Introduction

The Sternbergia colchiciflora W. & K. (Amaryllidaceae) is a hysteranthous and myrmecochorous bulbous geophyte (Dafni et al. 1981). Its distribution covers North-Africa, Southern Central and Eastern Europe, Anatolia and the Caucasus (CITES 2017). In several countries it is considered rare or sporadic plant species [Slovakia: Májovský and Murín (1977), Čeřovský et al. (1999); Spain: Molero and Montserrat (1983), Lagarde (1990), Morales and Castillo 2004; Ukraine: Didukh (2009); Romania: Dihoru and Negrean (2009); Italy: Brullo et al. (2004), Peruzzi et al. (2006, 2008), Frignani et al. (2009), Croatia: Pavletić (1964), France: Debussche et al. (2006), Georgia: Lachashvili et al. (2015), Turkey: Koçyiğit and Tuna (2016)]. In Hungary it has been a protected plant species since 1982, and its IUCN status is Near Threatened (NT) (Király 2007). In Hungary the species is found sporadically in remnants of dry loess grasslands in the South-Tiszántúl region, and on dry steppe slopes along the Transdanubian Mountains (Király 2009; Bartha et al. 2015). Considerable populations of Sternbergia colchiciflora are living in cemeteries along its distribution range in Hungary (Molnár et al. 2018). This paper presents a remarkable population of the species in grassy traffic islands in a city of Hungary.

Materials and methods

The number of individuals of the newly discovered population in the downtown of the county seat Veszprém (W-Hungary) was estimated once a year during flowering in September 2013 and in August 2015 and 2016. The extension of the investigations, the detailed survey of the number of individuals and accompanying species was carried out on 12 April and between 15 and 27 August 2017. The survey of the distribution of individuals inside the traffic islands was conducted between 28 and 29 March 2018. During this survey, we recorded the distance of 671 individuals from the road and from the sidewalk along transects, which were placed on nine grassy traffic islands between the road and sidewalk (transects began next to the paved road and ended next to the sidewalk). The relative distance of individuals from the road and from the sidewalk was the ratio of its absolute distance from the road or sidewalk and the width of the traffic islands. We used one-sample Kolmogorov–Smirnov test to evaluate whether the relative distance of individuals from the road and sidewalk follows a uniform distribution (R Core Team 2018). The geocoordinates and the altitude of the locality were determined by a Garmin E-Trex Legend GPS handheld device recorded in WGS84 format. Soil samples were collected from root depth (5–15 cm) at three points at the locality. Soil analyses of seven characteristics [pH (KCL), soil plasticity, total salt, calcium carbonate, organic matter, nitrogen, phosphorous and potassium content] were carried out by the accredited laboratory of the Research Institute of Karcag of the Centre for Agricultural and Applied Economic Sciences of University of Debrecen. In this paper, plant names follow the nomenclature used in Király (2009).

Results

A population of c.a. 5000 individuals of Sternbergia colchiciflora on both sides of the road on traffic islands and between the road and the sidewalk was found on 8 September 2013, in Veszprém (Hold street, altitude: 254 m, Fig. 1a). According to the detailed survey of 2017, the species was found along both sides of the Hold street in 200 m length on 14 traffic islands. In this year, tens of individuals were found in the cross of the Hold and Fecske streets on two traffic islands. In 2018 we found the species on four new traffic islands and also on two traffic islands 350 m distance in straight line from the previously found subpopulations in the cross of Haszkovó and Akácfa streets. Altogether 7000 individuals were found on 16 traffic islands with the area of 1250 m2. Area of the different traffic islands varied between 6 and 255 m2 (Table 1). Soil of the habitat can be characterized by a slightly basic pH, with clay, a moderate chalk and high nutrient content (Table 2). The 0.1% salt content of the soil can be attributed to the winter de-icing salt (see also Fekete et al. 2018). Both the increase in the number of colonized traffic islands and the increase in the number of individuals on these traffic islands suggest the spatial spread of the population.

Fig. 1
figure 1

a Occurrence of Sternbergia colchiciflora in downtown of Veszprém; b individuals in buds, with freshly opened flowers and in full bloom (23. 08. 2015); c myrmecochorous seeds with elaiosomes; d flowering individuals on a traffic island (11. 08. 2016). Photographs of A. V. Molnár

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Table 1 Characteristics of grassy roadside and midfield islets (i.e., traffic islands) in downtown of Veszprém, hosting Sternbergia colchiciflora and/or other dry grassland species
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Table 2 Soil characteristics of the site with Sternbergia colchiciflora in Veszprém
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Individuals of Sternbergia colchiciflora show a typical distribution on the traffic islands. The closest individuals were at 2 cm distance from the road edge and 0 cm from the sidewalk edge. Individuals were closer to the sidewalk on average than to the road edge (Fig. 2), and their mean ± SD distance from road edge was 3.0 ± 2.4 m, while from the sidewalk edge 2.3 ± 1.9 m. The least number of individuals was found in the middle of the traffic islands, while in the directions of the two edges of the traffic islands the number of individuals increased, but in the immediate vicinity of road, their frequency decreased (Fig. 2). The relative distance of the individuals from the road edge and from the sidewalk differed significantly from a hypothetical uniform distribution, with higher number of individuals situated closer to the road than expected by chance (One-sample Kolmogorov–Smirnov test p < 0.001).

Fig. 2
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Distribution of Sternbergia colchiciflora individuals along transverse directional transects of traffic islands

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During the detailed botanical survey of the locality in 2017, two other protected species were also found, such as Ranunculus illyricus L. (c.a. 3500 individuals on 15 traffic islands) and Vinca herbacea Waldst. & Kit. (c.a. 350 individuals on nine traffic islands). All three protected species (Ranunculus illyricus, Sternbergia colchiciflora and Vinca herbacea) were co-occurring on seven traffic islands. In addition, we observed the co-occurrence of Sternbergia colchiciflora and Ranunculus illyricus on six more traffic islands. On the surveyed islands, we have found other characteristic species of semi-natural dry grasslands, such as Astragalus austriacus Jacq. (3 islands), Festuca rupicola Heuff. (14 islands), Filipendula vulgaris Moench (6 islands), Muscari neglectum Guss. ex Ten. (5 islands), Petrorhagia saxifraga Link (6 islands), Potentilla arenaria Borkh. (6 islands), Salvia nemorosa L. (2 islands), Sanguisorba minor Scop. (2 islands), Teucrium chamaedrys L. (6 islands), Thesium linophyllon L. (4 islands) and Verbascum phoeniceum L. (1 island). On five traffic islands, there were planted individuals of Acer platanoides L. 4.5–5 m distance from each other with 19–31 cm trunk diameter (approximately 12–20 years old), giving shade to the habitat. In most traffic islands we found many disturbance- and trampling-tolerant species, such as Ballota nigra L., Berteroa incana (L.) DC., Cichorium intybus L., Convolvulus arvensis L., Dactylis glomerata L., Digitaria sanguinalis (L.) Scop., Echium vulgare L., Erigeron annuus (L.) Pers., Erodium cicutarium (L.) L’Hér., Falcaria vulgaris Bernh., Linaria vulgaris Mill., Lolium perenne L., Lotus corniculatus L., Malva neglecta Wallr., Medicago lupulina L. Plantago lanceolata L., Polygonum aviculare L., Portulaca oleracea L., Reseda lutea L., Potentilla argentea L., Silene alba (Mill.) E.H.L. Krause, Taraxacum officinale agg., Trifolium pratense L., Trifolium repens L. and Verbena officinalis L.

Discussion

The origin of the Sternbergia colchiciflora population in Veszprém is not known. The inner road ring in Veszprém (to where the Hold Street belongs) was created 10–15 years ago with lots of earthwork at the area. Thus, it seems that the species was introduced with the soil used during the constructions at that time. The most important anthropogenic effect on the population is mowing, but when this activity is the most intensive, Sternbergia colchiciflora is inactive (see also at Molnár et al. 2018b). Our experiences in August 2016 showed that mowing during the flowering period did not threaten the individuals, due to stubble height, which is higher than the plants (2–5 cm). Occurrence of the species in the frequently mowed grassy areas of other cities (e.g., Budapest, Gellért Hill) is also known (Molnár et al. 2017, 2018b).

Passers-by do not notice the Sternbergia colchiciflora individuals during flowering. However, there were less flowering individuals in 2016 than in previous years; there were individuals present on traffic islands where they were previously absent (Fig. 1d). The observation of the species is difficult by the fact that S. colchiciflora often produces self-pollinating, underground flowers (Soó 1973). According to Peruzzi et al. (2006), the rate of cleistogamy may exceed 70%. During autumn, only above-ground flowering (non-cleistogamous) individuals are detectable. Since the seeds with elaiosome (Fig. 1c) of the species are dispersed by different ant species (see also at Molnár et al. 2018a), it is possible that its local spread is due to the activity of ants; however, it is also possible that we did not notice them before. The role of mowing machines in seed dispersal has also been revealed (Strykstra et al. 1997; Vitalos and Karrer 2009).

According to the information provided by the Municipality of Veszprém, the site is located on the public plot of Veszprém, Hold utca 3219/1. The area is owned by the Municipality of Veszprém. According to the ownership sheet of the area, the cultivation branch is “taken off road”; according to the utility map, there is an electric ground cable under the plants. Roadway and roadside were built 15 years ago, and the bicycle path was built 10 years ago. Since then, the roadway and the roadside have remained unchanged. It seems likely that the soil which contained the individuals and/or seeds of other species typical to semi-natural grasslands has come to the area during the construction of the inner roadway or the bicycle path. The local protection of the species was initiated in August 2015 by the Local Group of Veszprém County No. 18 of Birdlife Hungary. The Municipality of Veszprém did not initiate the procedure for the declaration of protection, because the protected natural value, the habitat and individuals of the natural monument cannot be sustained safely in the given area in the long term. Future road and utility reconstruction, technical improvements and increased traffic load on the internal road ring can significantly reduce the chances of survival.

Conclusion for future biology

The flora of the Eastern European cities is especially diverse compared to the adjacent areas, and this phenomenon is not only due to the diversity of introduced species, but also due to the diversity of the native flora (Kühn et al. 2004). Cities could provide habitats for plant species with local or regional importance (Kantsa et al. 2013), similarly to Sternbergia colchiciflora in Veszprém. The spread of the species detected during recent years may be due to the use of motorized lawn mowers.