubljanica are usually found in loaded waters. P. natans thrives in oligo and eutrophic waters and is ecologically the most tolerant species of genus Potamogeton (Preston 1995). Elodea canadensis is characteristic species for eutrophic habitats (Nichols & Shaw 1986). P. perfoliatus thrives in lakes, reservoirs, canals and rivers. It is confined to meso-eutrophic or eutrophic rivers in a wide variety of plant communities (Preston 1995). Callitriche sp. is a species, characteristic for nutrient medium habitats (Haslam 1985). The presence of nutrients was also shown in great abundance and high frequency of filamentous algae.

Overview of all four streams: The outstanding situation considering species composition was found in Stržen. A highly fluctuated water regime presented inappropriate conditions for hydrophytes. The species, which overcame dry conditions because of their amphibious character, as well as helophytes prevailed. On the contrary, in the River Ljubljanica hydrophytes prevailed since the water table was rather high. A slow flow and a suitable substrate for anchoring besides the high

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary input of nutrients also supported growth of macrophytes. In Obrh three representatives of Characeae were found. Their presence indicated clear water and a fluctuating character of the stream. In the shortest stream Rak, a solid rock was an appropriate substrate for mosses, which colonized the riverbed in a great number and abundance.

1.7 Comparative Aspects

The Rivers Stržen, Obrh, Rak in Ljubljanica are specific mainly due to their hydromorphological characteristics. They have karst character, gentle slope and a wide underground hydrographical net. These outstanding features make comparison with other rivers in the Danube basin unreasonable.

1.8 Highlights

The vegetation period 2004 was characteristic for high precipitation. The rainy events were distributed therefore the year was not recognized as extremely wet. Despite high precipitation Mali Obrh, the majority of Stržen and Rak dried out at the end of the vegetation period. The circumstances did not influence our results. The survey of the River Ljubljanica ended in the city of Ljubljana. The last part of the river was much influenced by anthropogenic factor. The river was canalized and there were dams on both branches. These measures had a great influence on macrophytes. The stream was empty and on the last part of the river after the city only mosses were noticed on the rocks.

1.9 Documentation

1.9.1 Fotodocumentation

No. of Explanation of the motive picture 1 The Mali Obrh stream overgrown with macrophytes 2 Ranunculus lingua in the Mali Obrh stream, rare species in Slovenia 3 Part of the Mali Obrh stream dried out in the peak of the season 4 Pastures around the Mali Obrh stream, the hill Javorniki is seen in the back 5 Old farmhouse along the Veliki Obrh stream 6 The Veliki Obrh stream flows also through cultivated landscape 7 Terrestrial form of Hippuris vulgaris 8 Bridges in the Veliki Obrh stream influence the flow characteristics and the species distribution 9 The Veliki Obrh stream passes by the nice country settlements 10 Rich vegetation in and along the Veliki Obrh stream with flowering Ranunculus

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary trichophyllus 11 Wider view of intermittent Lake Cerknica where the Obrh stream discharges 12 Open water and narrow riparian belt along the Stržen stream 13 Wide open water of the Stržen stream and wood beyond the riparian zone 14 Poor riparian vegetation and slow flow of the Stržen stream 15 The Stržen stream looks like a canal in the certain stretches 16 Phragmites australis is a dominating species in the intermittent Lake Cerknica 17 Flowering Butomus umbellatus in the Stržen stream 18 Nuphar lutea covered the whole surface of the Stržen stream 19 Dense stands of Polygonum amphibium 20 Source of the Rak stream in shadow 21 Abundant aquatic mosses overgrown substratum of the Rak stream 22 Potamogeton perfoliatus prevailed in the stream 23 Potamogeton natans covered the surface on certain stretches 24 Abundance of macrophytes of the Rak stream 25 A view on Veliki naravni most, where the Rak stream disappeared underground 26 The upper part of the River Ljubljanica 27 Helophytes provided a suitable shelter for natant species 28 Rich green canopy of floating pondweed 29 Potamogeton pectinatus was abundant on some stretches 30 Company of the two Callitriche sp. and Elodea canadensis 31 The boat that enabled the survey was a precious vehicle 32 Riparian vegetation on the stretches without a human influence 33 Disturbance on some stretches was recognised by the presence of invasive plants 34 Hottonia palustris in the River Ljubljanica 35 Rich vegetation of the tributary of the River Ljubljanica 36 Man-made improvement of the bank structure 37 Tourists like the voyage on the river by boat 38 The canalisation of the River Ljubljanica in the city of Ljubljana 39 One of the bridges in the the city of Ljubljana

Table 1.9.2: Voucher samples

Genus Species Herbariu Alcohol Photos m Berula erecta x Callitriche spp. x Ceratophyllum demersum Chara sp. x Cinclidotus aquaticus x x Cinclidotus fontinaloides x x Elodea canadensis x Fontinalis antipyretica x x x Glyceria fluitans x Hippuris vulgaris x Hottonia palustris x Lemna minor x Lemna trisulca x Myriophyllum verticillatum x x Myriophyllum spicatum x x

2004, Gaberščik, Germ, Kržič, Urbanc-Berčič MIDCC 1st Year ReportChapter Fehler! Verweisquelle konnte nicht gefunden werden.- Fehler! Verweisquelle konnte nicht gefunden werden. Version: Preliminary Nasturtium officinale x Nitella spp. x Nuphar lutea x Polygonum amphibium x Potamogeton lucens x x Potamogeton crispus x x Potamogeton filiformis Potamogeton natans x Potamogeton pectinatus x x Potamogeton perfoliatus x Potamogeton praelongus x Potamogeton zizii x Ranunculus circinatus x Ranunculus trihophyllus x x Rhynchostegium riparioides x Sagittaria sagittifolia x x Tolypella sp. x Utricularia intermedia x Alisma plantago quatica x Alisma lanceolatum x Butomus umbellatus x Caltha palustris x Carex spp. x Eleocharis palustris x Equisetum palustre x Galium palustre x Gratiola officinalis x Iris pseudacorus x Juncus alpino-articulatus x x Lycopus europaeus x Lysimachia vulgaris x Lythrum salicaria x Mentha aquatica x Mentha longifolia x Myosotis scorpioides x Oenanthe fistulosa x x Phalaris arundinacea x Phragmites australis x Plantago altissima x Ranunculus flammula x x Ranunculus lingua x x Rorippa amphibia x x Rorippa sylvestis Schoenoplectus lacustris x Senecio paludosus x Sium latifolium x Sparganium emersum x x Sparganium erectum x x Teucrium scordium x Typha angustifolia x anagalis - x x Veronica aquatica

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