Acta Botanica 2-2015.indd ACTA BOT. CROAT. 74 (2), 2015 265 Acta Bot. Croat. 74 (2), 265–285, 2015 CODEN: ABCRA 25 ISSN 0365-0588 eISSN 1847-8476 DOI: 10.1515/botcro-2015-0024 Diatom communities and vegetation of springs in the south-western Alps MARCELLA MOGNA1,2, MARCO CANTONATI2*, FLORA ANDREUCCI1, NICOLA ANGELI2, GRAZIELLA BERTA1, LUCA MISERERE3 1 University of Eastern Piedmont, Dept. of Science, Technology and Innovation, Viale T. Michel, 11, Alessandria 15121, Italy 2 Museo delle Scienze – MUSE, Limnology and Phycology Research Unit, Corso del Lavoro e della Scienza 3, I-38123 Trento, Italy 3 Via Melchiorre Voli 14, Torino 10135, Italy Abstract – Springs are unique but understudied habitats. Diatom communities have re- ceived some attention but have remained largely unknown in the south-western Alps. We therefore studied the springs of the south-western extreme of the Alpine mountain range. We analysed epilithic and epiphytic assemblages in 48 springs of different ecomorpho- logical types, located on contrasting lithological substrata (carbonate/siliceous). More- over, phytosociological relevés were carried out for carbonate springs. The diatom fl ora consisted of 223 taxa. Most (198) of the taxa were included in the Red List, and 12.5% belonged to threatened categories. Characteristic spring taxa (crenophiles) were present. The ecological preferences of crenophilous diatom species described in the eastern Alps were confi rmed. Diatom species characteristic of the lake-littoral zone were found in pool springs. We observed no signifi cant differences in species richness and diversity between epilithic and epiphytic assemblages, but some species showed a preference for bryophytes, and fi ve occurred in the epibryon only. As regards moisture conditions, 15% of the taxa occurred on wet or temporarily dry sites, and 4% lived mostly outside water bodies. The main environmental factors infl uencing diatom assemblages were pH, conductivity, alti- tude, and shading. The carbonate-substratum crenic vegetation was composed of a mixture of vascular plants and bryophytes, which fi nd their ecological optimum in springs. Bryo- phyte cover was dominant, with the most abundant taxa belonging to the genus Palustri- ella. The vegetation corresponded to the Cratoneuretum commutati association. Keywords: bryophyte, diatoms, epibryon, epilithon, Ligurian Alps, phytosociology, springs, vascular plant * Corresponding author, e-mail: marco.cantonati@muse.it MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 266 ACTA BOT. CROAT. 74 (2), 2015 Introduction Springs provide a habitat for specialised organisms that are e.g. adapted to the relatively constant environments found in permanent springs (THIENEMANN 1924, ODUM 1971, ELLEN- BERG 1996). There are many different spring types, and the early diatom studies mostly concentrated on specifi c habitats: thermal (BÍLÝ 1934, BRABEZ 1941, DELL’UOMO 1986, LE- DERER et al. 1998, KAŠTOVSKÝ and KOMÁREK 2001, HINDÁK and HINDÁKOVÁ 2006, 2007), sa- line (KADLUBOWSKA 1985), tufa (PENTECOST 1991, 1998) and acid (CAMBRA and HINDÁK 1998). More recently springs and especially Alpine springs have attracted the attention of biologists and conservationists due to the high share of endangered species and specialists found in their communities (e.g., CANTONATI 1998, PEINTINGER et al. 2003, CANTONATI et al. 2006, WARNER and ASADA 2006, HÁJEK et al. 2006, 2007, PAYNE and MITCHELL 2007). High-integrity springs provide an opportunity to describe naturally preserved freshwa- ter habitats (WERUM 2001). However such intact springs are becoming increasingly rare. These ecosystems are threatened by nutrient enrichment, exploitation for drinking water and hydropower generation, climate change, pollution, etc. Springs should be carefully monitored as many of them are exposed e.g. to extreme en- vironmental conditions (CANTONATI and SPITALE 2009), and human exploitation (e.g., FRÁNKOVÁ et al. 2009). In terms of biomass production, these ecosystems are dominated by vascular plants and bryophytes (e.g., HÁJKOVÁ and HÁJEK 2003). Although microscopic dia- toms are not major contributors to biomass in springs, they are abundant (POULÍČKOVÁ et al. 2004), and play a key role in the functioning of these systems (CANTONATI et al. 2006). Benthic diatoms are included in the WATER FRAMEWORK DIRECTIVE (EU-WFD 2000) and are regularly used as biological indicators for the environmental assessment of river water quality. The analysis of diatom communities can as well be a useful tool for the correct de- velopment of guidelines for an ecological and sustainable use, and preservation, of water resources. The diatom microfl ora of oligotrophic environments has received renewed atten- tion only in the last fi fteen years. LANGE-BERTALOT and METZELTIN (1996) found as many as 800 taxa in a small number of samples from three oligotrophic lakes at a time when the to- tal diatom fl ora of Central Europe was estimated to comprise 1600 taxa. A Red List has been proposed for Central Europe by LANGE-BERTALOT in 1996. In high mountains, springs often show rich biodiversity due to low nutrient content, moderate wa- ter fl ow, and constant temperature (permanent springs). These habitats provide shelter to endangered and rare taxa (CANTONATI 1998, CANTONATI and SPITALE 2009). The main factors found to infl uence diatom communities are: pH, geochemistry of the substratum, conductivity, current velocity, temperature and shading (CANTONATI et al. 2006). On the other hand, the relative importance of substratum type (lithic or plants) has been debated (CANTONATI et al. 2012 b). FRÁNKOVÁ et al. (2009), for instance, hypothesized a spe- cifi c relationship between Sphagnum and diatom species. Studies analysing diatom assemblages in mountain habitats mainly cover the eastern Alps (CANTONATI 1998, 1999, CANTONATI and ORTLER 1998, CANTONATI and PIPP 2000, CAN- TONATI et al. 2001, CANTONATI and LANGE-BERTALOT 2006, CANTONATI et al. 2006, CANTONATI et al. 2007, CANTONATI and SPITALE 2009, CANTONATI and LANGE-BERTALOT 2010, ANGELI et al. 2010, CANTONATI et al. 2011 a, 2011 b, 2012 a, 2012 b, SPITALE et al. 2012), while data on the western Alps are more sparse and recent (BONA et al. 2008, MOGNA et al. 2007, FALASCO and BONA 2011). DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 267 The aim of this study is to enhance our knowledge and our understanding of spring dia- tom communities in the south-western Alps, providing important information concerning the ecological preferences in relation to the most important environmental variables, and on the occurrence of endangered and rare taxa. Materials and methods The study area is located in the Ligurian Alps, at the south-western extreme of the Alps (Fig. 1). The springs sampled were located in the Pesio and Tanaro Valleys Nature Park (Fig. 1), a protected area of 67.7 km2, and in the Ellero and Corsaglia Valleys that are not included in this Nature Park. Karst phenomena are widespread and prominent in the Park. The most important mountains are: Marguareis (2651 m a.s.l.), Mongioie (2630 m a.s.l.), and Mount of Saline (2612 m a.s.l.). The lithology is very diverse: porphyroids, schists, dif- ferent types of limestones, rhyolites, quartzites. The chemical composition of groundwater refl ects the bedrock chemistry, varying from calcareous waters rich in calcium and magnesium, to acidic waters rich in silica. Morphological, physical, and chemical factors In the summers of 2009–2010 we sampled 48 springs, representing different morpho- logical types: 34 rheocrenes, 9 helocrenes, and 5 limnocrenes, located between 1500 and 2000 m a.s.l. (Tab. 1). The location of each spring was recorded using a GPS. The per cent cover of each substratum (sand, gravel, cobbles, boulders, and detritus) was estimated visu- ally in each spring. Temperature, pH, and conductivity were measured in the fi eld with a multiparametric probe. Chemical analyses including all major ions were carried out by two laboratories: IRIDE of Tortona (Italy), and ARPA (Regional Environmental Protection Agency) of Cu- neo (Italy). Chemical analyses are not available for the following three springs: RF 1477, LG 1510, LG 1500. Fig. 1. Study area: Italy with the Piedmont Region (dark grey); Piedmont Region with the study area marked by a black oval; Pesio and Tanaro Valleys Nature Park (study area, with scale bar). MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 268 ACTA BOT. CROAT. 74 (2), 2015 Ta b. 1 . M ai n m or ph ol og ic al , p hy si ca l a nd c he m ic al c ha ra ct er ist ic s o f t he sp rin gs in th e Li gu ria n A lp s ( Pe sio a nd T an ar o Va lle ys N at ur e Pa rk a nd C or sa gl ia an d El le ro V al le ys ). R – rh eo cr en e, H – h el oc re ne , L – li m no cr en e. S – si lic eo us , C – c ar bo na te . Si te C od e A lti tu de (m a .s. l.) Sp rin g ty pe Su bs tra tu m T (° C ) C on du ct iv ity (μ S cm –1 ) pH Si O 2 N a+ K + C a2+ M g2+ C l– N O 3– C P 13 92 13 92 R S 5. 1 3 0 7. 42 6. 0 < 0. 5 0. 36 4 .8 1 .2 2 0. 32 45 1 C M 1 62 4 16 24 H S 5 8 4 8. 15 6. 8 1. 84 0. 67 15 .9 2. 1 < 0. 2 15 3 C M 1 62 5 16 25 R S 4. 8 8 6 8. 31 6. 7 1. 05 0. 62 16 .0 1 .7 8 0. 22 58 6 M C 1 65 0 16 50 R C 4 19 8 8. 48 2. 5 < 0. 5 0. 42 44 3. 7 0. 45 36 1 M C 1 65 2 16 52 R C 3. 4 20 0 8. 56 2. 3 < 0. 5 0. 43 44 4. 3 0. 46 37 2 M C 1 65 5 16 55 R C 3. 2 20 1 8. 43 2. 4 < 0. 5 0. 28 45 4. 3 0. 40 23 0 R P 18 90 18 90 R C 2 15 8 7. 87 1. 5 < 0. 5 0 .1 69 35 3. 3 0. 26 29 3 R P 18 00 18 00 H C 2 17 0 8. 29 1. 3 < 0. 5 0 .1 58 33 5. 2 0. 21 31 8 C R 1 49 7 14 97 R C 5 18 9 8. 27 4. 4 0. 69 0. 48 42 0 .7 7 0. 39 16 0 C R 1 49 8 14 98 H C 4 20 5 8. 50 4. 5 0. 69 0. 50 46 0 .6 8 0. 37 15 3 D C 15 70 15 70 R C 6. 7 29 5 8. 72 4. 1 < 0. 5 0. 45 50 15 .1 0. 47 24 5 D C 1 62 0 16 20 R C 8. 4 20 0 8. 40 4. 8 < 0. 5 0 .3 3 39 7. 0 0. 35 4 5 IC 1 30 0 13 00 L C 7 64 0 8. 18 8. 4 < 0. 5 < 0. 1 95 30 1. 17 19 2 D C 1 49 5 14 95 R C 7 29 5 8. 45 4. 4 0. 51 0. 35 55 14 .2 0. 42 11 0 R U 1 25 7 12 57 R C 4. 3 18 0 8. 27 3. 3 1. 3 0. 27 51 0. 5 0. 80 26 8 R F 14 77 14 77 H C 8. 1 10 5 7. 39 2. 0 < 0. 51 < 0. 1 30 1 .2 6 0. 41 14 6 C M 1 98 4 19 84 R C 4 13 0 7. 25 2. 5 < 0. 5 < 0. 1 37 0 .8 4 0. 31 14 8 C G 1 85 0 18 50 H C 4. 4 14 0 8. 40 2. 2 0. 5 0. 37 33 5. 2 0. 23 19 6 C V 1 95 4 19 54 H S 4. 3 3 5 7. 15 7. 2 2. 82 0. 63 4 < 0. 5 0. 23 27 3 C V 2 00 6 20 06 R S 4 2 5 7. 02 5. 2 1. 75 0. 50 < 0. 5 1. 7 0. 35 15 1 M T 13 00 13 00 R C 5. 8 12 5 8. 33 3. 7 < 0. 5 0. 48 32 2. 8 0. 26 52 1 SB 1 05 0 10 50 L C 7 17 5 8. 31 2. 4 1. 13 0. 36 43 6. 0 0. 30 56 4 DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 269 Si te C od e A lti tu de (m a .s. l.) Sp rin g ty pe Su bs tra tu m T (° C ) C on du ct iv ity (μ S cm –1 ) pH Si O 2 N a+ K + C a2+ M g2+ C l– N O 3– SE 1 42 0 14 20 R S 8. 9 4 0 7. 3 8. 4 – 0. 3 7 1 0. 3 45 1 G A 1 98 0 19 80 R S 5. 8 4 0 7. 1 5 – 1 7 0. 3 0. 2 2 2 G A 2 00 0 20 00 R S 6. 2 3 0 7. 3 5. 5 – 0. 5 6 0. 3 0. 2 11 2 SE 1 96 0 19 60 L S 5. 8 8 0 7. 5 2. 8 – 0. 2 16 0. 9 0. 2 11 2 SE 2 19 0 21 90 R C 8. 5 12 0 7. 6 2. 9 – 0. 3 27 0. 7 0. 1 2 2 SE 2 14 0 21 40 L C 11 22 0 8 2. 2 – 0. 05 47 1 0. 2 11 2 SE 2 10 5 21 05 L C 10 .3 23 0 8. 2 2. 9 – 1 0 .7 0. 3 0. 3 11 2 SE 2 03 0 20 30 R S 4. 7 18 0 8 2 – 0. 7 19 1 1 22 5 SE 1 76 5 17 65 R S 10 .4 3 0 7. 3 4. 4 – 0. 8 6 0. 8 0. 4 13 5 B A 1 39 0 13 90 R C 5 19 0 7. 8 3 – 0. 5 30 .5 10 .8 0. 6 38 3 B A 1 24 0 12 40 R C 7. 9 21 0 8 3. 4 – 0. 5 33 12 0. 5 45 1 B A 1 20 0 12 00 R C 11 22 0 8 2 – 0. 3 39 8. 6 0. 6 33 8 SE 1 50 0 15 00 R S 5. 6 16 0 7. 5 4. 3 – 0. 5 28 4 0. 9 45 1 SE 1 43 0 14 30 R S 8. 8 9 0 7. 8 5. 5 – 0. 6 13 2 0. 3 45 1 M A 1 93 0 19 30 R C 2. 3 17 0 8. 2 1. 1 – 0. 2 22 7 0. 1 18 0 M A 19 30 19 30 L C 3. 6 11 0 8. 2 2 – 0. 2 14 4 0. 2 20 3 SE 1 51 0 15 10 R C 4. 9 13 0 8 2. 2 – 0. 4 21 4 0. 3 22 5 SB 1 00 0 10 00 H S 15 .6 2 0 6. 6 6 – 0. 2 2 0. 5 0. 3 36 7 SA 2 02 5 20 25 R C 11 .6 19 0 8 2. 4 – 0. 1 42 1. 1 0. 3 24 5 SA 2 00 5 20 05 R C 4. 5 19 0 7. 5 3 – 0. 1 38 1. 3 2 12 2 B A 1 29 0 12 90 R C 6. 5 24 0 7. 8 3. 2 – 0. 5 41 12 0. 5 67 7 B A 1 65 0 16 50 R C 7 23 0 8 2. 9 – 0. 2 39 11 0. 5 45 1 M E 19 06 19 06 L C 8. 6 25 0 7. 5 2. 4 – 2 53 1 3 18 05 C on ce nt ra tio ns o f S iO 2, N a+ , K + , C a2+ , M g2+ , C l– a re in m g L–1 , a nd o f N O 3– i n μg L –1 . MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 270 ACTA BOT. CROAT. 74 (2), 2015 Diatom sampling, preparation, identifi cation, and statistical analyses When possible, we collected diatom communities from different substrata. We sampled epilithon (44 samples), and epibryon (21 samples). Epipelon was sampled with a pipette in only one site (IC 1300), in which no cobbles and bryophytes were found. The epilithon was sampled by randomly collecting at least fi ve cobbles or small boulders (KELLY et al. 1998) in each spring. To study epiphytic communities we sampled along a transect across the dominant bryophytes cutting entire portions of plants that were identifi ed to the species level. The collected material, including the bryophytes, was treated with hydrogen peroxide (100 vol.), and hydrochloric acid (EN 13946, 2003). Cleaned valves were mounted in Na- phrax, two permanent mounts were prepared for each sample, and copies of all slides were deposited in the diatom collection of the Science Museum –MUSE in Trento (Italy). About 400 valves were counted in each sample. The identifi cation and nomenclature mainly fol- lowed KRAMMER and LANGE-BERTALOT (1986–1991), LANGE-BERTALOTand KRAMMER (1989), LANGE-BERTALOT (2001), KRAMMER (1997a, b, 2000–2003, KRAMMER and LANGE-BERTALOT (2004), and WERUM and LANGE-BERTALOT (2004). For single taxa the following were further used: JÜTTNER et al. (2011), LEVKOV (2009), LEVKOV et al. (2013), LOWE et al. (2014). Light microscope observations and micrographs were made using a Zeiss Axioskop 2 (Zeiss, Jena, Germany) with an Axiocam ICC 1 digital camera. Scanning electron microscope (SEM) observations were made primarily at the Department of Life and Environmental Science (DISAV) of the A. Avogadro University of Eastern Piedmont, Alessandria (Italy), using an ESEM (environmental scanning electron microscope) Quanta 200 (FEI, Oland). Further SEM observations were done at the Science Museum – MUSE in Trento, using a LEO XVP (Carl Zeiss SMT Ltd., Cambridge, UK). To investigate diatom ecology, preferences of the species with respect to pH, moisture, and trophism were determined consulting VAN DAM et al. (1994), and the diversity of assem- blages was quantifi ed using the Shannon-Wiener diversity index (SHANNON 1948). The con- servations status of diatom species was evaluated with the German Red List (LANGE-BERTA- LOT 1996). To understand the relationships among environmental parameters and diatom communities, canonical correspondence analyses (CCA) were carried out with the Canoco 4.5 software (TER BRAAK 1998). The biological matrix for the CCA included epiphytic and epilithic samples, excluding taxa with maximum abundance lower than 0.5%. CCA signifi - cance was verifi ed using Monte Carlo permutations test. Vegetation sampling, identifi cation, and statistical analyses The study of vegetation was carried out following the classical phytosociological method (BRAUN-BLANQUET 1964, WESTHOFF and VAN DER MAAREL 1973). The methodologi- cal details are found in PETRAGLIA and TOMASELLI (2007). In the summers of 2010–2011, we performed 28 vegetation relevés in the three morphological types of springs (but on carbonate substratum only) located between 1500 and 2000 m a.s.l. The identifi cation of and nomenclature for vascular plants followed PIGNATTI (1983), TUTIN et al. (1993, 1964– 1980), CORTINI-PEDROTTI (2001; 2006), SMITH (2004) and ALEFFI et al. (2008) for bryo- phytes. Syn-tax 2000 (PODANI 2000) was used to work out sample groups with similar species composition, and to relate these sample groups to the environmental conditions at the sampling sites. DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 271 Results Morphology and hydrochemistry Most of the springs are rheocrenes, and are seasonally infl uenced by pastures. Four are intercepted with pipes for drinking water. The contrasting lithology (carbonate vs. sili- ceous) results in sharp differences in geochemical variables (Tab. 1). Most of the springs (33) emerge on carbonate substratum, with conductivity values from 105 to 640 μS cm–1 (median: 203 μS cm–1), pH values from 7.2 to 8.7, and low silica values (around 2.5 mg L–1). Fifteen springs emerge on siliceous substratum, and show low conductivity values (from 20 to 180 μS cm–1 , median: 66 μS cm–1), pH values from 6.6 to 8.4, and silica values around 5.5 mg L–1. As expected, the calcium and magnesium concentrations were very low in siliceous springs (medians: 10.4 mg L–1 Ca2+, 1.3 mg L–1 Mg2+), and higher in the carbon- ate springs (medians: 39.0 mg L–1 Ca2+, 1.6 mg L–1 Mg2+). Nitrate values were remarkably low (median: 230 μg L–1 N-NO3 –), the only exception being represented by ME1906, which showed a nitrate value of 1805 μg L–1 N-NO3 –. Diatoms: Assemblage composition, ecological preferences, and species richness Overall, 223 diatom taxa belonging to 61 genera were found (On-line Supplement Tab. 1). The genera with the highest number of taxa were: Gomphonema (24), Navicula (14), Eunotia and Nitzschia (13), Cymbella (12), Encyonema (9), Achnanthidium and Psam- mothium (7), Pinnularia and Surirella (6), Planothidium, Diploneis, and Fragilaria (5). The most frequent and abundant species were (Fig. 2): Achnanthidium minutissimum (Fig. 2c), A. pyrenaicum (Fig. 2a) (+ A. rostropyrenaicum), Diatoma mesodon (Fig. 2j) (max abundances > 70%); Cocconeis lineata (Fig. 2g) (max abundance > 60%); Achnanthidium lineare (Fig. 2b), Amphora micra (Fig. 2d), Cymbopleura subaequalis (Fig. 2i), Encyone- ma silesiacum (Fig. 2k), Gomphonema angustatum (Fig. 2o), Meridion circulare (Fig. 2p), Planothidium lanceolatum (Fig. 2m), Tetracyclus rupestris (Fig. 2z) (max abundances 30– 50%); Achnanthidium inconspicuum, A. affi ne, Amphora pediculus, Caloneis fontinalis (Fig. 2e), Cymbella excisiformis (Fig. 2h), Denticula tenuis (Fig. 2f), Cymbella subhelveti- ca, Humidophila contenta (+ H. paracontenta), Humidophila perpusilla, Encyonema lange-bertalotii, Encyonopsis microcephala, Eunotia minor (Fig. 2n), Gomphonema oliva- ceoides, Gomphonema parvulum, Navicula cryptotenella (Fig. 2l), Navicula menisculus, Psammothidium bioretii (Figs. 2t–u), Psammothidium chlidanos, Psammothidium oblon- gellum (Figs. 2r–s), Reimeria uniseriata (Fig. 2v) (max abundances 10–30%). All other species had max abundances < 8%. The Achnanthidium minutissimum species group was the most widespread taxonomic unit (64 samples, maximum abundance 75.8%), accompa- nied by the rheophilic Achnanthidium pyrenaicum (+ A. rostropyrenaicum) (55 samples, maximum abundance 71.1%) and by the crenophilous Diatoma mesodon (46 samples, maximum abundance 80%). Diatom species characteristic of the lake-littoral zone (Figs. 3a–b) were found in limno- crenic springs (e.g., Encyonema caespitosum, Diatoma ehrenbergii (Fig. 3a), Navicula sub- alpina, Planothidium distinctum). Typical mire taxa (Figs. 3c–e), e.g. Encyonema lunatum (Fig. 3c), Frustulia crassinervia (Fig. 3d), Fragilariforma virescens (Fig. 3e), Navicula angusta) were found in helocrenic springs, and typical stream taxa (Figs. 3f–i), e.g., Ach- nanthidium pyrenaicum (Fig. 3i), A. rostropyrenaicum (Figs. 3g–h), Cymbella lange-berta- lotii, Hannaea arcus (Fig. 3f) in rheocrenic springs with medium and high discharge. MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 272 ACTA BOT. CROAT. 74 (2), 2015 Fig. 2. Most frequent and abundant species found in the springs studied: a) Achnanthidium pyrenai- cum (RL valve), b) A. lineare (R valve), c) A. minutissimum (RL valve), d) Amphora micra, e) Caloneis fontinalis, f) Denticula tenuis, g) Cocconeis lineata, h) Cymbella excisiformis, i) Cymbopleura subaequalis, j) Diatoma mesodon, k) Encyonema silesiacum, l) Navicula cryp- totenella, m) Planothidium lanceolatum (RL valve), n) Eunotia minor, o) Gomphonema an- gustatum, p) Meridion circulare, q) Meridion constrictum, r) Psammothidium oblongellum (R valve), s) P. oblongellum (RL valve), t) Psammothidium bioretii (R valve), u) P. bioretii (RL valve), v) Reimeria uniseriata, z) Tetracyclus rupestris. RL – rapheless, R – with raphe. Scale bar = 10 μm. DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 273 Fig. 3. Diatom species frequent and/or abundant in some spring types only. Limnocrenic springs: a) Di- atoma ehrenbergii, b) Cymbella subhelvetica; Helocrenic springs (typical mire taxa): c) Ency- onema lunatum, d) Frustulia crassinervia, e) Fragilariforma virescens. Rheocrenic springs (typ- ical stream, rheophilic taxa): f) Hannaea arcus, g) Achnanthidium rostropyrenaicum (RL valve), h) A. rostropyrenaicum (R valve), i) Achnanthidium pyrenaicum (RL valve). Pseudaerial species: j) Encyonema alpinum, k) Adlafi a bryophila, l) Humidophila contenta, m) H. paracontenta, n) H. perpusilla, o) Orthoseira roeseana. RL – rapheless, R – with raphe. Scale bar = 10 μm. MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 274 ACTA BOT. CROAT. 74 (2), 2015 Moisture-condition preference indicator values could be found for 131 species in the list of VAN DAM et al. (1994): 50% (67 taxa) mainly occurred in water bodies, but also rather regularly on wet and moist surfaces, while 15% occurred on wet and moist or temporarily dry substrata (Figs. 3j–o, 18 taxa, e.g. Adlafi a minuscula, Caloneis tenuis, Humidophila contenta (Fig. 3l) (+ H. paracontenta, Fig. 3m), Eunotia minor, Platessa montana, Psam- mothidium bioretii), 4% of the species were found to be not strictly bound to the aquatic environment and to live nearly exclusively outside water bodies; these pseudaerial species include e.g.: Adlafi a bryophila (Fig. 3k), Humidophila laevissima, H. perpusilla (Fig. 3n), Encyonema alpinum (Fig. 3j), Orthoseira roeseana (Fig. 3o). Out of the taxa found, 198 could be classifi ed according to the German Red List for dia- toms (LANGE-BERTALOT 1996) (Fig. 4): 9% were found to be in the category endangered (e.g., Cavinula pseudoscutiformis (Fig. 4b), Cymbella lancettula, Eucocconeis fl exella (Fig. 4f), Eunotia curtagunowii, E. intermedia (Fig. 4h), E. nymanniana, Navicula angusta, Nei- dium alpinum, Platessa montana (Fig. 4a), Rossithidium petersenii (Fig. 4m)), 13% were on the decrease and 4% were extremely rare (Adlafi a suchlandtii, Cymbella tridentina, Epi- themia goeppertiana, Gomphonema parallelistriatum) (On-line Supplement Tab. 1). The species that could not be classifi ed with the German Red List include several recently dis- covered or described species (e.g., Geissleria gereckei, Eunotia glacialispinosa). Diatom species recently described from springs in the eastern Alps were found (e.g., Cymbella cantonatii (Fig. 4g), C. tridentina (Fig. 4j), Encyonema sublangebertalotii (Fig. 4k), Eunotia glacialispinosa (Fig. 4n), Geissleria gereckei (Fig. 4i), Sellaphora perhibita). The classifi cation of trophic preferences according to the list of VAN DAM et al. (1994) could be made for 134 of 223 taxa, and yielded the following results: 23% oligotraphentic, 12% oligo-mesotraphentic, 13% mesotraphentic, 15% meso-eutraphentic, 21% eutraphen- tic, 15% oligo- to eutraphentic, and 1% hypereutraphentic. According to HUSTEDT in VAN DAM et al. (1994), the pH preferences of 159 of the taxa identifi ed were as follows: 2% acidobiontic, 11% acidophilous, 35% circumneutral, 47% alkaliphilous, 5% alkalibiontic. Diatom species diversity of the springs The Shannon-Wiener diversity index showed no signifi cant differences among the three spring types: the highest diversity index value was found for the helocrenes (median: 3.4), followed by limnocrenic springs (3.2), and rheocrenic sources (3.0). The t-test analyses re- vealed a statistically signifi cant difference between helocrenic and rheocrenic springs (t = 2.14, P = 0.05). There were no signifi cant differences in diversity index between carbonate (median = 3.1) and siliceous springs (median = 3.0). The maximum taxa number (44 taxa) was found in epilithic samples from helocrenic carbonate springs (SE 2140, and SE 2105), while the minimum (15 taxa) was found in epilithic samples from carbonate rheocrenic springs (SE1510). On siliceous substrata the highest and lowest taxa numbers were 34 and 17 re- spectively. There were no signifi cant differences in the number of taxa or the diversity in- dex values between epilithic and epiphytic assemblages but the difference between bryo- phyte samples taken from siliceous and carbonate substratum (3.3 on carbonate, and 2.7 on siliceous substrata) was highly signifi cant. DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 275 Fig. 4. Crenophilous, Red List, and rare diatom species found in the springs studied: a) Platessa montana (R valve), b) Cavinula pseudoscutiformis, c) Delicata minuta, d) Encyonopsis ce- satii, e) Diatoma hyemalis, f) Eucocconeis fl exella (RL valve), g) Cymbella cantonatii, h) E. intermedia, i) Geissleria gereckei, j) Cymbella tridentina, k) Encyonema sublangebertalotii, l) Surirella helvetica, m) Rossithidium petersenii (oblique lighting), n) Eunotia glacialispi- nosa. RL – rapheless, R – with raphe. Scale bar = 10 μm. MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 276 ACTA BOT. CROAT. 74 (2), 2015 Diatom communities and environmental variables The signifi cance of the CCA shown in Fig. 5 was tested with Monte Carlo permutation tests (999 permutations under full model), and found to be highly signifi cant (test of signifi - cance of fi rst canonical axis: eigenvalue = 0.289, F-ratio = 3.628, P-value = 0.0140; test of signifi cance of all canonical axes: trace = 0.809, F-ratio = 1.651, P-value = 0.0010). The proportion of variance explained by Axis 1 was 35.7%, whilst the proportion of variance explained by Axis 2 was 23.5%. Conductivity (–0.53) and pH (–0.93) were signifi cantly correlated to CCA Axis 1, while altitude (–0.79), shading (0.66), and temperature (0.60) were signifi cantly correlated to CCA Axis 2 (Fig. 2). The left part of the biplot contains taxa typical of circumneutral (e.g., Achnanthidium minutissimum, Cymbopleura subaequalis, Diatoma mesodon) and alkaline (Achnanthidium pyrenaicum, Amphora pediculus, Navicula cryptotenella) waters. The right part collects acidophilous taxa (e.g., Eunotia implicata, E. intermedia, E. minor). Altitude was negatively correlated with shading (–0.71). Temperature and altitude were not always negatively correlated, because karstic phenomena are very important in this area and drain the water to lower altitudes. Nitrate concentrations were higher at lower altitudes due to human impacts. Nevertheless, high values were sometimes recorded also at high al- titudes, probably because of the impact of pastures. Fig. 5. Canonical correspondence analysis (CCA): springs’ sampling sites – environmental variables biplot. See table 1. for details about investigated sampling sites. DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 277 Vegetation: Analysis and classifi cation In the 28 relevés, the bryophyte component was dominant, as usual in the Cratoneurion commutati alliance (On-line Supplement Tab. 2). Besides Palustriella commutata, the pres- ence of additional elements belonging to this alliance was also observed (i.e. Saxifraga aizoides, Equisetum variegatum). Some species belonging to the Caricetalia davallianae order were found as well. Cluster analysis (not shown) revealed two main groups. The fi rst represented, in general, communities dominated by bryophytes growing on constantly moist or intermittently sub- merged substrata. Within this fi rst group, two sub-groups could be identifi ed: a. the typical aspect of this community, and b. its Palustriella falcata variant. The second group was re- lated to coenoses which colonize the fringe of springs reached only by water spray and only occasionally directly infl uenced by water. Multivariate analyses (not shown) suggested that the distribution of relevés was related to the presence of water: in particular a group, referred to the fi rst group mentioned above, included species colonizing the submerged area (vascular plants mainly found in water bodies, e.g. Veronica anagallis-aquatica and Caltha palustris). Discussion Our study extended and improved knowledge gained on spring diatom communities in the south-eastern Alps to the south-western Alps, and added several further useful observa- tions. In particular spring diatom communities of the south-western Alps were found to in- clude: 1) crenophilous species (part of which were relatively recently described in the south-eastern Alps); 2) many threatened Red List species; 3) diatom species characteristic of other freshwater habitats (lakes, mires, streams) according to spring typology (limno- crenes, helocrenes, rheocrenes). Patterns and features outlined by means of the analysis of diatom communities were in good agreement with those suggested by explorative analyses on the vascular plant and bryophyte vegetation of carbonate springs. The water quality of the springs sampled is relatively high in most cases. Mineral con- centrations are low: average values of conductivity were 66 μS cm–1 on siliceous and 203 μS cm–1 on carbonate substrata. As confi rmed by the comparison of nitrate values with land-use information, the main impact on water quality derives from pastures. The relatively high species richness (223 taxa in 48 springs) generally confi rms the fi ndings of other studies carried out in the Alps (250 taxa in 30 sampling sites, CANTONATI 1998; 131 taxa in 21 sampling sites, CANTONATI and SPITALE 2009; 197 taxa in 54 sites, GE- SIERICH and KOFLER 2010; 174 taxa in 19 sampling sites, FALASCO and BONA 2011). In agree- ment with studies carried out in similar habitats located on comparable lithological sub- strata (CANTONATI 1998, CANTONATI et al. 2007, GESIERICH and KOFLER 2010, FALASCO and BONA 2011, CANTONATI et al. 2012 b) the most frequent and abundant taxa were: Achnan- thidium minutissimum species complex, and Diatoma mesodon. We found many species that showed a strong affi nity to springs and could therefore be classifi ed as crenophiles (e.g.: Caloneis alpestris, Campylodiscus hibernicus, Cymbella laevis, Delicata minuta, Diatoma hyemalis, Diatoma mesodon, Encyonopsis cesatii, Eu- cocconeis fl exella, Eunotia exigua, Eunotia minor, Eunotia tenella, Meridion circulare, Su- rirella spiralis). Species recently described in the eastern Alps as typical for springs from carbonate bedrock were found, and their ecological preferences could be confi rmed: Cym- MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 278 ACTA BOT. CROAT. 74 (2), 2015 bella tridentina (CANTONATI et al. 2010), Encyonema sublangebertalotii and Eunotia gla- cialispinosa (CANTONATI and LANGE-BERTALOT 2010), Geissleria gereckei (CANTONATI and LANGE-BERTALOT 2009). Most of the springs studied are rheocrenes, the most common spring type in the Alps according to DI SABATINO et al. (1997). The biodiversity and richness analysis of the three spring types yielded high values, e.g. average Shannon-Wiener index value: helocrenes (3.4), limnocrenes (3.1), rheocrenes (3.0). Helocrenes were thus confi rmed to be the most species rich spring type (CANTONATI 1998, GERECKE et al. 2011). In good agreement with previous studies (CANTONATI and SPITALE 2009), we found typi- cal mire taxa (e.g., Encyonema lunatum, Frustulia crassinervia, Fragilariforma virescens, Navicula angusta; CANTONATI et al. 2011 b) in helocrenic springs, and typical stream taxa (e.g., Achnanthidium pyrenaicum, Cymbella lange-bertalotii, Hannaea arcus) in rheocrenic springs with medium and high discharge. Moreover, taxa typical of lake shores (e.g.: Cym- bella subhelvetica, Diatoma ehrenbergii, Encyonema caespitosum, Navicula subalpina; CANTONATI and LOWE 2014) could also be observed in this study in limnocrenic springs. The presence of aquatic plants, especially of bryophytes, increases the heterogeneity of microhabitats, and allows for colonization by high numbers of taxa, confi rming the role of springs as hot spots for biodiversity (CANTONATI 2004, FRÀNKOVÀ et al. 2009). As already observed by BERTRAND et al. (2004), no signifi cant differences in diversity and species richness between epilithic and epiphytic assemblages could be found. Howev- er, we observed that, whilst several species occurred on all substrata, some showed a clear preference for bryophytes, e.g.: Caloneis fontinalis, Diatoma hyemalis, Diploneis kram- meri, Encyonopsis cesatii, Eunotia glacialispinosa, Tetracyclus rupestris. Five species even occurred in the epibryon only: Encyonopsis falaisensis, Eunotia meisteri, Adlafi a bryophila, Tabellaria fl occulosa, Surirella spiralis. Among the diatom taxa found, 223 were included in in the German Red List (LANGE- BERTALOT 1996), 84 were classifi ed as »endangered« or »decreasing«. This fi gure would have been even higher if a more updated version of the Red List had been available. The still high percentage of taxa with unknown conservation status shows the potential of re- gional studies in the Alpine area to contribute to the improvement of biodiversity-conserva- tion oriented knowledge. Geochemical factors were found to be the most important variables for the ordination of the springs studied. The CCA results indicated that diatom community composition was mainly determined by pH, conductivity, temperature, altitude, and shading. Similar results were obtained by other authors, e.g.: CANTONATI (1998) and CANTONATI et al. (2012 b) for springs in the south-eastern Alps (pH, altitude, and shading), POULÍCKOVÁ et al. (2004) for helocrenic springs in the western Carpathians, KILROY et al. (2006) for freshwater habitats in the subalpine zone in New Zealand. NOVÁKOVÁ (2002), studying mires in the Czech Re- public, identifi ed pH and shading as the major environmental determinants; in particular the number of species increased with increasing pH, while shading decreased the number of species. GESIERICH and KOFLER (2010) studied the springs in the central Alps in Austria, and found that pH, altitude, conductivity, and nitrates, were the most relevant differentiating variables of diatom assemblage composition. As concerns the part of the study devoted to vegetation analysis, it must be underlined it was limited to springs on carbonate substratum. We were able to attribute the vegetation DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 279 studied to the Montio Cardaminetea class, typical of springs on carbonate rocks. This class includes the order Montio Cardaminetalia and the assemblage Cratoneurion commutati. The identifi ed plant association is Cratoneuretum commutati, with the constant presence of the characteristic species Palustriella commutata, which is an Asiatic bryophyte colonizing carbonate substrata (DIERSSEN 2001), often with other bryophytes such as Palustriella fal- cata, Brachytecium rivulare and Ptychostomum pseudotriquetrum, forming dense carpets. The Cratoneuretum commutati is an association occurring on permanently moist ground, irrigated by base-rich, calcareous, from oligotrophic to mesotrophic waters. Some species belonging to the Caricetalia davallianae order, which groups plant communities typical of neutral-alkaline bogs (MISERERE et al. 2001), were found as well. Spring habitats show very peculiar ecological features such as low and stable water temperature, high air humidity and high oxygen concentration. These ecological character- istics have a very strong infl uence on spring bryophyte and vascular plant life (ZECHMEISTER and MUCINA 1994). The constancy of these habitat conditions led to the establishment of stenothermic plants, many of them representing relicts of past climatic periods (WILMANNS 1989, ELLENBERG 1996). The presence of bryophytes was an important component of the habitats we studied, in accordance with VITT and WIEDER (2009). The main fi nding of the vegetation study was the identifi cation of the Cratoneuretum commutati association, as re- ported also by TOMASELLI et al. (2011) for the south-eastern Alps and MISERERE et al. (2001) for the Aosta Valley Region. Cratoneuretum commutati is a widely-distributed coenosis, even on ample elevation gradients. Its Palustriella falcata variant colonizes the higher ele- vations, preferring oligotrophic waters (TOMASELLI et al. 2011). Palustriella falcata is a cir- cumboreal bryophyte, which can colonise wet calcareous rocks, springs, and fens (DIERSSEN 2001). Even though vascular plant species were present in higher numbers, bryophytes showed a higher cover value. Only occasionally, particularly on muddy substrata, did species like Chaerophyllum hirsutum, Petasites albus, and Cirsium montanum, show higher cover val- ues (TOMASELLI et al. 2011). A species richness increase, characteristic of spring margins, where tall vascular plants inhibit bryophyte growth (TOMASELLI et al. 2011), could be noted in our data. In conclusion, the high diatom and plant biodiversity found in spring habitats of the western Alps underlines the importance of their preservation, the main impacts being pas- tures causing nutrient inputs and trampling damage by cattle during the summer. Acknowledgements MC was partially funded by the Autonomous Province of Trento while contributing to this study. References ALEFFI, M., TACCHI, R., CORTINI PEDROTTI, C., 2008: Check-list of the hornworts, liverworts and mosses of Italy. Bocconea 22, 5–255. ANGELI, N., CANTONATI, M., SPITALE, D., LANGE-BERTALOT, H., 2010: A comparison between diatom assemblages in two groups of carbonate, low–altitude springs with different lev- els of anthropogenic disturbances. Fottea 10, 115–128. MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 280 ACTA BOT. CROAT. 74 (2), 2015 BERTRAND, J., RENON, J. P., MONNIER O., 2004: Relation »diatomées épiphytes-bryophytes« dans les tourbières du Mont Lozère (France). Vie et Milieu 54, 59–70. BÍLÝ, J., 1934: Píšťanské rozsivky (Additamentum ad fl oram Bacillariearum in thermis Píšťany crescentium) (Diatoms from the thermal springs of Píšťanské). Práce Moravské přírodov. Společnosti 9/1, 1–17 (in Czech). BONA, F., FALASCO, E., FENOGLIO, S., IORIO, L., BADINO, G., 2008: Response of macroinverte- brate and diatom communities to human-induced physical alteration in mountain streams. River Research and Application 24, 1068–1081. BRABEZ, R., 1941: Zur Kenntnis der Algenfl ora des Franzensbader und Sooser Thermalen- bereiches. Beihefte zum Botanischen Centralblatt A 61, 137–236. BRAUN-BLANQUET, J., 1964: Pfl anzensoziologie. 3. Aufl . Springer, Wien. CAMBRA, J., HINDÁK, F., 1998: Green algae from mountain peat-bog in the Eastern Pyrenees (Catalonia, Spain). Biologia 53, 467–480. CANTONATI, M., 1998: Diatom communities of springs in the Southern Alps. Diatom Re- search 13, 201–220. CANTONATI, M., 1999: Distribution and seasonality of the phytobenthos along two mountain spring streams in catchments of contrasting lithology. Bollettino Museo Civico Storia Naturale Venezia 49, 357–367. CANTONATI, M., 2004: Le diatomee di tre sorgenti del Parco Naturale delle Prealpi Giulie (Italia nord-orientale). Gortania. Atti Museo Friulano di Storia Naturale 25, 95–108. CANTONATI, M., ANGELI, N., BERTUZZI, E., SPITALE, D., LANGE-BERTALOT, H., 2012 b: Diatoms in springs of the Alps: spring types, environmental determinants, and substratum. Fresh- water Science 31, 499–524. CANTONATI, M., CORRADINI, G., JÜTTNER, I., COX, E. J., 2001: Diatom assemblages in high mountain streams of the Alps and the Himalaya. Nova Hedwigia 123, 37–62. CANTONATI, M., FÜREDER, L., GERECKE, R., JÜTTNER, I., and COX, E. J., 2012 a: Crenic habi- tats, hotspots for freshwater biodiversity conservation: toward an understanding of their ecology. Freshwater Science 31, 463–480. CANTONATI, M., GERECKE, R., BERTUZZI, E., 2006: Springs of the Alps–sensitive ecosystems to environmental change: from biodiversity assessments to long-term studies. Hydro- biologia 562, 59–96. CANTONATI, M., LANGE-BERTALOT, H., 2006: Achnanthidium dolomiticum sp. nov. (Bacillari- ophyta) from oligotrophic mountain springs and lakes fed by dolomite aquifers. Journal of Phycology 42, 1184–1188. CANTONATI, M., LANGE-BETALOT, H., 2009: Geissleria gereckei sp. nov. (Bacillariophyta) from leaf-litter covered stones of very shaded carbonate mountain springs with ex- tremely low discharge. Phycological Research 57, 171–177. CANTONATI, M., LANGE-BERTALOT, H., 2010: Diatom biodiversity of springs in the Berchtes- gaden National Park (northern Alps, Germany), with the ecological and morphological characterization of two species new to science. Diatom Research 25, 251–280. CANTONATI, M., LANGE-BERTALOT, H., DECET, F., GABRIELI, J., 2011 b: Diatoms in very-shal- low pools of the site of community importance Danta di Cadore Mires (south-eastern Alps), and the potential contribution of these habitats to diatom biodiversity conserva- tion. Nova Hedwigia 93, 475–507. DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 281 CANTONATI, M., LANGE-BERTALOT, H., SCALFI, A., ANGELI, N., 2010: Cymbella tridentina sp. nov. (Bacillariophyta), a crenophilous diatom from carbonate springs of the Alps. Jour- nal of the North American Benthological Society 29, 775–788. CANTONATI, M., LOWE, R. L., 2014: Lake benthic algae: toward an understanding of their ecology. Freshwater Science 33, 475–486. CANTONATI, M., ORTLER, K., 1998: Using spring biota of pristine mountain areas for long term monitoring. Hydrology, Water Resources and Ecology in Headwaters (Proceed- ings of the Headwater’98 Conference held at Merano/Meran, Italy, April 1998). IAHS Publ. 248, 379–385. CANTONATI, M., PIPP., E., 2000: Longitudinal and seasonal differentiation of epilithic diatom communities in the uppermost sections of two mountain spring-fed streams. Verhand- lungen der Internationalen Vereinigung für theoretische und angewandte Limnologie 27, 1591–1595. CANTONATI, M., ROTT, E., PFISTER, P., BERTUZZI, E., 2007: Benthic algae in spring: biodiver- sity and sampling methods. In: CANTONATI, M., BERTUZZI, E., SPITALE, D. (eds.), The spring habitat: Biota and sampling methods. Museo Tridentino di Scienze Naturali, Trento, 77–112. CANTONATI, M., SPITALE, D., 2009: The role of environmental variables in structuring epi- phytic and epilithic diatom assemblages in springs and streams of the Dolomiti Bel- lunesi National Park (south-eastern Alps). Fundamental and Applied Limnology – Ar- chiv für Hydrobiologie 174, 117–133. CANTONATI, M., TAXBÖCK, L., MOGNA, M., SPITALE, D., 2011 a: A fi rst comparison among the diatom communities in spring habitats of carbonate mountain ranges of the Alps. 5th Central European Diatom Meeting (CEDIATOM5), Szczecin, Poland, 70–71. CORTINI PEDROTTI, C., 2001: Flora dei muschi d’Italia. Sphagnopsida, Andreaeopsida, Bryopsida (I parte). Antonio Delfi no Editore, Roma. CORTINI PEDROTTI, C., 2006: Flora dei muschi d’Italia. Bryopsida (II parte). Antonio Delfi no Editore, Roma. DELL’UOMO, A., 1986: Diatoms and other algae from the thermal-sulphur springs of Tripon- zo (Central Italy). Algological Studies 42, 79–91. DI SABATINO, A., GERECKE, R., D’ALFONSO, S., CICOLANI, B., 1997: Prime considerazioni sul- la biodiversità delle sorgenti italiane: la taxocenosi ad acari acquatici (Acari, Actinedid- ia, Hydrachnidia). Società Italiana di Ecologia Atti. 18, 171–174. DIERSSEN, K., 2001: Distribution, ecological amplitude and phytosociological characteriza- tion of European bryophytes. Bryophytorum bibliotheca, Bd. 56: 1–289. Berlin: J. Cra- mer in der Gebrüder Borntraeger Verlagsbuchhandlung. ELLENBERG, H., 1996: Vegetation Mitteleuropas mit den Alpen in ökologischer, dynami- scher und historischer Sicht 5. Aufl . – Ulmer, Stuttgart. EN 13946, 2003: Water quality. Guidance standard for the routine sampling and pretreat- ment of benthic diatoms from rivers, 1–18. EU-WFD (WATER FRAMEWORK DIRECTIVE) 2000: Directive 2000/60/EC of the Eu- ropean Parliament and of the Council of 23. October 2000 establishing a framework for Community action in the fi eld of water policy. Offi cial Journal of the European Com- munities L 327, 1–72. MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 282 ACTA BOT. CROAT. 74 (2), 2015 FALASCO, E., BONA F., 2011: Diatom community biodiversity in an Alpine protected area: a study in the Maritime Alps Natural Park. Journal of Limnology 70, 157–167. FRÁNKOVÁ, M., POULÍČKOVÁ, A., NEUSTUPA, J., PICHRTOVÁ, M., MARVAN, P., 2009: Geometric morphometrics – a sensitive method to distinguish diatom morphospecies: a case study on the sympatric populatons of Reimeria sinuata and Gomphonema tergestinum (Bacil- laryophyceae) from the River Bečva, Czech Republic. Nova Hedwigia 88, 81–95. GERECKE, R., CANTONATI, M., SPITALE, D., STUR, E., WIEDENBRUG, S., 2011: The challenges of long-term ecological research in springs in the northern and southern Alps: indicator groups, habitat diversity, and medium term change. Journal of Limnology 70 (Suppl. 1), 168–187. GESIERICH, D., KOFLER, W., 2010: Epilithic diatoms from rheocrene springs in the eastern Alps (Vorarlberg, austria). Diatom Research 25, 43–66. HÁJEK, M., HORSÁK, M., HÁJKOVÁ, P., DÍTĚ, D., 2006: Habitat diversity of central European fens in relation to environmental gradients and an effort to standardise fen terminology in ecological studies. Perspectives in Plant Ecology, Evolution and Systematics 8, 97–114. HÁJEK, M., TICH Ý, L., SCH AMP, S., ZELENÝ, D., ROLEČEK, J., HÁJKOVÁ, P., APOSTOLOVA, I., DÍTĚ, D., 2007: Testing the species pool hypothesis for mire vegetation: exploring the infl uence of pH specialists and habitat history. Oikos 116, 366. HÁJKOVÁ, P., HÁJEK, M., 2003: Species richness and above-ground biomass of poor and calcareous spring fens in the fl ysch West Carpathians, and their relationships to water and soil chemistry. Preslia 75, 271–287. HINDÁK, F., HINDÁKOVÁ, A., 2006: Cyanobacteria and algae of thermal waters at the Piešťany Spa (Western Slovakia) Bulletin Slovenskej botanickej spoločnosti 28, 21–30 (in Slova- kian). HINDÁK, F., HINDÁKOVÁ, A., 2007: Cyanobacteria and diatoms from thermal waters in Sk- lené Teplice (Central Slovakia). Bulletin Slovenskej botanickej spoločnosti 29, 10–16 (in Slovakian). JÜTTNER, I., CHIMONIDES, J., COX, E. J., 2011: Morphology, ecology and biogeography of di- atom species related to Achnanthidium pyrenaicum (Hustedt) Kobayasi (Bacillario- phyceae) in streams of the Indian and Nepalese Himalaya. Algological Studies 136/137, 45–76. KADLUBOWSKA, J., 1985: Untersuchungen der Stetigkeit der Diatomeengesellschaften aus der Salzquelle, den Limnokrenen und dem Moortümpel. Verhandlungen des Internatio- nalen Verein Limnologie 22, 2834–2837. KAŠTOVSKÝ, J., KOMÁREK, J., 2001: Phototrophic microvegetation of thermal springs in Kar- lovy Vary, Czech Republic. In: ELSTER, J., SECKBACH, J., VINCENT, W.F., LHOTSKÝ, O. (eds.), Algae and extreme environments. Nova Hedwigia 123, 107–119. KELLY, M. G., CAZAUBON, A., CORING, E., DELL’UOMO, A., ECTOR, L., GOLDSMITH, B., GUASCH, H., HÜURLIMANN, J., JARLMAN, A., KAWECKA, B., KWADRANS, J., LAUGASTEE, R., LINDSTRØOM, E. A., LEITAO, M., MARVAN, P., PADISÁK, J., PIPP, E., PRYGIEL, J., ROTT, E., SABATER, S., VAN DAM, H., VIZINET, J., 1998: Recommendations for the routine sampling of diatoms for water quality assessments in Europe. Journal of Applied Phycology 10, 215–224. DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 283 KILROY, C., BIGGS B. J. F., VYVERMAN, W., BROADY P. A., 2006: Benthic diatom communi- ties in subalpine pools in New Zealand: relationships to environmental variables. Hy- drobiologia 561, 95–110. KRAMMER, K., 1997 a: Die cymbelloiden Diatomeen, Teil 1. Allgemeines und Encyonema Part. Bibliotheca Diatomologica 36, 1–382. KRAMMER, K., 1997 b: Die cymbelloiden Diatomeen, Teil 2. Encyonema, Encyonopsis and Cymbellopsis. Bibliotheca Diatomologica 37, 1–469. KRAMMER, K., 2000–2003: Diatoms of Europe. Vol. 1. The genus Pinnularia: 703 pp.; Vol. 3. Cymbella: 584 pp.; Vol. 4. Cymbopleura, Delicata, Navicymbula, Gomphocymbellop- sis, Afrocymbella: 530 pp. H. Lange Bertalot, A. R. G. Gantner Verlag K. G. Ruggell. KRAMMER, K., LANGE-BERTALOT, H., 1986–1991: Süβwasserfl ora von Mitteleuropa. In: ETTL H., GERLOFF, J., HEYNIG, H., MOLLENHAUER, D. (eds.), Bacillariophyceae, Naviculaceae, 2/1, 876. G. Fisher, Stuttgart, New York. KRAMMER, K., LANGE-BERTALOT, H., 2004: Bacillariophyceae 4. Teil: Achnanthaceae, Kri- tische Erganzungen zu Navicula (Lineolatae), Gomphonema. Gesamtliteraturverzeich- nis Teil 1–4 [second revised edition] [With »Ergänzungen und Revisionen« by H. Lan- ge Bertalot]. In: ETTL H., GÄRTNER, G.,GERLOFF, J., HEYNIG, H., MOLLENHAUER, D. (eds.), Süßwasserfl ora von Mitteleuropa. Vol. 2, 1–468. Heidelberg: Spektrum Akademischer Verlag. LANGE-BERTALOT, H., 1996: Rote Liste der limnischen Kieselalgen (Bacillariophyceae) Deutschlands. Schriftenreihen Vegetationskunde 28, 633–677. LANGE-BERTALOT, H., 2001: Diatoms of Europe. Navicula sensu stricto, 10 Genera separat- ed from Navicula sensu lato, Frustulia. Diatoms of Europe 2. A. R. G. Gantner Verlag K. G. Ruggell. LANGE-BERTALOT, H., KRAMMER, K., 1989: Achnanthes, eine Monographie der Gattung mit Defi nition der Gattung Cocconeis und Nachtragen zu den Naviculaceae. Bibliotheca Diatomologica 18, 1–393. LANGE-BERTALOT, H., METZELTIN, D., 1996: Indicators of Oligotrophy. Iconographia Diato- mologica, 2, 1–390. Koeltz Scientifi c Books, Königstein. LEDERER, F., GARDAVSKÝ, A., LUKEŠOVÁ, A., KUBEČOVÁ, K., ČÁPOVÁ, R., LODROVÁ, E., TRO- JÁNKOVÁ, K., 1998: Biodiversity and ecology of algae of mineral springs and peat bogs in National Natural Reserve Soos and in the vicinity of Františkovy Lázně and Marián- ské Lázně. In: LEDERER, F., CHOCHOLOUŠKOVÁ, Z. (eds.), Flóra a vegetace minerálních pramenů a rašeliništ’ NPR Soos, Sborník katedry biologie, 14–58. Západočeská Univer- zita Plzeň (in Czech). LEVKOV, Z., 2009: Amphora sensu lato. In.: LANGE-BERTALOT, H. (ed.), Diatoms of Europe 5, 5–916. A. R. G. Gantner Verlag K. G. Ruggell. LEVKOV, Z., METZELTIN, D., PAVLOV, A., 2013: Luticola and Luticolopsis. In.: LANGE-BERTA- LOT, H. (ed.), Diatoms of Europe 7, 1–697. A. R. G. Gantner Verlag K. G. Ruggell. LOWE, R. L., KOCIOLEK, P., JOHANSEN, J. R., VAN DE VIJVER, B., LANGE-BERTALOT, H., KOPAL- OVÁ, K., 2014: Humidophila gen. nov., a new genus for a group of diatoms (Bacillario- phyta) formerly within the genus Diadesmis: species from Hawaii, including one new species. Diatom Research 29, 351–360. MOGNA M., CANTONATI M., ANDREUCCI F., ANGELI N., BERTA G., MISERERE L. 284 ACTA BOT. CROAT. 74 (2), 2015 MISERERE, L., DAL VESCO, G., BUFFA, G., 2001: Ecologia e distribuzione di Carex brunnes- cens (Cyperaceae) nelle Alpi occidentali italiane. Allionia 38, 175–180. MOGNA, M., BATTEGAZZORE, M., GAGGINO, A. M., MORISI, A., 2007: La diatomea Didymos- phenia geminata (Lyngbye) Schmidt nel F. Po e nel T. Varaita. Invasione preoccupante causata da disturbo antropico o mancanza di conoscenza? Annali Scientifi ci del massic- cio del Monviso 3. Edizione Parchi Naturali Regionali del Monviso La Ville Arvieux. NOVÁKOVÁ, S., 2002: Algal fl ora of subalpine peat bog pools in the Krkonoše Mts. Preslia 74, 45–56. ODUM, E. P., 1971: Fundamentals of Ecology. Saunders, Philadelphia. PAYNE, R. J., MITCH ELL E. A. D., 2007: Ecology of Testate Amoebae from Mires in the Cen- tral Rhodope Mountains, Greece and development of a transfer function for palaeohy- drological reconstruction. Protist 158, 159–171. PEINTINGER, M., BERGAMINI, A., SCHMID, B., 2003: Species–area relationships and nestedness of four taxonomic groups in fragmented wetlands. Basic and Applied Ecology 4, 385–394. PENTECOST, A., 1991: Springs that turn life to stone. New Scientist 21/28, 42–44. PENTECOST, A., 1998: The signifi cance of calcite (travertine) formation by algae in a moss- dominated travertine from Matlock Bath, England. Archiv für Hydrobiologie 143, 487– 509. PETRAGLIA, A., TOMASELLI, M., 2007: Phytosociological study of the snow-bed vegetation in the Northern Apennines (Northern Italy). Phytocoenologia 37, 67–98. PIGNATTI, E. E S., 1983: La vegetazione delle Vette di Feltre. Studia Geobotanica 3, 7–47. PODANI, J., 2000: Simulation of random dendrograms and comparison tests: some com- ments. Journal of Classifi cation 17, 123–142. POULÍČKOVÁ, A., HÁJKOVÁ, P., KŘENKOVÁ, P., HÁJEK, M., 2004: Distribution of diatoms and bryophytes on linear transects through spring fens. Nova Hedwigia 78, 411–424. SHANNON, C. E., 1948: A mathematical theory of communication. Bell System Technical Journal 27, 37–42. SMITH, A. J. E., 2004: The moss fl ora of Britain and Ireland. Cambridge University Press. SPITALE, D., LEIRA, M., ANGELI, N., CANTONATI, M., 2012: Environmental classifi cation of springs of the Italian Alps and its consistency across multiple taxonomic groups. In: CANTONATI, M., FÜREDER, L., JÜTTNER, I., COX, E. J. (eds.), The ecology of springs. Fresh- water Science 31, 563–574. TER BRAAK, C. J. F., SIMILAUER. P., 1998: CANOCO reference manual and user’s guide to canoco for windows software for canonical community ordination (version 4). Micro- computer Power (Ithaca, NY, USA). THIENEMANN, A., 1924: Hydrobiologische Untersuchungen an Quellen (I–IV). Archiv für Hydrobiologie 14, 151–190. TOMASELLI, M., SPITALE, D., PETRAGLIA, A., 2011: Phytosociological and ecological study of springs in Trentino (south-eastern Alps, Italy). Journal of Limnology 70, 65–76. TUTIN, T. G., BURGES, N. A., CHATER, A. O., EDMONDSON, J. R., HEYWOOD, V. H., MOORE, T. M., VALENTINE, D. H., WALTERS, S. M., WEBB, D. A., (eds.) 1993: Flora Europea, 1.2a ed. Cambridge University Press. DIATOMS AND VEGETATION OF SW ALPS SPRINGS ACTA BOT. CROAT. 74 (2), 2015 285 TUTIN, T. G., HEYWOOD, V. H., BURGES, N. A., VALENTINE, D. H., WALTERS, S. M., WEBB, D. A., (eds.) 1964–1980: Flora Europea, 1.5. Cambridge University Press. VAN DAM, H., MERTENS, A., SINKELDAM, J., 1994: A coded checklist and ecological indicator values of freshwater diatoms from The Netherlands. Netherlands Journal of Aquatic Ecology 28, 117–133. VITT, D., WIEDER, R., 2009: Structure and function of bryophyte-dominated peatlands. In: GOFFINET, B., SHAW, A. J. (eds.), Bryophyte biology (2nd ed.), 377. Cambridge Univ. Press. WARNER, B. G., ASADA, T., 2006: Biological diversity of peatlands in Canada. Aquatic Sci- ences 68, 240–253. WERUM, M., 2001: Die Kieselalgengesellschaften in Quellen. Abhängigkeit von Geologie kostenlos und anthropogener Beeinfl ussung in Hessen (Bundesrepublik Deutschland). ISBN 13 978-3-89026-331-1. Wiesbaden. WERUM, M., LANGE–BERTALOT, H., 2004: Diatoms in springs from Central Europe and else- where under infl uence of hydrologeology and anthropogenic impacts. In: LANGE-BERTA- LOT, H. (ed.), Iconographia Diatomologica 13, 1–479. A. R. G. Gantner Verlag K. G., Ruggell. WESTHOFF, V., VAN DER MAAREL, E., 1973: The Braun-Blanquet approach. In: WHITTAKER, R. H. (ed.), Ordination and classifi cation of communities. Handbook of Vegetation Science 5, 617–726. Junk, Den Haag. WILMANNS, O., 1989: Ökologische Pfl anzensoziologie. 4. Aufl . Quelle & Meyer, Heidel- berg. ZECHMEISTER, H., MUCINA, L., 1994: Vegetation of European springs: High-rank syntaxa of Montio-Cardaminetea. Journal of Vegetation Science 5, 385–402.