Formalized classification of ephemeral wetland vegetation (Isoëto-Nanojuncetea class) in Poland (Central Europe)

Data set and classfication method

The 69,562 relevés stored in the Polish Vegetation Database (PVD) (Kącki & Śliwiński, 2012) were used for this study. Based on the literature and expert knowledge (Oberdorfer, 1977; Popiela, 1997; Matuszkiewicz, 2007; Kącki, Czarniecka & Swacha, 2013), we selected 63 diagnostic species for the Isoëto-Nanojuncetea class (Table 1). Then we defined groups of diagnostic species into class and alliances as reported from Central Europe (Matuszkiewicz, 2007; Mucina et al., 2016). Using groups of species, we created functional species groups based on the total cover of all species (#TC) separately for the class and alliances and functional species group with selection based on the highest cover of a single species (#SC) according to Landucci et al. (2015) approach. Sociological groups of species were simultaneously determined using the fidelity phi coefficient (Chytrý et al., 2002). We applied unequivocal classification in accordance with Cocktail method (Bruelheide, 1997). Formulas were created using the formal operators AND, OR, NOT available in Juice software (Tichý, 2002). The structure of the formulas for alliance level based on total cover groups #TC and cover of a single species #SC, while the association level was created by a combination of sociological species groups or a cover threshold of particular diagnostic species associated with the alliance`s total cover group, enabling us to keep the syntaxonomical hierarchy, which means that relevés classified to a particular association were also included into the appropriate alliance and the class (Landucci et al., 2020; Kącki et al., 2020). An Expert System was prepared and applied to classify the whole data set of PVD and 1,340 relevés were organized at the class level. Relevés without geographical coordinates and a surface area smaller than 1 m² or greater than 100 m² were excluded. We also removed cultivated plants from the analyses. Next, three relevés were randomly selected from each unit of grid square of 1.25 longitude × 0.75 latitude (ca. 1.5 × 1.4 km) from each vegetation units distinguished. Finally, we used data set of 903 relevés to prepare synthetic tables, distribution maps and descriptions of the syntaxa. For each syntaxon diagnosic, differential, constant and dominant species were determined and a combined synoptic table with percentage frequency and fidelity was created. Additionally, the statistical significance of the fidelity was calculated using Fisher’s exact test (Sokal & Rohlf, 1995; Chytrý et al., 2002). We considered as a diagnostic only species which were included in the list of preselected 63 species for Isoëto-Nanojunceta class, while the others we indicated as differential species. Species were considered as diagnostic or differential for the alliances at phi ≥ 0.20 and for the association at phi ≥ 0.25 and Fisher’s exact test at significance level of p < 0.001. Constant and dominant species were those with a frequency of ≥ 40% and with a cover value at least 25% in at least 5% of relevés of particular vegetation units, respectively. We used Euro-Med-Plant+ nomenclature for species names (access 11.2018). Taxonomically critical taxa were merged into aggregates.

Statistics, map preparation, nomeclature

Ecological gradients of defined associations were evaluated by Detrended Correspondence Analysis (DCA) using Juice 7.1.28 and ordination methods available in R for Windows with VEGAN module (Oksanen et al., 2011). For interpretation of the main environmental gradients, average non-weighted Ellenberg indicator values for light, temperature, continentality, soil reaction, moisture and nutrients (Ellenberg et al., 1992) were used as supplementary variables. Ellenberg indicator values were calculated for weighted relevés by species cover (CWM). The ordination (DCA) was conducted with data transformation b = (Xi,j)^p (p = 0.5) and scaling by 26 segments. Distribution maps of all associations were prepared using PostgreSQL 11.0 database with PostGIS 2.6 extension. Visualisation of the result was prepared on QGIS3.16.3 and results showed on digital elevation map with accuracy 100 × 100 m by pixel.

List of syntaxa and species composition

Eleocharition soloniensis Philippi 1968

Diagnostic species: Eleocharis acicularis, Cyperus fuscus, Limosella aquatica, Eleocharis ovata, Carex bohemica, Elatine hexandra, Elatine hydropiper, Riccia cavernosa, Elatine triandra

Differential species: Callitriche palustris s. l., Alisma plantago-aquatica, Rorippa palustris, Leersia oryzoides, Juncus articulatus, Alopecurus geniculatus, Ranunculus sceleratus, Juncus bulbosus, Physcomitrium eurystomum

Constant species: Cyperus fuscus, Limosella aquatica, Gnaphalium uliginosum, Eleocharis acicularis, Rorippa palustris

Dominant species: Cyperus fuscus, Eleocharis acicularis, Eleocharis ovata, Limosella aquatica, Elatine hexandra

In Poland, the Eleocharition soloniensis alliance comprises four plant communities (Appendix 2 and 3):

1. Polygono-Eleocharitetum ovatae Eggler 1933

2. Cypero fusci-Limoselletum aquaticae Oberd. ex Korneck, 1960

3. Cyperetum micheliani Horvatić, 1931

4. Community with Coleanthus subtilis

They develop on moderately fertile habitats, mainly on the drying-out bottom of fishponds, the margins of mid-field ponds, and periodically exposed banks of river channels, mostly in Poland’s western part. (Fig. 4). According to DCA analysis, based on the Ellenberg Indicator Values, moisture, nutrients, and temperature differ the vegetation of the Eleocharition alliance (Fig. 5).

Polygono-Eleocharitetum ovatae Eggler 1933

Diagnostic species: Eleocharis ovata, Carex bohemica, Elatine hexandra, Eleocharis acicularis, Elatine triandra, Lindernia procumbens

Differential species: Alisma plantago-aquatica, Juncus bulbosus, Physcomitrium eurystomum, Oenanthe aquatica, Scirpus radicans

Constant species: Eleocharis ovata, Eleocharis acicularis, Alisma plantago-aquatica,

Dominant species: Eleocharis ovata, Elatine hexandra, Eleocharis acicularis, Carex bohemica, Juncus bulbosus

Distribution: Polygono-Eleocharetum ovatae occurs on scattered sites in the south-western and south-eastern parts of Poland. It does not occur in the north of the country due to scarcity of typical habitat—the fishpond complexes (Fig. 4).

Physiognomical layout: The individual patches show a single-layer structure and form a low turf-like vegetation, with varying coverage. The association often develops patchy structure, with typical plots composed of diagnostic species dispersed between stands of Phragmito-Magnocaricetea and Bidentetea vegetation (Fig. 5).

Habitat requirements: The Polygono-Eleocharitetum ovatae is associated with ponds habitats (old facilities), with regular, extensive fishery management for a long time. It does not appear on natural water bodies across Poland. It is mostly found on a fine-grained, wet, moist or drying sandy-loamy or silty substrate, rich in mineral compounds. Within the Eleocharition alliance this association is usually the most waterlogged one habitat (Fig. 6).

Cypero fusci-Limoselletum aquaticae Oberd. ex Korneck, 1960

Diagnostic species: Cyperus fuscus, Limosella aquatica, Eleocharis acicularis

Differential species: Salix purpurea, Plagiochila asplenioides

Constant species: Cyperus fuscus, Limosella aquatica, Gnaphalium uliginosum, Plantago major subsp. intermedia, Juncus bufonius, Rorippa palustris, Rumex maritimus

Dominant species: Cyperus fuscus, Limosella aquatica, Plantago major subsp. intermedia, Eleocharis acicularis

Distribution: The Cypero fusci-Limoselletum aquaticae occurs mostly in the western part of Poland on natural sites along river valleys of Odra, Warta and lower part of Vistula while rarely is found on fishpond‘s complexes (Fig. 4).

Physiognomical layout: The association develops compact turf, usually at late summer. It is distinguished by the abundant occurrence of Cyperus fuscus (Fig. 5).

Habitat requirements: In Poland, patches of the Cypero fusci-Limoselletum aquaticae develop periodically on flooded habitats, located on gently sloping banks, coastal mudslides, margins of oxbow lakes and small water-filled hollows on the flooded terraces. They are also found on the freshly exposed bottom of water reservoirs, e.g. lakes, small mid-field depressions, at the bottoms of drained fishponds and dam reservoirs. This association has the highest requirements regarding nutrients and have less demand for moisture within the whole alliance’ communities (Fig. 6).

Cyperetum micheliani Horvatić, 1931

Diagnostic species: Cyperus michelianus

Constant species: Rumex maritimus, Plantago major subsp. intermedia, Gnaphalium uliginosum, Cyperus michelianus, Cyperus fuscus, Rorippa palustris, Oxybasis rubra, Cirsium arvense, Salix fragilis, Rorippa amphibia, Lythrum salicaria, Limosella aquatica, Erigeron canadensis, Bidens frondosus, Atriplex prostrata, Agrostis stolonifera

Dominant species: Cyperus michelianus, Cyperus fuscus

Distribution: The Cyperetum micheliani was found on single locality in south-western part of Poland, in the Odra river valley near Głogów (Fig. 4).

Physiognomical layout: The association develops compact turf and and is distinguished by the dominance of Cyperus michelianus (Fig. 5).

Habitat requirements: In Poland, patches of the Cyperetum micheliani develop on margins of oxbow lakes and on the flooded terraces of the riverbanks. The association has highest requirements regarding nutrients and has less demand for moisture within the Eleocharition alliance (Fig. 6).

Community with Coleanthus sublitis

Diagnostic species: Coleanthus subtilis, Veronica peregrina, Riccia cavernosa, Myosurus minimus, Limosella aquatica

Differential species: Ranunculus trichophyllus, Callitriche palustris s. l., Persicaria lapathifolia s. l.

Constant species: Coleanthus subtilis, Veronica peregrina, Myosurus minimus, Limosella aquatica, Persicaria lapathifolia s. l., Rorippa palustris, Callitriche palustris s. l., Persicaria hydropiper, Juncus bufonius, Riccia cavernosa, Ranunculus trichophyllus

Dominant species: Coleanthus subtilis, Veronica peregrina, Myosurus minimus, Riccia cavernosa, Persicaria lapathifolia s. l., Limosella aquatica, Callitriche palustris s. l., Ranunculus trichophyllus

Distribution: So far, the community was found only in the south-western part of Poland, in fishpond complexes in Lower Silesia (Fig. 4).

Physiognomical layout: The community is well distinguished by the dominance of short grasses mostly the diagnostic species Coleanthus subtilis (Fig. 5).

Habitat requirements: Preferably, plots of is this community develop in ponds used in annual or biennial cycle (stocking ponds). So far, this plant communities developing in autumn or during seasonal summer water deficit have been recorded much less frequently.

Verbenion supinae Slavnić 1951

Diagnostic species: Pulicaria vulgaris, Cyperus flavescens, Elatine alsinastrum, Schoenoplectus supinus, Lythrum hyssopifolia

Differential species: Agrostis stolonifera, Alisma lanceolatum, Atriplex prostrata, Argentina anserina, Xanthium orientale subsp. italicum, Inula britannica, Cynosurus cristatus, Salix triandra, Poa pratensis

Constant species: Agrostis stolonifera, Plantago major subsp. intermedia

Dominant species: Pulicaria vulgaris, Elatine alsinastrum, Schoenoplectus supinus, Juncus bufonius, Cyperus flavescens, Plantago major subsp. intermedia, Alisma lanceolatum

According to the formal classification of our data set, the Verbenion supinae alliance includes four associations (Appendix 2 and 3):

1. Veronico anagalloidis-Lythretum hyssopifoliae Wagner ex Holzner 1973

2. Cyperetum flavescentis Koch, 1926

3. Pulicario vulgaris-Menthetum pulegii Slavnić 1951

4. Eleocharito-Schoenoplectetum supini Soo & Ubrizsy, 1948 (orig. Schoenoplectus supinus-Heleocharis acicularis assz.)

In Poland, vegetation of this alliance occurs rarely, mainly in the big river valleys and in the Lublin Upland (Fig. 3). According to DCA analysis based on the Ellenberg Indicator Values, Poland’s Verbenion supinae alliance has high demand of the temperature and nutrient content (Fig. 7).

Veronico anagalloidis-Lythretum hyssopifoliae Wagner ex Holzner 1973

Diagnostic species: Juncus ranarius

Constant species: Juncus ranarius, Oxybasis rubra, Oxybasis glauca, Juncus compressus, Atriplex prostrata, Argentina anserina, Agrostis stolonifera

Dominant species: Juncus ranarius, Carex secalina, Bolboschoenus maritimus agg.

Distribution: There are only three known sites of the Veronico anagalloidis-Lythretum hyssopifoliae in Poland located in the lowland belt of Wielkopolska, Kujawy and Mazury regions (Fig. 8).

Physiognomical layout: The association is well defined by Juncus ranarius and the presence of halophilous species.

Habitat requirements: The association occurs on saline, moist silts, and wet soils in nutrient rich habitats.

Cyperetum flavescentis Koch, 1926

Diagnostic species: Cyperus flavescens, Sagina nodosa

Differential species: Calliergonella cuspidata, Triglochin palustris, Ranunculus flammula

Constant species: Cyperus flavescens, Sagina nodosa, Ranunculus flammula, Juncus articulatus, Calliergonella cuspidata, Agrostis stolonifera

Dominant species: Cyperus flavescens

Distribution: The Cyperetum flavescentis is distributed in the south-eastern part of Poland (Fig. 8).

Physiognomical layout: It forms very low and sparsy turfs on a sandy or sandy-loam substrates with weak acidity. The plant communities are usually clearly dominated by Cyperus flavescens (Fig. 9).

Habitat requirements: The communities develop periodically on flooded and grazed lakesides as well as peaty hollows. According to DCA analysis Cyperetum flavescentis requires lower humidity and nutrients content than other associations of the Verbenion alliance (Fig. 7).

Pulicario vulgaris-Menthetum pulegii Slavnić 1951

Diagnostic species: Pulicaria vulgaris

Differential species: Xanthium orientale subsp. italicum, Inula britannica, Lysimachia nummularia, Matricaria discoidea, Poa pratensis, Cynosurus cristatus, Agrostis stolonifera

Constant species: Pulicaria vulgaris, Agrostis stolonifera, Plantago major subsp. intermedia, Persicaria hydropiper, Juncus bufonius, Gnaphalium uliginosum, Persicaria lapathifolia s. l., Rumex maritimus, Argentina anserina, Bidens tripartitus

Dominant species: Pulicaria vulgaris, Juncus bufonius, Plantago major subsp. intermedia, Eleocharis acicularis, Mentha pulegium, Lysimachia nummularia

Distribution: In Poland, the association occurs on scattered sites, mainly in the valleys of Odra and Warta rivers (Fig. 8).

Physiognomical layout: It is a community found mostly in the flood zone of big rivers. In addition to the dominating diagnostic species, an essential contribution to this vegetation are species from the Bidentetea class.

Habitat requirements: The association reveals relatively high nutrients demand (Fig. 7).

Eleocharito-Schoenoplectetum supini Soo & Ubrizsy, 1948 nomina inversa prop. (orig. Schoenoplectus supinus - Heleocharis acicularis assz.)

Diagnostic species: Elatine alsinastrum, Schoenoplectus supinus, Lythrum hyssopifolia

Differential species: Alisma lanceolatum, Persicaria amphibia

Constant species: Alisma lanceolatum, Elatine alsinastrum, Schoenoplectus supinus, Limosella aquatica

Dominant species: Elatine alsinastrum, Schoenoplectus supinus, Alisma lanceolatum, Plantago major subsp. intermedia, Lythrum portula, Juncus bufonius

Distribution: Eleocharito-Schoenoplectetum supini is scattered in Poland. The majority of records come from the Lublin region’s uplands, but it was also sporadically found in northwestern Poland (Fig. 8).

Physiognomical layout: In the initial phase, it is a distinguished pioneer vegetation type and was encountered in both the terrestrial and aquatic habitats. Its optimal phase is characterized by a high cover and relatively height (up to half a meter) (Fig. 9).

Habitat requirements: The association develops most often in temporary pools in arable field depression (some of them occur episodically during periods with abundant precipitation). The association is the most demanding considering moisture and temperature within the Verbenion supinae alliance (Fig. 7).

Radiolion linoidis Pietsch, 1973

Diagnostic species: Hypericum humifusum, Radiola linoides, Gypsophila muralis, Anagallis minima, Anthoceros punctatus s. l., Spergularia rubra, Juncus capitatus, Illecebrum verticillatum, Phaeoceros laevis, Gnaphalium uliginosum, Riccia glauca, Isolepis setacea, Riccia sorocarpa, Fossombronia wondraczekii, Montia arvensis

Differential species: Spergula arvensis, Rumex acetosella, Scleranthus annuus, Equisetum arvense, Sagina procumbens, Setaria pumila, Elytrigia repens, Viola arvensis, Fallopia convolvulus, Polygonum aviculare s. l., Mentha arvensis, Stellaria media s. l., Veronica arvensis, Juncus bufonius, Achillea millefolium, Veronica serpyllifolia, Erigeron canadensis, Anthemis arvensis, Raphanus raphanistrum, Anagallis arvensis, Myosotis arvensis, Cyanus segetum, Cerastium fontanum subsp. vulgare, Cirsium arvense, Apera spica-venti, Teesdalia nudicaulis, Stachys palustris, Vicia sativa s. l., Oxalis fontana, Arnoseris minima, Vicia hirsuta, Convolvulus arvensis, Galeopsis tetrahit s. l., Capsella bursa-pastoris, Holcus mollis, Ceratodon purpureus, Erodium cicutarium, Digitaria ischaemum, Agrostis capillaris, Bryum argenteum, Setaria viridis, Vicia tetrasperma, Veronica persica, Ranunculus repens, Pohlia nutans, Sonchus arvensis

Constant species: Juncus bufonius, Gnaphalium uliginosum, Rumex acetosella, Polygonum aviculare s. l., Plantago major subsp. intermedia, Sagina procumbens, Hypericum humifusum, Radiola linoides, Gypsophila muralis, Spergula arvensis, Anagallis minima, Spergularia rubra, Scleranthus annuus, Equisetum arvense

Dominant species: Juncus bufonius, Isolepis setacea

There are six associations of the Radiolion linoidis in Poland distinguished by a formal classification (Appendix 2 and 3):

1. Stellario uliginosae-Isolepidetum setaceae Libbert, 1932

2. Centunculo minimi-Anthoceretum punctati Koch ex Libbert, 1932

3. Hyperico humifusi-Spergularietum rubrae Wójcik, 1968

4. Panico-Illecebretum verticillati Diemont et al., 1940

5. Cerastio dubii-Ranunculetum sardoi Oberdorfer ex Vicherek

6. Community with Montia arvensis

According to DCA analysis based on the Ellenberg Indicator Values, the Radiolion linoidis alliance communities are differentiated by habitat requirements in terms of moisture, light, nutrients, and soil reaction.

Stellario uliginosae-Isolepidetum setaceae Libbert, 1932

Diagnostic species: Isolepis setacea

Differential species: Stellaria alsine, Juncus articulatus, Leontodon saxatilis, Calamagrostis epigejos, Juncus effusus, Carex flava agg.

Constant species: Isolepis setacea, Juncus articulatus, Juncus bufonius, Gnaphalium uliginosum, Stellaria alsine, Sagina procumbens, Plantago major subsp. intermedia

Dominant species: Isolepis setacea, Juncus bufonius

Distribution: Stellario uliginosae-Isolepidetum setaceae rarely occurs in Poland, mostly in the river valleys in its western part (Fig. 10).

Physiognomical layout: It occurs in the form of low turf with varying degrees of vegetation cover. The communities have a considerable number of diagnostic species of the Molinio-Arrhenatheretea and the Scheuchzerio-Caricetea vegetation (Fig. 11).

Habitat requirements: This plant community was recorded on extensively used forest roads, as well as mid-field depressions and pond margins. According to DCA results, Stellario uliginosae-Isolepidetum setaceae has higher demand of moisture and lower soils reaction requirements than other communities of the Radiolion alliance (Fig. 12).

Centunculo minimi-Anthoceretum punctati Koch ex Libbert, 1932

Diagnostic species: Anagallis minima, Anthoceros punctatus s. l., Radiola linoides, Juncus capitatus, Phaeoceros laevis,

Differential species: Rumex acetosella

Constant species: Anagallis minima, Juncus bufonius, Radiola linoides, Gnaphalium uliginosum, Anthoceros punctatus s. l., Polygonum aviculare s. l., Sagina procumbens, Plantago major subsp. intermedia, Juncus capitatus, Rumex acetosella, Gypsophila muralis, Equisetum arvense, Spergula arvensis, Hypericum humifusum

Dominant species: Juncus bufonius, Anthoceros punctatus s. l. l.

Distribution: The Centunculo minimi-Anthoceretum punctati occurs mostly in the south-eastern part of the country: the Masovian Plain, the Małopolska Upland, the Podlasie Lowland and the Beskid Foothills. Additionally, a single site was noted in the western Poland—Fig. 10.

Physiognomical layout: The communities are characterized by small annual vascular plants and significant share of bryophytes (Fig. 11).

Habitat requirements: The community develops on arable fields, in the second half of summer and early autumn. A necessary condition for its development is the presence of an exposed and moist substrate. In such places, rainwater stays longer, and there are no dense high weeds stands. These are furrows and mid-field depressions, drying edges of puddle margins, wet spots on clay or sandy, slightly acidic soil. This association has lower moisture and higher temperature demand within the Radiolion alliance (Fig. 12).

Hyperico humifusi-Spergularietum rubrae Wójcik, 1968

Diagnostic species: Spergularia rubra, Gypsophila muralis, Hypericum humifusum, Anagallis minima, Anthoceros punctatus s. l., Laphangium luteoalbum,

Differential species: Scleranthus annuus, Convolvulus arvensis, Veronica serpyllifolia, Anthemis arvensis, Rumex acetosella, Elytrigia repens, Sagina procumbens, Oxalis fontana, Anagallis arvensis, Setaria pumila, Polygonum aviculare s. l., Myosotis arvensis, Raphanus raphanistrum, Erigeron canadensis, Viola arvensis, Crepis tectorum, Spergula arvensis

Constant species: Spergularia rubra, Gypsophila muralis, Juncus bufonius, Gnaphalium uliginosum, Sagina procumbens, Polygonum aviculare s. l., Scleranthus annuus, Plantago major subsp. intermedia, Rumex acetosella, Hypericum humifusum, Anagallis minima, Elytrigia repens, Veronica serpyllifolia, Setaria pumila, Erigeron canadensis, Spergula arvensis, Anthemis arvensis, Equisetum arvense, Viola arvensis

Dominant species: Juncus bufonius, Rumex acetosella

Distribution: The Hyperico humifusi-Spergularietum rubrae occurs in the south-eastern part of Poland (Fig. 10).

Physiognomical layout: The association dominated by small annual vascular plants, mostly diagnostic for Radiolion alliance with considerable constancy and also has species diagnostic for Papaveretea vegetation (Fig. 11).

Habitat requirements: The Hyperico humifusi-Spergularietum rubrae occurs in conditions very similar to Centunculo minimi-Anthocetetum punctati and it is found in wet depression in arable fields and in vicinity of mid-field water reservoirs. Likewise, DCA analysis results showed similarity in habitat demand as Centunculo minimi-Anthoceretum punctati (Fig. 12).

Panico-Illecebretum verticillati Diemont et al., 1940

Diagnostic species: Illecebrum verticillatum, Spergularia rubra, Hypericum humifusum, Radiola linoides

Differential species: Teesdalia nudicaulis, Arnoseris minima, Spergula arvensis, Scleranthus annuus, Holcus mollis, Rumex acetosella, Digitaria ischaemum, Raphanus raphanistrum, Setaria pumila, Fallopia convolvulus, Aphanes microcarpa, Anthoxanthum aristatum, Galeopsis tetrahit s. l., Rhinanthus angustifolius, Bidens tripartitus, Setaria viridis, Stachys palustris, Persicaria hydropiper, Mentha arvensis, Viola tricolor agg., Myosotis arvensis, Achillea millefolium

Constant species: Illecebrum verticillatum, Spergula arvensis, Rumex acetosella, Juncus bufonius, Spergularia rubra, Scleranthus annuus, Persicaria hydropiper, Hypericum humifusum, Gnaphalium uliginosum, Radiola linoides, Mentha arvensis, Setaria pumila, Teesdalia nudicaulis, Bidens tripartitus, Arnoseris minima, Polygonum aviculare s. l., Equisetum arvense, Fallopia convolvulus, Raphanus raphanistrum, Agrostis stolonifera

Dominant species: Illecebrum verticillatum

Distribution: Panico-Illecebretum verticillati occurs in the south-eastern part of Poland (Fig. 10) similarly to Centunculo minimi-Anthocetetum punctati and Hyperico humifusi-Spergularietum rubrae.

Physiognomical layout: It develops at the end of summer, in the form of small patches, on moist soil in crop stands or on stubble. Compared to Centunculo-Anthoceretum, it differs in its abundant occurrence of Illecebrum verticillatum and Spergula arvensis and others sandy, acidophilous plants with the negligible amount of bryophytes.

Habitat requirements: The soil is more acidic; according to DCA, it also has lower humidity and higher temperature requirements (Fig. 12).

Cerastio dubii-Ranunculetum sardoi Oberdorfer ex Vicherek 1968

Diagnostic species: Ranunculus sardous, Myosurus minimus, Plantago major subsp. intermedia

Differential species: Capsella bursa-pastoris, Bryum dichotomum, Bryum caespiticium, Bryum ruderale, Papaver rhoeas, Linaria spartea, Galium aparine, Dicranella varia, Thlaspi arvense, Veronica persica, Barbula unguiculata, Veronica hederifolia, Erodium cicutarium, Valerianella locusta, Tortula modica, Phascum cuspidatum, Brachythecium rutabulum, Geranium pusillum, Ceratodon purpureus, Stellaria media s. l., Marchantia polymorpha, Leptobryum pyriforme, Vicia hirsuta, Tripleurospermum inodorum agg.

Constant species: Ranunculus sardous, Plantago major subsp. intermedia, Myosurus minimus, Juncus bufonius, Gnaphalium uliginosum, Capsella bursa-pastoris, Stellaria media s. l., Ceratodon purpureus, Bryum dichotomum, Bryum caespiticium, Tripleurospermum inodorum agg., Dicranella varia, Bryum ruderale, Viola arvensis, Vicia hirsuta, Veronica persica, Thlaspi arvense, Sagina procumbens, Riccia glauca, Polygonum aviculare s. l., Mentha arvensis, Leptobryum pyriforme, Galium aparine, Erodium cicutarium, Bryum argenteum, Brachythecium rutabulum

Dominant species: Ranunculus sardous, Myosurus minimus, Riccia glauca, Lythrum portula, Juncus bufonius, Gnaphalium uliginosum

Distribution: The association found on scattered localities mainly in river valleys across Poland (Fig. 10).

Physiognomical layout: The patches of the association develop in early summer—mainly in June and July. The number of species from the Isoëto-Nanojuncetea class is insignificant, and plants of the Papaveretea class are considerable contributors (Fig. 11).

Habitat requirements: It occurs in damp places in mid-field furrows, on fallow fields and their margins. It is a short-term seasonal community, composed exclusively of annuals. Analysis of Ellenberg indicator values showed that Cerastio dubii-Ranunculetum sardoi has a higher demand for moisture and nutrient content (Fig. 12).

Community with Montia arvensis

Diagnostic species: Montia arvensis, Myosurus minimus, Riccia sorocarpa

Differential species: Dicranella staphylina, Holcus lanatus, Epilobium ciliatum, Lotus pedunculatus, Bryum subapiculatum, Lathyrus pratensis, Bryum violaceum, Lysimachia vulgaris, Myosotis discolor, Pohlia annotina, Poa trivialis, Arabidopsis thaliana, Cerastium glomeratum, Eupatorium cannabinum, Vicia hirsuta, Solidago gigantea, Rumex crispus, Lamium purpureum, Bidens frondosus, Veronica arvensis, Ranunculus repens, Stellaria palustris, Pleuridium acuminatum, Glyceria declinata, Galium palustre agg., Tripleurospermum inodorum agg., Leptobryum pyriforme, Ceratodon purpureus

Constant species: Montia arvensis, Juncus bufonius, Myosurus minimus, Lotus pedunculatus, Holcus lanatus, Vicia hirsuta, Tripleurospermum inodorum agg., Ranunculus repens, Gnaphalium uliginosum, Epilobium ciliatum, Dicranella staphylina, Bidens frondosus, Agrostis stolonifera, Veronica arvensis, Rorippa palustris, Persicaria hydropiper, Lysimachia vulgaris, Polygonum aviculare s. l., Poa trivialis, Plantago major subsp. intermedia, Persicaria lapathifolia s. l., Mentha arvensis, Ceratodon purpureus, Bryum subapiculatum

Dominant species: Montia arvensis, Juncus bufonius, Pohlia annotina, Argentina anserina

Distribution: This community was recorded in western Poland in the Lubuskie Region only (Fig. 10).

Physiognomical layout: Montia arvensis is mostly accompanied by Myosurus minimus and common segetal weeds of the Papaveretea class (Fig. 11).

Habitat requirements: Community with Montia arvensis was found in moist, sandy arable fields. It develops mostly near backwaters after spring thaws, on silts, in drainage ditches and spring outflows. Less frequently it was found in fallows and wastelands. According to DCA, the association showed relatively high soil reaction and moisture (Fig. 12).