EFFECT OF THE KIND OF HABITAT ON FLOWERING OF HIEROCHLOË REPENS ( HOST ) SIMONKAI

Studies on fl owering of Hierochloë repens were performed over the years 2005-2007 in fi ve habitats located in Bydgoszcz. The fi rst habitat is a degenerated fresh ryegrass meadow (Arrhenatheretum elatioris). Another one is a degenerated form of initial xerothermic swards (Tunico-Poetum compressae). The third habitat in which the occurrence of Hierochloë repens was found and fl owering was analyzed is sandy sward (Koelerio-Corynephoretea). Yet another habitat is ruderal in character and it was located on the side of the road (Convolvulo-Brometum inermis). The last one is a fertile and moist habitat of elm-ash marshy meadow being gramineous herb fringe communities in character. The evaluation was based on the following analyses: morphological characters of infl orescences (length of infl orescence, stem length, number of infl orescence branches and number of spikelets), stem and infl orescence weight and reproduction effort as well as the share of generative individuals in the population and the number of generative individuals per m2. Differences were found in the structure of Hierochloë repens infl orescence in the habitats analyzed. The biggest infl orescence, in terms of all the characters analyzed, was found in fertile elm-ash marshy meadow, and the smallest in poor xerothermic sward. The highest generative reproduction potential of Hierochloë repens was found in the ruderal habitats. They are the basic potential source of generative diaspora production, which can affect the spreading of this species in Poland.


INTRODUCTION
Hierochloë repens (Host) P.B. or (Host) Simonkai -Flora Europea (1964-1980 is a species which was differentiated from Hierochloë odorata L. and recently found in Poland. Despite a considerable similarity to Hierochloë odorata and Hierochloë australis, it shows different characteristics. It does not have hirsute, in the base of the petiole of the spikelet, and aristate glumelle of staminate fl oret, like Hierochloë australis. Leaves are not hirsute on the top like in Hierochloë odorata. However it has an egg-shaped thick panicle of a much greater number of spikelets than the previous species (even up to 300), and glumelle of bisexual fl ower is adjacently hirsute. The fi rst stand of Hierochloë repens was located in the central part of Bydgoszcz in 1989 (G ę s i ń s k i, 2003). In successive years, new stands were found not only in the city but also in the Kujawsko-Pomorskie Province (R u t k o w s k i , 1997a,b, 1998), and also recently in the south of Poland (R o s t a ń s k i at al. 2005). Hierochloë repens is a xeromezophyte adapted to light sandy soils. It grows in sandy swards, pine forests and on their edges. It also grows in dry meadows, steppe slopes, sands and shrubbery thickets. It is found in gardens close to fences and in the vicinity of lawns (G ę s i ń s k i, 2003). F e d o r o v (1976) locates Hierochloë repens in dry meadows, sands, forest meadows, in thin forests and meadow steppes, at the roads, sometimes on crop plantations. It also accounts for an insignifi cant share of psammophilic typical needlegrass steppes, while on post-steppe fallow it forms a temporary plant community (Z n a k i U k r a i n u , 1977). A wide ecological spectrum of occurrence of the species in Poland, the tendency to enter new habitats demonstrates an expansive character of the species. It was observed, however, that Hierochloë repens shows limited fl owering in some habitats which is not found in others. Assuming that fl owering, generative reproduction is the basis of the species spreading, relevant research was undertaken.
The working hypothesis assumes that based on the evaluation of fl owering of Hierochloë repens it will be possible to defi ne basic sources of production of diasporas of this species in Poland. The aim of this paper is

Krzysztof Gęsiński
Department of Botany and Ecology, University of Technology and Life Science in Bydgoszcz, Prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland e-mail: gesinski@utp.edu.pl to defi ne differences in fl owering depending on the kind of habitat and hence the potential of Hierochloë repens spreading from specifi c kinds of habitats.

MATERIALS AND METHODS
Studies on fl owering of Hierochloë repens were performed over the years [2005][2006][2007] in fi ve habitats located in Bydgoszcz. The fi rst habitat (A) is a degenerated fresh ryegrass meadow (Arrhenatheretum elatioris). Another one (B) is a degenerated form of initial xerothermic swards (Tunico-Poetum compressae). The third habitat (C) in which the occurrence of Hierochloë repens was found and fl owering was analyzed is sandy sward (Koelerio-Corynephoretea). Yet another habitat (D) is ruderal in character and it was located on the side of the road (Convolvulo-Brometum inermis). The last one (E) is a fertile and moist habitat of elm-ash marshy meadow being gramineous herb fringe communities in character.
The evaluation of Hierochloë repens fl owering in selected habitats was based on the following analyses: morphological characters of infl orescences (length of infl orescence, stem length, number of infl orescence branches and number of spikelets), stem and infl orescence weight and reproduction effort as well as the share of generative individuals in the population (it was assumed that an individual was a single overground stem) and the number of generative individuals per m 2 . The analysis of characters of the morphological structure was made based on measurements of 30 infl orescences from each habitat. The results of the measurements were subjected to basic analyses, the arithmetic mean and LSD were determined. To evaluate the similarity of the reproduction potential between populations in the habitats analyzed, a comparison was made based on yearly means with the cluster analy-sis, using the complete linkage method with the use of the Euclidean distance. To develop the present paper, EXCEL, STATISTICA statistical package and Microsoft Word processor were used.

RESULTS
Signifi cant differences were demonstrated in morphological characters of Hierochloë repens infl orescence between the habitats analyzed ( Table 1). The greatest length of the infl orescence was identifi ed in habitats C, E and they were signifi cantly longer than the infl orescences in the other habitats, while the stem length varied more. The shortest one was found in habitat C, followed by B and A, the signifi cantly longest was found in stands D and E. The number of spikelets per infl orescence in the treatments analyzed correlated with the infl orescence length, except for infl orescences Hierochloë repens in stand A where despite a short infl orescence, the number of spikelets was greater, similarly as the number of branches. However, during a comparison of the weight of infl orescence and stem of Hierochloë repens across the habitats it was found that a signifi cantly higher value was identifi ed for the organs in E stand, unlike in the others.
The reproduction effort of Hierochloë repens assumes relatively high values (from 41.8 to 58.2%), irrespective of the kind of the habitat. However, there were also found signifi cant differences in the values of the character studied across the treatments analyzed (Tab. 2). The greatest reproduction effort was found in the individuals in habitats A and C and it was signifi cantly different than B, D and E.
To evaluate the reproduction potential of Hierochloë repens, the percentage of generative individuals in the population was also analyzed. It was demonstra- and shows adaptation to light and sandy soils (F l o r a E u r o p e a , [1964][1965][1966][1967][1968][1969][1970][1971][1972][1973][1974][1975][1976][1977][1978][1979][1980], its mesophilic character also allows it to enter even more fertile habitats of heavy soils and even heavily moist, like elm-ash marshy meadow. It demonstrates unique ecological plasticity in adapting to these conditions not only in terms of morphology, but also generative reproduction. The number of fl orets in the infl orescence is usually connected with the total plant habit (C z a r n e c k a , 1995). In the case of Hierochloë repens, the number of fl orets, and as a result, the weight of the infl orescence, is determined by the number of branches of panicle and so the highest number of fl orets was found in habitat E of elm-ash marshy meadow, and the lowest in the xerothermic sward, while the number of fl orets in this species is closely connected with the number of spikelets. Each spikelet consists of three fl orets, one bisexual fl oret and two staminate fl orets.
When evaluating the reproduction potential of Hierochloë repens, one may state clear differences and similarity of this character between the populations of specifi c habitats. The conditions of fresh ryegrass meadow show a low (a few percent) share of fl owering individuals and their density, similarly as the habitat of sandy sward, while the habitat of xerothermic sward, despite essential differences in the moisture, fertility, as compared with the habitat of elm-ash marshy meadow, also shows similar and even more limited generative reproduction potential, and in the shade conditions under the canopy of the tree, no generative individuals at all and the limitation of reproduction only to vegetative reproduction. Probably the limited insolation under these conditions stimulates such a reaction, which is confi rmed by the report by G r a m m a t i k o p o u l o s et al. (2001), while the highest generative reproduction potential was found in ruderal habitats of Convolvulo-Brometum inermis which can be considered the basic source of the species expansion. Already the presence of this new species in Poland in ruderal habitats, treated as tracks of species spreading, shows its dynamic character, while the fact that in these habitats it demonstrates the greatest generative reproduction potential, over 20-fold higher than in the others, clearly shows its preferences and possibly the main source of the species spreading in Poland.

CONCLUSIONS
1. Differences were found in the structure of Hierochloë repens infl orescence in the habitats analyzed.
2. The biggest infl orescence, in terms of all the characters analyzed, was found in fertile elm-ash marshy meadow, and the smallest in poor xerothermic sward.
3. The highest generative reproduction potential of Hierochloë repens was found in the ruderal habitat.
4. The basic potential source of generative diaspora production, which can affect the spreading of Hierochloë repens in Poland, are ruderal habitats at this stage.