Synanthropic communities with Dactylis glomerata L. in the Kursk Region

The results of the studies of synanthropic vegetation in Kursk Region (area is 29 800 sq. km), that is located between 50°54′–52°26′ N and 34°05′–38°31′ E, are given. Zonal vegetation is represented by broad-leaved forests on dark-gray forest soils and meadow steppes on chernozems. Synanthropic vegetation was being studied since 2003. 58 relevés were performed in the city of Kursk and few district centers of Kursk Region. The data were treated by IBIS 7.2 software package (Zverev, 2007). Classification is carried out according to Braun-Blanquet approach, the names of the higher syntaxa follow to «Vegetation of Europe…» (Mucina et al., 2016). Ecological conditions, such as soil moisture, richness in mineral nitrogen, light were assessed with the use of average values by H. Ellenberg et al. (1992) ecological scales while hemero­biality with use of average values of N. G. Ilminskikh (1993) ecological scale and processed by IBIS software (Zverev, 2007). As a result, 2 new associations of synanthropic ve­getation were described. Their communities are widely distributed in anthropogenic habitats within the study area. Ass. Arrhenathero elatioris–Dactylidetum glomeratae (Arepieva 2015) ass. nov. et stat. nov. hoc loco (Table 2, relevés 1–35; nomenclature type (holo­typus) is relevé 19 in the paper by L. A. Arepieva (2015: 102, Table 34), it corresponds to relevé 4 ­(author’s number — 37) in Table 2 in this article) refers to the alliance Convolvulo arvensis–Agropyrion repentis Görs 1967, order Agropyretalia intermedio–repentis T. Müller et Görs 1969, class Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow 1951. Diagnostic species are Arrhenatherum elatius and Dactylis glomerata. Two variants are distinguished within the association. Communities of var. typica (Table 2, rele­vés 1–19; Fig. 1) are described on sunny sites. Communities of var. Glechoma hederacea (Table 2, relevés 20–35; Fig. 2) are often formed in partially shaded habitats under strong anthropogenic impact, that’s why species of the order Arctio lappae–Artemisietalia­ ­vulgaris Dengler 2002 and the class Sisymbrietea Gutte et Hilbig 1975 are more common there. Previously (Arepieva, 2015) we considered this association decribed in the Kursk city as subass. Convolvulo arvensis–Elytrigietum repentis Felföldy 1943 dactylidetosum glomeratae Arepieva 2015. Presently, its rank is rised up to the аssociation for the following reasons: this syntaxon has a wide area of distribution, as the studied communities are common throughout the region, and it good enough differs of the other syntaxa of the alliance Convolvulo arvensis–Agropyrion repentis that are known in our region. Synoptic table (Table 3), value ranges of ecological factors for аssociations (Fig. 3) and DCA-ordination diagram (Fig. 4) demonstrate the differentiation of the syntaxa. The differences of this аssociation of those close to it in composition known in other regions (ass. Convolvulo arvensis–Elytrigietum repentis in Czech Republic, ass. Agropyro repentis–Dactylidetum glomeratae Ubaldi 1976 em. Ubaldi, Puppi et Speranza 1983 in Italy, ass. Geranio tuberosae–Dactylidetum Korzh. et Kljukin 1990 in Ukraine) are discussed. Among syntaxa of the meadow vegetation the most similar in species composition to it is subass. Arrhenatheretum elatioris dactylidetosum glomeratae Nowiński 1967 (alliance Arrhenatherion elatioris Luquet 1926, order Arrhenatheretalia elatioris Tx. 1931, class Molinio-Arrhenatheretea Tx. 1937) in Poland. The syntaxon differentiations are shown in Table 4. In Kursk Region close to the described association is ass. Anthoxantho–Agrostietum tenuis Sillinger 1933 (alliance Cynosurion cristati Tx. 1947, order Arrhenatheretalia elatioris Tx. 1931, class Molinio-Arrhenatheretea Tx. 1937). Ass. Glechomo hederaceae–Dactylidetum glomeratae ass. nov. hoc loco (Table 2, relevés 36–58; nomenclature type (holotypus hoc loco) — relevé 41 (author’s number — 650); Fig. 5) belongs to the alliance Arction lappae Tx. 1937, order Arctio lappae–Artemisietalia vulgaris Dengler 2002, class Epilobietea angustifolii Tx. et Preising ex von Rochow 1951. Diagnostic species are Carex contigua, Dactylis glomerata, Elsholtzia ciliata, Glechoma hederacea, Xantho­xalis stricta. Its communities, that occur in parks and gardens, were described in shaded habitats. The differences between this association and those of synanthropic vegetation close to it in the species composition are shown: ass. Leonuro–Arctietum tomentosi Lohmeyer in Tx. 1950 in Kursk Region and ass. Arctio tomentosi–Rumicetum obtusifolii Passarge 1959 in Slovakia (Table 5; Fig. 6, 7). Identified syntaxa, described within different orders and classes, have high floristic similarity because their communities are directed series with gradually changing conditions (the DCA-ordination diagram on Fig. 8). There is a change of impact of some ecological factors (light, moisture, reaction and richness in mineral nitrogen of soils and substrates) along axis 1. On this axis the communities of var. Glechoma hederacea of the ass. Arrhenathero elatioris–Dactylidetum glomeratae occupy an intermediate position and species, that have high constancy in ass. Glechomo hederaceae–Dactylidetum glomeratae, also occur in these. In all likelihood, the axis 2 is a change in degree of anthropogenic impact, which does not significantly influence on the syntaxon differentiation. The results of DCA-ordination are confirmed by the value ranges of ecological factors (Fig. 9).