ANNALES · Ser. hist. nat. · 29 · 2019 · 1 93 received: 2018-12-11 DOI 10.19233/ASHN.2019.10 SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA Nenad JASPRICA Institute for Marine and Coastal Research, University of Dubrovnik, P.O. Box 83, HR-20000 Dubrovnik, Croatia e-mail: nenad.jasprica@unidu.hr Marija PANDŽA Primary School Murterski Škoji, Put Škole 8, HR-22243 Murter, Croatia Milenko MILOVIĆ “Antun Vrančić“ Grammar School, Put Gimnazije 64, HR-22000 Šibenik, Croatia ABSTRACT A phytosociological investigation of spontaneous vegetation on seven-year-old ferro-manganese and silico-man- ganese slag heaps in southern Croatia showed a predominance of ruderals and weeds (Chenopodietea, Artemisietea vulgaris) and taxa of dry open habitats (Festuco-Brometea, Sedo-Scleranthetea). The limited number and cover of woody taxa seem to indicate an early successional stage in the process of development of natural vegetation. However, we recommend removing the heaps from the area and initiating soil remediation according to Croatian law, EU standards and obligations. Key words: phytosociology, ruderal vegetation, industrial waste, Mediterranean climate, Dalmatia, eastern Adriatic VEGETAZIONE SPONTANEA SU ACCUMULI DI SCORIE NELLA CROAZIA MERIDIONALE SINTESI Lo studio fitosociologico della vegetazione spontanea su accumuli di scorie di ferro-manganese e silico-manga- nese nel sud della Croazia, risalenti a sette anni addietro, ha messo in evidenza una predominanza di specie ruderali e infestanti (Chenopodietea, Artemisietea vulgaris) e di taxa di habitat aridi e aperti (Festuco-Brometea, Sedo-Scle- ranthetea). Inoltre, un limitato numero di taxa arborei e arbustivi, con ridotta copertura, suggerisce l’insediarsi di un primo stadio della successione nel processo di sviluppo della vegetazione. Tuttavia si consiglia la rimozione degli accumuli di scorie dall’area e l’avvio della bonifica dei suoli, come previsto dalle leggi croate e secondo gli standard e gli obblighi dell’Unione Europea. Parole chiave: fitosociologia, vegetazione ruderale, rifiuti industriali, clima mediterraneo, Dalmazia, Adriatico orientale ANNALES · Ser. hist. nat. · 29 · 2019 · 1 94 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 INTRODUCTION The Electrodes and Ferroalloys Factory (TEF) in the city of Šibenik, southern Croatia, is a former factory in which the production of pig iron, steel and ferrous alloys took place almost throughout the 20th century, ceasing in 1995. With the decommissioning of the facilities at the TEF site (total surface area of 22 hectares) various types of waste, such as ferro-manganese and silico- manganese slag, tar, phenolic residues, carborundum, graphite electrode scraps, etc. were left at the site. In the period from May 2010 to February 2011, a total of 140,000 tons of ferro-manganese and silico-manganese slag were moved to the village of Biljane Donje near the city of Zadar (Fig. 1). In recent times, only a smaller area with ca. 6,000 m3 of the slag can still be found at the former TEF site in the city of Šibenik. Slag is typically dumped in heaps with no subsequent remediation. Dumping sites for ash and slag waste represent a major challenge in terms of biological reclamation and introduction of vegetation. This is due to the disadvanta- geous properties of such waste, including the absence of soil organic matter (SOM), as well as nitrogen deficiency, high compaction, poor air-water ratio and high alkaline reaction (Kovář, 2004). The onset and development of vegetation at localities of such origin are important topics in restoration ecology (Rehounkova et al., 2011; Prach et al., 2014. and references therein). Such localities offer a unique opportunity for monitor- ing spontaneous processes of colonization/succession of organisms on these “artificial islands” and following biotic interactions in the process (Prach & Pyšek, 1994). In the NW Balkans, studies of spontaneous vegeta- tion development in these habitats, based on phytoso- ciological research, including description of particular plant associations, have been reported from Bosnia and Herzegovina (Lakušić et al., 1977, 1978; Grgić & Lakušić, 1987) and Montenegro (Vukičević & Avdalović, 1982). In Croatia, such sites are still awaiting phytoso- ciological investigation. The matter is addressed by the present study, which examines spontaneous vegetation on seven-year-old slag heaps in southern Croatia. MATERIAL AND METHODS Study area The study was carried out in southern Croatia, in two areas: 1) the area of TEF situated in the city of Šibenik (43°44’43.1” N, 15°52’56.9” E), and 2) the landfill in the village of Biljane Donje, situated 20 kilometres east of the city of Zadar (44°05’47.9” N, 15°28’55.5” E) (Figs. 1 and 2). The slag heaps on the two sites originated from the production of ferroalloys in TEF, and have not been moved or replaced in the last seven years. The altitude of the sites is ca. 10 and 180 m a.s.l. in Šibenik and Biljane Donje, respectively. The heaps top out at about 1.5(–2) to 15 m above the level of the ground. The region has a typical Mediterranean climate: summers are warm and dry, winters mild and rainy, mean annual temperature 15.0–15.4 °C and mean annual precipitation 773–860 mm (data from the meteorological stations of the Croatian Meteorological and Hydrological Service in Šibenik and Zadar for the 1976–2006 period; Milović, 2008; Jasprica et al., 2015). The vegetation surrounding the landfill in Šibenik is mainly composed of planted Pinus halepensis and urban ruderal plant communities (Milović, 2002). In Biljane Donje, the vegetation sur- rounding the landfill is a mosaic of preserved forest patches (mainly dominated by Carpinus orientalis and Quercus pubescens) and vineyards. In general, the slag on the sites is alkaline (the pH of the substrate in initial successional stages is 8–9), with a low manganese content (MnO < 20 %) and about 30 % of Si produced by upgrading standard alloy through addition of silicon waste from the iron silicon industry at the end of the ferroalloy production process (Oliveira et al., 2017). Data collection Fieldwork was carried out in May 2018. The Braun- Blanquet approach (Braun-Blanquet, 1964; Barkman et al., 1964; Dierschke, 1994) was used for data collection, with category 2 subdivided into 2m, 2a and 2b. Five and four relevés were collected in Šibenik and Biljane Donje, respectively. The plots were selected randomly within each site and the entire surface of the landfills was covered. The size of relevé plots was 25 m2. The Fig. 1: Geographical position of the study areas in southern Croatia, eastern Adriatic. Sl. 1.: Geografska lega raziskanega območja v južni Hrvaški, vzhodni Jadran. ANNALES · Ser. hist. nat. · 29 · 2019 · 1 95 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 nomenclature of plant taxa follows the Flora Croatica Database (Nikolić, 2018). The biological forms were directly verified in the field, labelled with acronyms reported by Pignatti (1982) and based on the classifica- tion by Raunkiaer (1934). Regarding chorological forms, reference was made to Jasprica et al. (2017), as well as monographs used for taxonomic nomenclature. Taxa were associated with vegetation units (classes). The system of characterizing species (mostly for those plants that are considered ‘characteristic species’ of the classes) was mostly derived from Mucina et al. (2016). The nomenclature of vegetation units followed Škvorc et al. (2017). Constant taxa were defined as those with a frequency 30 % within the vegetation unit. Dominant taxa were defined as those occurring in at least 10 % of the relevés of a vegetation unit with a cover value of 25 %. RESULTS There were 64 plant taxa in total (Tab. 1). The veg- etation cover varied from 30 % to 80 %, while stands appeared on slopes ranging from 10° to 80°. The landfills were dominated by Therophytes (57 %) and Hemicryptophytes (28 %). Phanerophytes and Chamaephytes occurred in equal percentages ( 5 % each). Mediterranean floral elements (34 %), followed by a considerable share of Cosmopolitans (16 %) and Fig. 2: Ferro-manganese and silico-manganese slag heaps in the area of the former Electrodes and Ferroalloys Fac- tory in the city of Šibenik (A); details of vegetation with Andrachne telephioides and Dittrichia viscosa in Šibenik (B); heaps in the village of Biljane Donje, Zadar County (C), details of vegetation with Avena barbata and Dittrichia viscosa at the top of a heap in Biljane Donje (D) (Photo: N. Jasprica, May 5, 2018). Sl. 2: Feromanganska in silikomanganska jalovina v predelu nekdanje tovarne elektrod in železovih zlitin v Šibeniku (A); detajl vegetacije z vrstama Andrachne telephioides in Dittrichia viscosa v Šibeniku (B); jalovina v zaselku Biljane Donje v zadrskem okrožju (C), detajl vegetacije z vrstama Avena barbata and Dittrichia viscosa na vrhu jalovine v zaselku Biljane Donje (D) (Foto: N. Jasprica, 5 maj 2018) ANNALES · Ser. hist. nat. · 29 · 2019 · 1 96 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 Relevé No. 1 2 3 4 5 6 7 8 9 Locality Šibenik Biljane Donje Plot size (m2) 25 25 25 25 25 25 25 25 25 Aspect N NE . NE NE N S W W LF FE Slope (°) 10 55 . 70 80 70 70 40 80 Vegetation cover (%) 70 50 70 40 30 60 80 80 80 Total number of taxa 20 16 10 17 17 17 12 21 16 % Chenopodietea T SEU Avena barbata Pott ex Link 3 1 . + + 1 3 2a 2m 88 T MED Echium plantagineum L. + . 2a . . + 3 + + 66 H MED Reseda alba L. . + . . . + 1 + + 55 T MED Bromus madritensis L. 1 . . + + . . . . 33 T MED Desmazeria rigida (L.) Tutin + . . . . + . + . 33 T MED Aegilops neglecta Req. ex Bertol. . + . . + . + . 33 H MED Carduus pycnocephalus L. . . . + . + . r . 33 T MED Lophochloa cristata (L.) Hyl. 2a . . . . . . + . 22 T MED Aegilops triuncialis L. + . . . . . . + . 22 T MED Crepis sancta (L.) Babc. . . . + . . . . + 22 T SEU Geranium purpureum Vill. . . . . 2a . . . + 22 T MED Medicago orbicularis (L.) Bartal. . . . . . . . + + 22 T MED Sonchus asper (L.) Hill ssp. glaucescens (Jord.) Ball . + . . . . . . . 11 Tab. 1: Phytosociological table of vegetation on the ferro-manganese and silico-manganese slag heaps. Abbrevia- tions: LF = life form, FE = floral element. Life forms: Ch - chamaephytes, G - geophytes, H - hemicryptophytes, P - phanerophytes, T - therophytes. Floral elements: MED - Mediterranean; SEU - South European; EA - Euroasian; WS - Cosmopolitan; CUAD - Cultivated and adventive plants; * - Illyrian-Adriatic endemic taxon. Tab. 1: Fitosociološka preglednica vegetacije na feromanganski in slikomanganski jalovini. Okrajšave: LF = življenjska oblika, FE = floristični element. Življenjske oblike: Ch – hamefiti, G – geofiti, H – hemikriptofiti, P – fanerofiti, T – terofiti (enoletnice). Floristični elementi: MED – sredozemski, SEU – južnoevropski, EA – evrazijski, WS – kozmopoliti, CUAD – gojene in adventivne rastline, * - ilirsko-jadranski endemit. Date and location of the relevés/ Datumi in lokalitete popisov: May 5, 2018. Rels. 1-5, Šibenik: Rel. 1. X = 5571400, Y = 4845052; Rel. 2. X = 5571390, Y = 4845085; Rel. 3. X = 5571443, Y = 4845104; Rel. 4. X = 5571441, Y = 4845092; Rel. 5. X = 5571431, Y = 4845006. Rels. 6-9. Biljane Donje, near Zadar: Rel. 6. X = 5538978, Y = 4883653; Rel. 7. X = 5538952, Y = 4883659; Rel. 8. X = 5538959, Y = 4883693; Rel. 9. X = 5538978, Y = 4883713. ANNALES · Ser. hist. nat. · 29 · 2019 · 1 97 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 T MED Urospermum picroides (L.) Scop. ex F.W.Schmidt . . . . . . . . r 11 Festuco-Brometea H EA Melica ciliata L. . + + 1 + 2b + . . 66 T EAF Arenaria leptoclados (Reichenb.) Guss. + . . . . . . r . 22 H * Centaurea spinosociliata Seenus . + . . . . . + . 22 H SEU Sanguisorba minor Scop. ssp. muricata Briq. . . + + . . . . . 22 H SEU Lactuca viminea (L.) J. et C. Presl . . . . . + . . r 22 H MED Tragopogon porrifolius L. . . . . . + . . . 11 T MED Lomelosia brachiata (Sm.) Greuter et Burdet (= Trenastelma palaestinum) . . . . . . 1 . . 11 Artemisietea vulgaris H MED Dittrichia viscosa (L.) Greuter . 2a 2a 1 . 2b 1 2b . 66 H EA Chondrilla juncea L. . . . + + . . + + 44 H WS Reseda lutea L. . . + + + . . . . 33 H EA Picris hieracioides L. . . . . . + . . . 11 T WS Galium aparine L. . . . . . . . . + 11 H EA Cirsium vulgare (Savi) Ten. . . . . . . . . r 11 Sedo-Scleranthetea T WS Medicago minima (L.) Barta + + . . . . . 3 . 33 T WS Cerastium pumilum Curtis ssp. glutinosum (Fries) Jalas + . . . . . . + . 22 T EA Petrorhagia prolifera (L.) P. W. Ball ex Heywood . + . . . . . + . 22 T MED Valantia muralis L. . . . r . . . . . 11 ANNALES · Ser. hist. nat. · 29 · 2019 · 1 98 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 Ch SEU Sedum ochroleucum Chaix . . . . + . . . . 11 Lygeo sparti-Stipetea tenacissimae H MED Reichardia picroides (L.) Roth. . . . . r + . . r 33 T SEU Vulpia ciliata Dumort 2m . . . . + . . . 22 H MED Piptatherum miliaceum (L.) Coss. . 3 . + . . . . . 22 H MED Brachypodium retusum (Pers.) P. Beauv. . + . . . . . . . 11 Papaveretea rhoeadis T CUAD Papaver rhoeas L. . . . . r + + . 1 44 T WS Senecio vulgaris L. . . . . . r . r + 33 T EAF Veronica arvensis L. + . . . . . . . . 11 G WS Convolvulus arvensis L. . . . 2a . . . . . 11 Sisymbrietea T EA Geranium rotundifolium L. + + . . . . . . . 22 T MED Sisymbrium orientale L. + + . . . . . . . 22 T WS Erodium cicutarium (L.) Ľ Hér. + . . . . . . . . 11 T WS Xanthium strumarium L. . . . . . . r . . 11 Stipo-Trachynietea distachyae T MED Linaria simplex (Willd.) DC. + 1 2m 1 + 2m + . . 77 Ch MED Andrachne telephioides L. . . 4 + r . r + 4 66 T MED Psilurus incurvus (Gouan) Schinz et Thell + . . . . . . . . 11 Quercetea ilicis P MED Juniperus oxycedrus L. ssp. oxycedrus . . . + . . . . . 11 P MED Pinus halepensis Mill., juv. . . . . + . . . . 11 G MED Asparagus acutifolius L. . . . . . . r . . 11 ANNALES · Ser. hist. nat. · 29 · 2019 · 1 99 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 Helianthemetea guttati T SEU Crupina crupinastrum (Moris) Vis . . + . + . . . . 22 T MED Medicago coronata (L.) Bartal. + . . . . . . . . 11 T MED Minuartia mediterranea (Link.) K. Malý + . . . . . . . . 11 Thlaspietea rotundifoliae H SEU Scrophularia canina L. ssp. bicolor (Sibth. et Sm.) Greuter . . . 1 . . . . . 11 T MED Crucianella latifolia L. . . . . 2m . . . . 11 Digitario sanguinalis-Eragrostietea minoris T MED Heliotropium europaeum L. . + + + . + + + + 77 Koelerio-Corynephoretea canescentis T EA Minuartia hybrida (Vill.) Schischkin in Komarov + . . . . . . . . 11 Asplenietea trichomanis Ch MED Aurinia sinuata (L.) Griseb. . . . . 2a . . . . 11 Rhamno-Prunetea P WS Rosa canina L. . . . . r . . . . 11 Molinio-Arrhenatheretea H WS Plantago lanceolata L. . . . . . . . + . 11 Others T CUAD Conyza canadensis (L.) Cronquist + + . . . . . . . 22 Fumaria sp. . . + . . . . . . 11 Daucus sp. . . . . . + . . . 11 Anthemis sp. . . . . . . . r . 11 Euroasian plants (13 %), dominated on the landfills. Two non-indigenous species were noted: Papaver rhoeas and Conyza canadensis. The latter species is considered invasive in Croatia (Nikolić et al., 2014). Centaurea spinosociliata was defined as an endemic taxon. The highest number of taxa belonged to the Cheno- podietea (14 taxa), followed by Festuco-Brometea (7), Artemisietea vulgaris (6) and Sedo-Scleranthetea (5). The number of taxa in the relevés ranged between 12 and 21 (average 16). The classes Digitario sanguinalis- Eragrostietea minoris, Koelerio-Corynephoretea canes- centis, Asplenietea trichomanis, Rhamno-Prunetea and Molinio-Arrhenatheretea were represented by one taxon each, mostly with a low cover or frequency. The dominant taxa were as follows: Avena barbata, Echium plantagineum, Medicago minima, Piptatherum miliaceum and Andrachne telephioides. Constant taxa were: Avena barbata, Echium plantagineum, Reseda alba, Bromus madritensis, Melica ciliata, Dittrichia viscosa, Chondrilla juncea, Reseda lutea, Medicago ANNALES · Ser. hist. nat. · 29 · 2019 · 1 100 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 minima, Reichardia picroides, Papaver rhoeas, Senecio vulgaris, Andrachne telephioides, Linaria simplex and Heliotropium europaeum. DISCUSSION In the present study, spontaneous vegetation on seven-year-old slag heaps consisted of a relatively low number of taxa. Although we did not study vegetation dynamics, emergence of fast growing annual plant taxa and biennial hemicriptophytes was expected in the first few years, as established in similar studies (Řehounková et al., 2011, and references therein). Transport of dia- spores from the surrounding landscape, mainly through zoochory and anemochory, is among the factors govern- ing the development of plant communities in the initial stages of succession (Vaňková & Kovář, 2004). Seeds of plants are sometimes also carried into the heaps by humans during the heaping process. No bryophytes were found in our study, contrarily to the findings of Grgić & Lakušić (1987), who investigated succession processes on spoil heaps in Bosnia and Her- zegovina. This may be generally attributed to the warm and dry Mediterranean climate and/or specific physical and chemical properties of steel slag in a slag heap. In our case, ruderals and weeds (Chenopodietea, Artemisietea vulgaris) and taxa of the dry open habitats (Festuco-Brometea, Sedo-Scleranthetea) were dominant. In this study, contrary to the findings of Lakušić et al. (1977), who described some plant associations in the heaps (Sedo-Scleranthetea), no characteristic set of taxa was established. The most common taxa from the sites studied were also found in the urban ruderal communi- ties of the surroundings, both in the cities of Šibenik and Zadar (Milović, 2002; Milović & Mitić, 2012) and their environs (Jasprica et al., 2017). In general, but not stud- ied here, the presence of the surrounding vegetation and variations in the species pool could also play a role in the different floristic composition and subsequent com- munity transitions on the sites (Vukičević & Avdalović, 1982; Grgić & Lakušić, 1987; Otto et al., 2006). Both the low number and low cover of woody taxa appear to indicate an early successional stage in the process of the development of natural vegetation. Steel slag is highly reactive and when exposed to rainwater it is known to release ecotoxic metals into the sur- rounding water bodies and soils (Meng & Liu, 2000; Oliveira et al., 2017). These biotopes may thus host only a fraction of the potential colonizers (Heckenroth et al., 2016). In summary, this study adds to the base of informa- tion on the structure of vegetation communities on industrial waste deposits in the Mediterranean climate. Nevertheless, given the relatively small area studied and low number of relevés, the results should be considered in the context of anthropogenic influences occurring as a generalized phenomenon throughout the Mediter- ranean Basin and elsewhere. Taking into account the origin, properties and locations of this waste material, we recommend removing the heaps from the area and undertaking soil remediation according to Croatian law, EU standards and obligations. ACKNOWLEDGEMENTS The authors thank Steve Latham (UK) for improving the English and Massimo Terzi for Italian translation of the abstract. Thanks are also extended two anonymous reviewers whose observations improved the quality of the final version of the manuscript. ANNALES · Ser. hist. nat. · 29 · 2019 · 1 101 Nenad JASPRICA et al.: SPONTANEOUS VEGETATION ON SLAG HEAPS IN SOUTHERN CROATIA, 93–102 SPONTANA VEGETACIJA NA JALOVINAH V JUŽNI HRVAŠKI Nenad JASPRICA Institute for Marine and Coastal Research, University of Dubrovnik, P.O. Box 83, HR-20000 Dubrovnik, Croatia e-mail: nenad.jasprica@unidu.hr Marija PANDŽA Primary School Murterski Škoji, Put Škole 8, HR-22243 Murter, Croatia Milenko MILOVIĆ “Antun Vrančić“ Grammar School, Put Gimnazije 64, HR-22000 Šibenik, Croatia POVZETEK Fitosociološka raziskava spontane vegetacije na sedemletni feromanganski in silikomanganski jalovini v južni Hr- vaški je pokazala prevladovanje ruderalnih rastlin in plevelov (Chenopodietea, Artemisietea vulgaris) ter vrst odprtih habitatov (Festuco-Brometea, Sedo-Scleranthetea). Omejena pokrovnost gozdnih taksonov kaže na zgodnji stadij sukcesije v procesu razvoja naravne vegetacije. 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