EFFECT OF LIGHT ON POPULATION SIZE AND HEIGHT OF ALLIUM SCORODOPRASUM L. SPECIMENS IN TURZYN NEAR WYSZKÓW (LOWER WESTERN BUG VALLEY MESOREGION)

Marek T. Ciosek, Janusz Krechowski, Roman Sikorski, Katarzyna Zacharczuk
Department of Botany, University of Natural Sciences and Humanities in Siedlce, Poland

ABSTRACT

The following paper brings the results of a 6-year observation of Allium scorodoprasum population in Turzyn near Wyszków. The species is endangered in Poland (category V) and in the area of South-Podlaska Lowland (category EN). The station is situated in a deciduous forest, on a high slope of the Bug river valley (area ca. 150 m²). In 2005, 2008 and 2011 the number and height of generative and vegetative specimens were investigated. Generative individuals in sunny places were significantly higher compared to vegetative ones. The difference was also confirmed for a station in Siedlce. The effect of light on height of Allium scorodoprasum individuals was also noted. In 2008, in overshadowed places no blooming individuals were observed. The first blooming shoots were observed in 2011, as a result of improvement of light conditions.

Key words: Allium scorodoprasum, distribution, morphology, central-eastern Poland.

INTRODUCTION

During our studies on the flora of Puszcza Biała, a new locality of sand leek Allium scorodoprasum in Turzyn near Wyszków was found. The species occurs on the overshadowed, high slope of the Bug river valley, in the area of ca. 150 m² (10 × 15 m). Allium scorodoprasum belongs to the group of  endangered species in Poland – category V [16], as well as in the  area of South-Podlaska Lowland [7] – category EN. In other regions of Poland the species reaches lower categories of threat [2, 9, 15].

Sand leek is a mediterranean-subcontinental element of flora. The main range of the species includes central-southern and eastern Europe. It also occurs in Scandinavia and in the northern part of Great Britain [10]. Allium scorodoprasum has a scattered range in Poland and is found mainly in central-western and southern part of the country. It has been noted at 184 localities till now [14], of which only nine are situated in central-eastern Poland. The majority of stations in this area are located in the Vistula and Bug river valleys. The species was collected from several localities in Warsaw [13] and in meadows in the Vistula river valley – Śladów near Czerwińsk (leg. Głowacki 1990) and Gołąb in Puławy commune (leg. Głowacki 1995).

The ecological spectrum of the species is quite wide. Allium scorodoprasum is likely to be found in the area of earthworks and other archaeological objects, on roadsides, in parks, graveyards and other ruderal areas, in deciduous forests and dry meadows [1, 4, 5, 8, 12, 13]. According to Zarzycki at al [17] it is a species of fertile habitats (Tr index – 4) of alkaline reaction (R index – 5) with high light requirements (L index – 5, full light). The species reaches light index =  6 in a 9-point scale by Ellenberg et al [6].

In some European countries the sand garlic is domesticated, planted and used in the folk medicine. It has antibacterial properties. The essential oils contained in it stimulate the secretion of digestive enzymes [3].

MATERIALS AND METHODS

A locality of Allium scorodoprasum in Turzyn near Wyszków was recorded in 2005. Phytosociological relevés at the station were made according to the Braun-Blanquet method [11] and repeated in the growing seasons of 2008 and 2011.

In the mentioned years biometric measurements of the individuals were also taken. The specimens were obtained randomly by successive throws with an iron rim, 1 m in diameter. In 2005 the whole population area was well lighted (the area was insolated from the souther side). Ten samples were taken, and then all vegetative and generative specimens were counted as well as the height of 10 randomly chosen shoots was measured. In 2008 light conditions in southern part of the population were very unfavorable. Therefore, the measurements were taken separately from the sunny (A) and overshadowed area (B) – 10 throws with rim at each area. Aiming at protection of the station and monitoring of the effect of light on condition of the population, the overshadowed area was exposed to light by cutting of most of shrubs. The measurements were repeated for the last time in 2011 (separately for area A and B). Moreover, the measurements of 60 randomly chosen Allium scorodoprasum specimens at station in Siedlce (leg. Wierzba 2003, unpublished locality Arcadia Park) were taken in 2011. A statistical analysis of obtained results was performed with the use of the Statistica 10 software. The Mann-Whitney test was applied to investigate the significance of differences between the various paired groups.

RESULTS AND DISCUSSION

The station of Allium scorodoprasum in Turzyn is situated in a degraded oak-hornbeam forest (Tilio-Carpinetum). The tree stand is mainly composed of Acer platanoides,  Tilia cordata  with a little share of Ulmus minor in layer a₂ (Tab. 1). Presence of five geographically alien tree and shrub species is noteworthy. They are: Acer negundo, Robinia pseudoacacia, Larix decidua, Aesculus hippocastanum and Prunus insititia. The first two species, as especially invasive plants, can contribute to fast overshadowing and the disappearance of Allium scorodoprasum population. The increase in the share of Acer negundo in layer a₂ comparing with 2005 (from 2 to 4) is clearly visible. Acer platanoides and A. negundo dominate in the undergrowth (cover degree – 2). In a herb layer prevail species of nitrophilous forest edge communities of ordo Glechometalia hederaceae (class Artemisietea), e.g., Glechoma hederacea, Impatiens parviflora, Urtica dioica, Chelidonium majus, Viola odorata, Galium aparine and Geum urbanum. Totally, 15 species representing that phytosociological unit were recorded. In the period of studies, the increase in the cover degree of Urtica dioica (from 1 to 3) as well as Glechoma hederacea and Impatiens parviflora (from 2 to 3) was noted. Simultaneously, a gradual decrease in the share of species characteristic for the class Querco-Fagetea was observed. Their number decreased from seven 2005, to three in 2011. Ficaria verna still occurs at the station with the little cover value (1), whereas many others, e.g., Gagea lutea, Paris quadrifolia, Viola reichenbachiana and Anemone nemorosa declined. Meadow and synanthropic species dominate in the group of accompanying plants (14 taxon, maximum cover degree – 1).

Cover of tree layer increased from 70% in 2005 to the 80% in 2011. At the same time the density of shrub layer increased from 50% to 70%. In the period under examination cover of herb layer was 100%. Species biodiversity of the station maintains at similar level (40 species in 2005, 39 in 2011). Share of Allium scorodoprasum in herb layer was constant (coverage 3). Simultaneously, the population area increased from 110 m² in 2005 to 160 m² in 2011.

The number of Allium scorodoprasum individuals per 1 m² in Turzyn increased from 30.1 to 35.7 between 2005 and 2011 (Tab. 2). It is mainly correlating with the increase of the number of vegetative shoots in sunny places (from 25.2 to 31.6/m²), whereas concentration of generative individuals was much lower and varied from 3.1 to 5.6/m².

The entire Allium scorodoprasum population was in favourable light conditions in 2005. In 2008, light conditions deteriorated in the southern part of the station (B). In this area were noted exclusively numerous vegetative specimens (37.5 shoots/m²). The area B was exposed to light in 2008 (removal of overshadowing shrubs). Three years later, the first blooming specimens (3.1 per m²) were observed, whereas the number of vegetative shoots decreased to 29.8/m².

The height of generative specimens in 2005 was on average 87 cm (Tab. 2), varying from 69 to 101 cm. Vegetative shoots were much lower – on average 54 cm (variability range 47–66 cm). The same relationships were observed in the successive years – an average height of generative shoots in isolated area (A) in 2008 was 81 cm (extreme values 65–91 cm), and vegetative 51 cm (extreme values 43–61), whereas in 2011 respectively: 86 cm and 68 cm (extreme values 79–98 and 59–75 cm). The significances of differences are confirmed by values of U Mann-Whitney test – respectively:   Z = 3.74, p < 0.001; Z = 3.74, p < 0.001; Z = 2.77, p < 0.001. Similarly, significant differences were observed at station in Siedlce, situated in a little clearing in a city park, in a community of fertile, moderetaly wet oak-hornbeam forest (Tilio-Carpinetum). Generative individuals in sunny places (average height of 80 cm, variability range: 65–91 cm) were much higher than vegetative ones (average height of 38 cm, variability range: 20–48 cm). Value of U Mann-Whitney test: Z = 5.0; p < 0.001. Average height of vegetative shoots in a shade (station in Turzyn) in 2008 was 65 cm (variability range 55–78 cm). That dependence was not observed in the shaded areas.

Monitoring of Allium scorodoprasum stands in Turzyn and Siedlce is still continuing in order to observe the dynamics of changes of the populations and their condition in a longer period of time.

CONCLUSIONS

1. Studies on dynamics of Allium scorodoprasum population carried out in Turzyn  between 2005 and 2011 did not shown the negative changes relating to the population size.
2. Insufficient light conditions strongly affect flowering of Allium scorodoprasum specimens.
3. Generative individuals occurring at sunny areas in Turzyn and Siedlce are significantly higher than vegetative ones.

Accepted for print: 24.11.2014

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.