SEGETAL PLANT COMMUNITIES OF THE TOWN OF SIEDLCE AGAINST A BACKGROUND OF TYPICAL PATCHES OF RURAL AREAS PLANT COMMUNITIES OF THE SIEDLCE UPLAND

Jolanta Marciniuk
Department of Botany, Institute of Biology, University of Podlasie, Siedlce, Poland

ABSTRACT

In the paper the author attempts to carry out a comparison between the floristic composition and structure of plant communities present in cereal crops of the rural areas of the Siedlce Upland and the floristic composition and structure of the analogue plant communities found in the area of Siedlce, which is the biggest town of this geographic mesoregion. Tables of the following syntaxons were analysed in the comparative analysis: Papaveretum argemones, Papaver argemones-Vicia tetrasperma, Vicietum tetraspermae scleranthetosum and Vicietum teraspermae typicum. It was observed that the urban plant communities had a greater floristic variety, a greater participation of perennial and ruderal species, as well as, a more complex phytosociological structure, with the exception of few typical patches, comprising diagnostic species of various syntaxons.

Key words: segetal communities, cereal communities, comparative analysis, the Siedlce Upland .

INTRODUCTION

The floristic composition and structure of segetal phytocoenoses are closely related with a cultivation method [9, 19]. Well-recognized and described weed communities have occurred as a result of the traditional extensive farming that was applied for centuries. Recently introduced new technologies and methods of soil cultivation have lead to many changes in the biotope, including its eutrophisation and toxication. This resulted in a degradation of the previously-formed field communities [1, 5, 6, 15, 16, 23, 24, 25, 26, 27]. Urban agrophytocoenoses form themselves, in most cases, under conditions of lack of cultivation. However, they are also influenced by additional antropogenic factors, which are characteristic for strongly urbanized areas. The following urban factors are considered to have the strongest effect on the plant cover: bad water economics, a high degree of communities fragmentation, a salinization of pavements and tram lines, smokiness caused by carbon dust, poisonous factory gases, and car fumes. Changes in the chemistry of top soil layers caused by these factors, particularly by their salinization, alkalization, and toxication by heavy metals [4] lead, on the one hand, to a decrease in stenotypic characteristic species and to disturbances in the structure of urban plant communities, including segetal ones. On the other hand, as a result of the occurrence of numerous adventative taxa, they lead to an increase in their species variety [7, 20].

In the literature no papers have been reported which deal with a comparative analysis of segetal plant communities forming themselves in urban and rural areas of the same geographic region within a short period of time. In this paper the author attempts to carry out such an analysis in relation to the phytocoenoses connected with the cereal crops in rural areas of the Siedlce Upland and the analogues plant communities located within the administrative borders of Siedlce, which is the biggest town of this geographic mesoregion [8].

MATERIALS AND METHODS

In the paper the synthetic tables of the cereal weed communities, found in the rural areas of the Siedlce Upland by Skrzyczyńska [17] in the period of 1989-1993, are used. Phytosociological releves of the segetal communities occurring within Siedlce were taken in the period of 1996-1991 [10]. This material was partly published in Skrzyczyńska and Marciniuk’s paper [18].

Phytosociological stability and coverage coefficient [14] were determined in order to compare the species composition and structure of segetal communities of the town of Siedlce and the Siedlce Upland. When determining the coverage coefficient, value 1 was taken as a plus. The material coming from the town of Siedlce and from the Siedlce upland was compared in shortened tables of the associations. In the columns, describing differences between the compared communities, the Roman numeral results from a difference in the stability class (S). The Arabic numeral describes differences in average coverage coefficients (D); the value scale was applied after Skrzyczyńska [17] and included in table 1.

Sporadic species were omitted in the phytosociological tables. Species plant names were applied after Mirek and coauthors [13], while the syntaxonomic after Matuszkiewicz [11].

RESULTS

A complete inventory of segetal communities of the rural areas of the Siedlce Upland includes 24 well-characterised plant units [17]. In the Siedlce area there were 4 plant associations, two of which showed a differentiation into subcommunities, variants, and subvariants. There was also one indirect community between the associations and 7 forms of the two communities of non-defined taxonomic position, which did not have documented equivalents in the rural areas of the Siedlce Upland [17]. In general the segetal plant communities of the town are differentiated into 22 communities [10].

In the Siedlce area there was a lack of the four segetal associations found in the rural areas of the mesoregion. They were: Arnoserido-Scleranthetum (Chouard 1925) R. Tx. 1937, Herniario-Polycnemetum Fijałkowski 1967, Centunculo-Anthoceretum punctati (W. Koch 1926) Moor 1936 and Lamio-Veronicetum politae Kornaœ 1950.

Below there are the results of the comparative analysis of the plant association patches and town segetal plant communities presented, with most syntaxonomically similar patches described in the area of the Siedlce Upland. Differences in the floristic composition and structure were presented separately for each community.

List of communieties:

Papaveretum argemones typicum from the Siedlce area was floristically richer in 12 species (on average there were two more species observed in one record) than the analogues community described in the rural areas of the Siedlce Upland (Tab. 2). It was also clearly better represented by characteristic species of the association, alliance, and the order. A stable and quite high participation in the urban phytocoenoses of Descurainia sophia is worth to notice in the characteristic species group of the class Stellarietea mediae. This common species of pioneer ruderal communities from the order of Eragrostietalia minoris occurred very rarely in cereal fields in the rural areas of the mesoregion. In the patches of Papaveretum argemones it was not observed [17].

The participation of antropophytes in the species composition of Papaveretum argemones of both areas compared was identical and reached 51%, while the participation of the perennial species in the patches of the urban association amounted to 23%, and was slightly higher than in the areas of the Siedlce Upland, where it arrived at 22% (Fig. 1).

Relationships between the areas compared in relation to the plant community of Vicia tetrasperma-Papaver argemone (Tab. 3) were similar to those in Papaveretum argemones. Also in this case the plant community from the town area was floristically richer, as in the table there were 5 more species and, on average, in the record there were also 5 more species. It was characterised by a higher-participation stability and coverage of characteristic species of Papaveretum argemones i Vicietum tetraspermae. The association of Aperion spicae-venti and the order Centauretalia cyani were represented by 12 species of the second and a higher stability class in the town community, while in the rural areas 7 of them were observed. The floristic composition of the remaining taxonomic units was similar to that of Papaveretum argemones.

The participation of antropophytes in the floristic composition of the community described was slightly higher in the urban areas, reaching 47%, while in the Siedlce Upland it amounted to 46%. The participation of the perennial species (with the same number of taxons) was higher in the rural areas of the mesoregion, amounting to 28%, and in the town to 25% (Fig. 2).

Vicietum tetraspermae was the most common and most differentiated association of cereal weeds both in the rural areas of the Siedlce Upland and in the area of the biggest city of this mesoregion. Skrzyczyńska [17] distinguished 5 subassociations in the Siedlce Upland, two of which, namely Vicietum tetraspermae scleranthetosum and Vicietum tetraspermae typicum occurred in the town area.

In table 4 there is a comparison between the five variants of Vicietum tetraspermae scleranthetosum, distinguished in the town area, and the typical variant of this subassociation, described in the rural areas of the Siedlce Upland. The urban phytocoenoses were characterized by their greater floristic variety. Only in the variant of Anthemis arvensis, with the same species number in the table, were there, on average, 4 species fewer in one record than in the compared community.