Vegetation with Aira Praecox in the Czech Republic Compared to Its

Phytocoenologia 37 (1) 115Ð134 BerlinÐStuttgart, March 22, 2007

Vegetation with Aira praecox in the Czech Republic compared to its variability in Western Europe by Toma´sˇ Cˇ erny´, Petr Petrˇ ı´k, Karel Boublı´k and Jirˇ´ı Kolbek, Pru˚ honice with 2 figures and 3 tables

Abstract. New phytosociological material of xero- and psammophytic vegetation dominated by the annual grass Aira praecox is presented for the Czech Republic. Such vegetation type has not been yet published in the Czech Republic, however Airetum praecocis has already been reported in the national checklists. For the correct syntaxonomical evaluation, the relevant data dealing with similar vegetation from the centre of its distribution range in north-western Europe were selected. In the Czech Republic, only the Aire- tum praecocis and the Vulpietum myuri can be distinguished. Within the Airetum praecocis, two subassociations (typicum and plantaginetosum lanceolatae) are distinguished, differing by their successional age. The Vulpietum myuri is broadly distributed in the Czech Republic representing only a marginal vegetation type with populations of Aira praecox. Based on the European review, six associations were distinguished within alliances Corynephorion canescentis, Thero-Airion and Armer- ion elongatae. The structure, composition, ecology, and distribution of these associations are discussed. Successional age of sand swards and soil mineral content are the main ecological gradients responsible for the vegetation variability. The Airetum praecocis prefers the centre of these environmental gradients. Its floristic composition is poor on the proportion of psammophytes, conversely, it shares common meadow species.

Keywords: Central and Northwestern Europe, classification, distribution, dry grasslands, phytosociology, sandy soils, Thero-Airion.

Introduction Dry grasslands on sandy soils are nowadays among strongly threatened and retreating plant communities in the Czech Republic (Moravec et al. 1995). The retreat of this type has been caused by the cessation of permanent moderate disturbances by grazing animals and miscellaneous human activities (e.g. eutrophication, afforestations, see Jentsch & Beyschlag 2003). On the other hand, new habitats suitable for the development of psammophytes arise in newly opened sand-pits, around quarries, in heavily disturbed military training areas (cf. Täuber 1994, Romahn 1998, Renn- wald 2000), and also on extensively used forest roads. Apart from the establishment of such secondary habitats, a common opinion prevails that sand ecosystems suffer mainly by fragmentation and species extinctions

DOI: 10.1127/0340-269X/2007/0037-0115 0340-269X/07/0037-0115 $ 5.00 ” 2007 Gebrüder Borntraeger, D-14129 Berlin · D-70176 Stuttgart 116 T. Cˇ erny´ et al. connected with resulting diaspore limitations (Jentsch & Beyschlag 2003, Eichberg et al. 2006). In the Czech Republic, the psammophytic communities are concentrated in areas with deposits of fluvial and eolian sands, or redeposited eroded material from sandstones (Doksy and Trˇebonˇ regions in Southern and Northern Bohemia, respectively, Labe River Basin). Scattered occurrences were recorded in Western Bohemia. The vegetation of these regions is com- posed of suboceanic floroelement, while southern Moravian fluvial and eolian sands are differentiated by a spectrum of Pannonian species (Skalicky´ 1988). Aira praecox represents suboceanic species (Meusel et al. 1965), strongly dependent upon the weather; its development is enhanced by mild winter followed by rainy spring months. On the other hand, frosty winters suc- ceeded by dry springs suppress its germinating and growth (Krausch 1968, Jeckel 1984, Coomes et al. 2002). Seeds of A. praecox persist in the soil from the early successional stages to mid-successional ones, which is typical for pioneers with broader amplitude (Eichberg et al. 2006). In the Atlantic climate, Newman (1967) described the reduction of Aira-seeds produced by delayed date of germination (it is characterised as winter-annual), a fea- ture that has not been observed in the Czech Republic. It is a typical calci- fuge plant (Paul 1975) growing mainly on slightly to strongly acidic and slightly humose primitive sand soils. Aira praecox is typically considered to be the characteristic species of the class Koelerio-Corynephoretea Klika in Klika & Nova´k 1941 (e.g. Weeda et al. 1996). A relatively high number of units dominated by Aira praecox were described in Western Europe in the past (Hülbusch 1974), however their status seems to be uncertain. This vegetation is broadly distributed in Western and North-Western Europe on glacifluvial sands, mo- raine gravel banks and eolic sand dunes. Furthermore, A. praecox rarely grows in disturbed salt grasslands in coastal regions (Saginion mariti- mae Westhoff et al. 1962) and in acidophilous heather vegetation in inland areas (Genistion pilosae Böcher 1943, see Berg et al. 2004). The composition of the xerophilous psammophytic vegetation in the Czech Republic is known only from a small collection of phytosociological material (several tens of releve´s from the class Koelerio-Corynephore- tea in the Czech National Phytosociological Database, cf. Chytry´ & Ra- fajova´ 2003). Only one paper deals with the vegetation of shallow sandy soils in more detail (Toman 1988), so there is a lack of any synthesis on this vegetation from the Czech Republic. Aira praecox is a rare species in the Czech Republic, where it reaches the south-eastern limit of its distribution area (Fig. 1). The spring ephemeral grass vegetation has been traditionally reported from Bohemia (Kolbek & Vicherek 1995,Sa´ dlo & Chytry´ 2001), but published phytosociological material is nearly absent from the literature. Several releve´s are dispersed in floristic reports and in one paper (Korneck 1974). Therefore, both the composition of the two following associations occurring in the Czech Re- public (Filagini-Vulpietum Oberdorfer 1957 and Airetum praecocis Vegetation with Aira praecox 117

Fig. 1. Present distribution (full circles) and extinct occurrences (empty circles) of Aira praecox in the Czech Republic.

Krausch 1967, cf. Kolbek & Vicherek 1995) and their relation to other syntaxa remains unknown. The above-described situation has lead us to the decision to gather new phytosociological data on this threatened vegetation type and carry out a comparative synthesis with respect to similar European data. We want to answer (1) whether it is possible to clearly distinguish the association Aire- tum praecocis both at regional (Czech Republic) and broader (W Eu- rope) scales and (2) what is the floristic composition of Aira praecox-rich vegetation in its eastern distribution limit.

Materials and methods In 2002 and 2003, we collected 57 releve´s with Aira praecox within the Czech Republic, using the method of the Zürich-Montpellier school (Westhoff & van der Maarel 1973). In the field, samples with A. praecox were located with the aim to describe the whole variability at the localities studied. For the Czech Republic, a data set comprising both our and other unpublished releve´s with the presence of A. praecox was compiled. For vegetation classification, the comparative releve´ material from the Western- European range (Germany and France) was collected, all of it recorded by the authors according to Braun-Blanquet’s approach. For other countries, only synthetic tables were available, thus we could not use them for analysis. First, the releve´s classified in the original papers as the Airetum praecocis were selected; second, the presence of A. praecox in combination with diagnostic species of Thero-Airion or Koelerio-Corynephore- 118 T. Cˇ erny´ et al. tea was used as another criterion for selection. The units with a high presence of A. praecox but with only local presence in westernmost Europe (e.g. Festuco tenuifoliae-Sedetum anglici Clement & Touffet 1977 distinguished in Bretagne) were excluded. The basic set consisted of 293 releve´s, including material from the Czech Republic. Due to the great number of releve´s used in this synthesis, a preliminary classification of this dataset was calculated using diagnostic species combinations published in the survey of the Dutch vegetation (Weeda et al. 1996). The fidelity of species was calculated using the phi-coefficient in the JUICE software (Ti- chy´ 2002) in distinguished vegetation units. The phi-coefficient is used if units of unequal sizes are to be compared (Chytry´ et al. 2002). The phi- coefficient describes the correlation between two categorial factors in a 2 by 2 contingency table (Sokal & Rohlf 1995). Indicator values (Ellenberg et al. 2001) indirectly characterising environmental conditions of the distinguished European units were computed for all releve´s in the JUICE software. The name ‘soil calcium’ was used instead of soil reaction since there is a stronger correlation of the indicator value with calcium content than with soil reaction (Schaffers & Sy´kora 2000). The nomenclature follows Flora Europaea (Tutin et al. 1964Ð1980) for vascular plant taxa and Kucˇ era & Va´ nˇ a (2003) and Veˇzda & Lisˇka (1999) for cryptogams. The names for syntaxa were taken from the above men- tioned Dutch vegetation survey (Weeda et al. 1996), with modifications according to the International Code of Phytosociological Nomenclature (Weber et al. 2000). Otherwise, the names are listed with the authors’ ab- breviations. The nomenclature of soils was adapted after Neˇmecˇ ek et al. (1990). The distribution map of A. praecox was prepared using the DMAP distribution software (Morton 2001).

Results The limited variability of vegetation with A. praecox in Table 1 is due to the fact that in Bohemia it reaches the eastern limit of its distribution. We distinguish two associations with Aira praecox (Airetum praecocis and Vulpietum myuri) based on our collected material. Regarding the various disturbance regimes and successional stages we divide the Airetum praecocis into two subassociations (see Table 1). 1. The association Airetum praecocis was described by Krausch (1967) with 10 releve´s but without the selection of a nomenclature type. We follow the typification of Dengler et al. (2003), who selected the lecto- typus of this association (Krausch 1967, Table 8, releve´ 2) and which is in accordance with our delimitation. 1a. The Airetum praecocis typicum subass. nova hoc loco (the nomenclature type is identical with the nomenclature type of the association name, see above) indicates the initial stages of open psammophilous vegetation in the Czech Republic. This community is differentiated by Spergula morisonii, Cerastium semidecandrum, Poa annua, and seedlings of Pinus Vegetation with Aira praecox 119

Table 1. Vegetation with Aira praecox in the Czech Republic. Rels 1Ð23: Airetum praecocis typicum; Rels 24Ð51: Airetum praecocis plantaginetosum lanceolatae; Rels 52Ð56: Vulpietum myuri. 120 T. Cˇ erny´ et al.

Table 1. (cont.)

sylvestris (Table 1, rels 1Ð23). Species demanding higher content of humus are absent. Since Aira praecox is sensitive to drought (Coomes et al. 2002), Aira-dominated stands can survive on slightly shadowed sites (e.g. gaps in pine forests, forest borders). Pine forests with sparse herb layer, stands of spring therophytes, and sand beaches without vegetation are the most frequent contact habitats. 1b. The Airetum praecocis plantaginetosum lanceolatae subass. nova hoc loco (nomenclature type: Krausch 1967, Table 8, releve´ 5) repre- Vegetation with Aira praecox 121 sents successionally more developed stands on stabilized sand (Table 1, rels 24Ð51). In the Czech Republic, the subassociation is characterised by pene- trating grassland species (Luzula campestris, Hypochoeris radicata, Anthox- anthum odoratum, Plantago lanceolata, Achillea millefolium agg., Festuca ovina, and F. tenuifolia) and by a well-developed moss layer (Polytrichum piliferum and Hypnum cupressiforme are considered as differential species). Acidophilous grasslands of shallow soils (Festuca tenuifolia- and F. ovina- dominated swards), heaths, open sand grasslands with Corynephorus canescens, acidophilous fringes, semi-ruderal vegetation with sparse cover, tram- pled vegetation, birch thickets, and pine plantations are the contact habitats of this subunit in the Czech Republic. Both subassociations geographically overlap in the Czech Republic. The important site controlling factors such as disturbance regimes, contact vegetation, physical soil structure, and microclimatic conditions seem to be responsible for the development of the respective subassociation. With an optimal development of environmental factors, the population density of A. praecox can reach ca. 200 individuals per 100 cm2 so they may form compact ground strata with sizes of up to tens of square metres. The vegetation prefers substrata compressed by trampling that are partly shadowed by trees. Therefore, we consider tent summer camps inside pine woodlands on sand around the Ma´chovo jezero reservoir (N Bohemia) as the most favourable habitats for the survival of A. praecox. Very strong populations develop on places where tents were built in past season. 2. The Vulpietum myuri is the species-poorest vegetation unit in Ta- ble 1, rather negatively differentiated against the previous ones, with the high dominance of Vulpia myuros and with transgressive differential species Cerastium semidecandrum, Arenaria serpyllifolia, and Myosotis stricta. It is spread fragmentarily along heavily disturbed open sites. We found no variability in this unit in our material.

Discussion

Syntaxonomy and synecology in Western and Central Europe The vegetation with A. praecox is not uniform, as this species covers a broader ecological spectrum within the Koelerio-Corynephoretea class. The classification of the majority of releve´s astheAiretum praecocis frequently covers several higher vegetation syntaxa. The high dominance of this grass is sometimes cited as the only reason for classifying the stands as the Airetum praecocis. In Table 2 in reference dataset, we distinguish six associations within three alliances (the Corynephorion canescentis, the Thero-Airion, and the Armerion elongatae Pötsch 1962). Within the reference dataset, several Czech releve´s were distributed across vegetation units contrary to their classification in results. This fact is caused both by the prevailing western European releve´s in comparative European material and by low Table 2. Synoptic table with percentage values of distinguished units, summary of 293 releve´s (France, Germany, Czech Republic). 1 Ð Corniculario aculeatae-Corynephoretum canescentis, 2 Ð Ornithopodo perpusilli-Corynephoretum canescentis, 3 Ð Airetum praecocis, 4 Ð Festuco ovinae-Thymetum serpylli, 5 Ð Festuco capillatae-Galietum maritimi, 6 Ð Vulpietum myuri. Percentage values with phi-coefficient Ն 20 are in bold. Asterisk (*) marks subspecies. Constancy values for non-vascular species could slightly vary since in 15 releve´s this layer was not identified. Vegetation with Aira praecox 123

Table 2. (cont.) 124 T. Cˇ erny´ et al.

Table 2. (cont.)

species richness of that Czech releve´s. Therefore, we did not accept strictly the European approach for the Czech syntaxonomy (see Tables 1 and 2). The distinguished communities differ in their dominants, successional age, and environmental conditions (Table 3, Fig. 2). Vegetation with Aira praecox 125

Table 3: Relative comparison of environmental conditions of the distinguished associations as reviewed from published sources. Symbols Ð, 0, +, ++ denote avoidance, indiffe- rent demands, weak affinity, or strong affinity to listed ecological factor, respectively.

The Airetum praecocis (Table 2, col. 3) is negatively characterised by the absence of any differential species. In contrast to the Western European material, Corynephorus canescens is usually absent from the Czech releve´s. Nevertheless, this grass occurs in the vicinity of the plots studied. We did not study in more detail reasons of this phenomenon. The Airetum praecocis occurs on slightly humose and fairly shallow Arenosols, rarely also on lithic Leptosols on solid bedrock (Korneck 1974), or on gravel ground (Wattez 1978, Wolfram 1996). The soils are poor in nutrients, soil reaction is acid to slightly acid and soil buffer capacity is very low. The soil humus content fluctuates around 6% (Newman 1967, Guittet & Paul 1974,Paul1975, Wattez 1978, Jeckel 1984, Heinken 1990, Romahn 1998). The spectrum of habitats consists of various sandy bare dunes in subatlantic areas, pine forests, ridges of forest roads or balks, where the plant succession is inhibited by mild disturbances (Krausch 1968, Jeckel 1984, Heinken 1990). The disturbances driven by ants and rabbits were proven to be a crucial mechanism supporting the constant regeneration of pioneer dry Corynephorus canescens-dominated stands (Jentsch et al. 2002). Under these conditions, the overall species richness is maintained by rich regeneration of plants through seeds. The regeneration is especially successful when disturbed patches are distributed within the reach of a dispersal distance of accompanying species (Jentsch et al. 2002). Similar small-scaled anthropogenic disturbances are a very probable cause of high densities of Aira praecox in the tent summer camps (see our results). The geographical centre of variability of the Airetum praecocis lies in north-western German lowlands with south-eastern projections in Bavaria, Lusatia, western Poland, and Bohemia (Arndt 1956, Zielonkowski 1973, Balcerkiewicz & Brzeg 1978, Wittig & Pott 1978, Otto et al. 1993, Frey 1994, Matuszkiewicz 2001). It occurs in other neighbouring Atlantic 126 T. Cˇ erny´ et al.

Fig. 2. Indicator values in box-plot diagrams for the units in Table 2. L Ð light; K Ð continentality; T Ð temperature; F Ð soil moisture; R Ð soil calcium; N Ð soil nutrients (productivity). Small circles indicate medians, boxes interquartile ranges, whiskers non- outlier ranges. Boxes with the same letter are statistically different at P < 0.05 (post hoc comparison by Tukey honest significant difference test for unequal size Ð Spjotvoll/Sto- line test). Vegetation with Aira praecox 127 countries too (e.g. Lawesson 2004). The Airetum praecocis can be characterised by “shifting strategy” in the landscape according to annual oscillation of weather and disturbance regimes. Such performance has been sometimes observed on permanent plots (Zielonkowski 1973, Täuber 1994, Coomes et al. 2002). Wolfram (1996) has noted the fact of small- scaled spatial mosaic of vegetation belonging to both the Thero-Airion and Corynephorion alliances, where Aira praecox-dominated stands occupy especially consolidated ground (e.g. by trampling). This was not observed in Bohemia, since large habitats with dry sandy vegetation are not developed here, where such mosaics could arise. But if such large spatial extent occurs, vegetation of the Thero-Airion can reach high species densities (up to 34 species per square meter, as observed by Romahn 1998). The Vulpietum myuri Philippi 1973 (Table 2, col. 6) is characterised by high abundance of Vulpia myuros. Filago minima, F. arvensis, and F. vulgaris are examples of another frequent diagnostic species in this unit. Having close relationship with ruderal vegetation, it posses a richer species composition (Romahn 1998, Dengler & Wollert 2001). The association is broadly distributed in subatlantic-submediterranean regions of Europe where it grows on primitive moving sandy soils. Arenosols contain low amounts of nutrients and alkaline cations (Preising et al. 1997) but other authors refer to soils being slightly alcalic (mean pH values 6.7Ð7.9) and moderately supplied with nutrients (Guittet & Paul 1974, Romahn 1998, Dengler & Wollert 2001). The Corniculario aculeatae-Corynephoretum canescentis Steffen 1931 nom. invers. propos. (Table 2, col. 1) is mainly an open, one- layered community. Corynephorus canescens, Spergula morisonii, Cetraria aculeata, and partly Polytrichum piliferum are the diagnostic species. One of this unit’s characteristic features is the presence of Carex arenaria and other species typical of the shallow substrates. On the other hand, it lacks meadow species of successionally advanced habitats. This association is developed on loose sands, which contain only negligible amount of humus. The reaction of the substrate is reported as medium acidic, though reaching strongly or lightly acidic values in some cases (Berger-Landefeldt & Sukopp 1965, Heinken 1990). Typically, the association represents the initial vegetation stage in the succession sequence on sands, under heavy disturbance caused by grazing it may, however, form grasslands. The optimal development occurs under suboceanic climate in north-western, north, and north-eastern European sandy lowlands (Tüxen 1928, Libbert 1933, Pas- sarge 1960, Berger-Landefeldt & Sukopp 1965, Olsson 1974, Czyz˙ewska 1992, Matuszkiewicz 2001). Only rarely it does occur on fluvioeolian sands in the Rhine Basin along the middle stretch of the river (Volk 1931, Oberdorfer 1938). The association is discerned newly in the Czech Re- public (Chytry´ et al., in litt.). A similar unit, the Violo dunensis-Corynephoretum canescentis Westhoff ex Boerboom 1960, has been reported in the literature (Heykena 1965, Wolfram 1996, Biermann 1999). The synthetic work of Berg et al. (2004) cites small differentiation between the Corniculario-Coryneph- 128 T. Cˇ erny´ et al. oretum and the Violo-Corynephoretum, the same has been observed by Wolfram (1996). The association was not included in our comparative table due to the low number of available releve´s. The community consists of coastal dunes vegetation in which it forms open stands on primitive sandy soils with low amount of nutrients and humus content, secondarily decalcified (“grey dunes”). Its habitats are shaded from wind, so the sand is already consolidated and a development of Regosol starts (Wolfram 1996). Aira praecox is a relatively constant accompanier, but hardly ever reaches abundance higher than 5% (Biermann 1999). Its area reaches from Danish Jutland across Friesian Isles to the Netherlands. The Festuco ovinae-Thymetum serpylli Tüxen 1937 (Table 2, col. 4) creates almost closed grasslands with higher species diversity. Cerastium arvense, Thymus serpyllum, Danthonia decumbens, Dianthus deltoides, Armeria maritima subsp. elongata, Potentilla argentea, and Sedum acre form the diagnostic species group. Based on its species combination, this unit falls into the Armerion elongatae. This unit represents transitional vegetation between closed sandy vegetation and the vegetation of shallow soils on solid bedrock, rich in basic cations. The association is close to the thermophilous wing of the Thymo-Festucetum ovinae Oberdorfer & Görs in Görs 1968 (the Campanulo rotundifoliae-Dianthetum del- toidis Toman 1977, described in Central Bohemia), but the synonymy published by Weeda et al. (1996) is obviously erroneous in this case (Cˇ erny´ & Neuhäuslova´ , in press). The Festuco ovinae-Thymetum serpylli is scattered across warm regions from Western to Central Europe on slightly acidic rock outcrops, where shallow soils on weathered sandy and brash deposits are being developed. This unit may be found in the Czech Republic. The Festuco capillatae-Galietum maritimi Br.-Bl. & De Leeuw 1936 (Table 2, col. 5) does not occur in the Czech Republic. It is found in the maritime belt of Northern Europe from the South Baltic coast to the Netherlands. The association’s stands are almost closed and rich in annuals and perennial forbs. The diagnostic species group consists of Trifolium arvense, T. campestre, T. subterraneum, Carex arenaria, Aphanes microcarpa, Senecio jacobaea, Galium verum agg. (G. verum var. maritimum, see pro- posed typification in Dengler et al. 2003), Vicia lathyroides, Hypochoeris glabra, and Cerastium diffusum. There is also a spectrum of species demanding higher amount of salt in soil substrate (Böcher 1945, Heykena 1965, Biermann 1999). The presence of mosses depends on the intensity of disturbance by rabbits (Möller 1975, Biermann 1999). All these features point to successively more developed stands. This unit has a close relationship to the vegetation of the Koelerion albescentis Tüxen 1937 corr. Gutermann & Mucina 1993, thanks to several common diagnostic species (Cerastium diffusum, Galium verum agg., see Biermann 1999). The Ornithopodo perpusilli-Corynephoretum canescentis Passarge 1960 (Table 2, col. 2) forms almost closed, grassy, one-layered stands, relatively rich in cryptogams (namely lichens from Cladonia and Cetraria). Ornithopus perpusillus, Aira caryophyllea, Teesdalia nudicaulis, Vegetation with Aira praecox 129

Scleranthus annuus subsp. polycarpos, and Filago minima form the diagnostic species group. Ceratodon purpureus and Racomitrium canescens are moss species concentrated in this unit. The stands of this association are more developed in succession. Washed acidic sands form substrate. The presence of this association has not been cited in the Czech Republic. In- land dunes are typical habitats in north-western Germany; this unit also occurs in the coastal regions of suboceanic north-western Europe (Weeda al. 1996).

Notes to classification within higher syntaxa Traditionally, some authors (e.g. Moravec et al. 1995) have established two classes for the vegetation of open sands and of shallow skeletal soils (the Koelerio-Corynephoretea and the Sedo-Scleranthetea, respectively). From the ecological point of view, Arenosols should be considered as a special type of shallow primitive soil (Leptosols). Both substrates share low water holding capacity (which leads to similar levels of humidity and temperature of their cover) and low nutrients availability (due to high per- meability). These factors are limiting for the group of species with similar adaptive strategy (Jentsch & Beyschlag 2003). Hence, we do not distinguish two separate classes of primitive soils. In addition, the use of the physiognomic criterion seems redundant for the extra-distinction of sandy vegetation. Both vegetation types share many species, which are considered as character species of the class level. Nevertheless, both vegetation types have extensive pool of separate character species and, in addition, the vegetation of shallow skeletal soils is typical by an increase in cryptogam species richness northward in Europe. That was the reason why both vegetation types were ranked on the subclass level (Dengler et al. 2003, 2006). Espe- cially for the Czech Republic, the vegetation with A. praecox dominated by Corynephorus canescens is known from primitive soils (rich in sandy fraction) on hard acidic bedrock, too (Kosinova´ -Kucˇ erova´ 1964). There- fore, we follow the classification concept based on the only single class, the Koelerio-Corynephoretea, in accordance with modern synopses (Czyz˙ewska 1992, Berg et al. 2004).

Acknowledgement. The study was supported by the Grant Agency of the Academy of Sciences of the Czech Republic (grant no. A6005202 “Classification of the critical syntaxa of xerothermic vegetation of the Czech Republic”). Prof. Dr. rer. nat. habil. Ernst-Ger- hard Mahn (University of Halle-Wittenberg) is acknowledged for giving us valuable comments to the previous version of the manuscript. Dr. Jürgen Dengler (University of Lüneburg) and Prof. Angelika Schwabe-Kratochwil (University of Darmstadt) kindly sent us the most recent manuscripts dealing with sand vegetation. We thank Jakub Lepsˇ for linguistic corrections. Further, we are indebted to colleagues Jirˇ´ı Danihelka, Jan Douda, Alesˇ Hoffmann, and Jirˇ´ı Sa´ dlo for providing their phytocoenological material. Zdeneˇk Kaplan kindly sent us all known historical occurrences of A. praecox in the Czech Republic stored in the FLDOK database (Institute of Botany, Academy of Sciences of the Czech Republic). 130 T. Cˇ erny´ et al.

References Arndt, A. (1956): Die Rotstraußgrasflur in der Niederlausitz. Ð Wiss. Z. Pädagog. Hoch- schule Potsdam, Math.-Naturwiss. Reihe 2: 201Ð204. Balcerkiewicz, S. & Brzeg, A. (1978): Vegetation of the forest roads in pine forests. Ð In: Wojterski, T. W. (ed.): Guide to the Polish International Excursion, 1Ð20 June 1978, p. 115Ð117. Ð Internat. Soc. Veg. Sci. & A. Mickiewicz Univ. Poznan´ , Poland. Berg, C., Dengler, J., Abdank, A. & Isermann, M. (eds.) (2004): Die Pflanzengesellschaften Mecklenburg-Vorpommerns und ihre Gefährdung Ð Textband. Ð Weissdorn-Verlag, Jena. 606 pp. Berger-Landefeldt, U. & Sukopp, H. (1965): Zur Synökologie der Sandtrockenrasen, ins- besondere der Silbergrasflur. Ð Verh. Bot. Vereins Prov. Brandenburg 102: 41Ð98. Biermann, R. (1999): Vegetationsökologische Untersuchungen der Corynephorus canescens-Vegetation der südlichen und östlichen Nordseeküste sowie der Kattegatinsel Læsø unter besonderer Berücksichtigung von Campylopus introflexus. Ð Mitt. Ar- beitsgem. Geobot. Schleswig-Holstein 59: 1Ð148. Böcher, T. W. (1945): Beiträge zur Pflanzengeographie und Ökologie dänischer Vegeta- tion. Ð Kongel. Danske Vidensk. Selsk. Naturwidensk., Math. Afh. IV/1: 1Ð163. Burrichter, E., Pott, R., Raus, T. & Wittig, R. (1980): Die Hudelandschaft “Börkener Paradies” im Emstal bei Meppen. Ð Abh. Landesmus. Naturk. Münster Westfalen 42: 1Ð69. Cˇ erny´, T. & Neuhäuslova´, Z. (in press): The “Thymo-Festucetum ovinae” complex and similar subthermophilous communities in the Czech Republic. Ð Pol. Bot. Studies. Chytry´, M. & Rafajova´, M. (2003): Czech National Phytosociological Database: basic statistics of the available vegetation-plot data. Ð Preslia 75: 1Ð15. Chytry´, M., Tichy´, L., Holt, J. & Botta-Duka´t, Z. (2002): Determination of diagnostic species with statistical fidelity measures. Ð J. Veg. Sci. 13: 79Ð90. Coomes, D. A., Rees, M., Turnbull, L. & Ratcliffe, S. (2002): On the mechanisms of coexistence among annual-plant species, using neighbourhood techniques and simula- tion models. Ð Plant Ecol. 163: 23Ð38. Czyz˙ewska, K. (1992): Syntaksonomia s´ro´ dla˛kowych, pionierskich muraw napiasko- wych. Ð Monogr. Bot. 74: 1Ð174. Dengler, J. & Wollert, H. (2001): Zum Auftreten des Vulpietum myuri in Mecklenburg und Nordostniedersachsen. Ð Bot. Rundbr. Mecklenburg-Vorpommern 35: 97Ð102. Dengler, J., Berg, C., Eisenberg, M., Isermann, M., Jansen, F., Koska, I., Löbel, S., Man- they, M., Päzolt, J., Spangenberg, T., Timmermann, T. & Wollert, H. (2003): New descriptions and typifications of syntaxa within the project ‘Plant communities of Mecklenburg-Vorpommern and their vulnerability’ Ð Part I. Ð Feddes Repert. 114: 587Ð631. Dengler, J., Löbel, S. & Boch, S. (2006): Dry grassland communities of shallow, skeletal soils (Sedo-Scleranthenea) in northern Europe. Ð Tuexenia 26: 159Ð190. Dierschke, H. (1979): Die Pflanzengesellchaften des Holtumer Moores und seiner Rand- gebiete. Ð Mitt. Flor.-Soz. Arbeitsgem., N.F. 21: 111Ð143. Eichberg, C., Storm, C., Kratochwil, A. & Schwabe, A. (2006): A differentiating method for seed bank analysis: validation and application to successional stages of Koelerio- Corynephoretea inland sand vegetation. Ð Phytocoenologia 36: 161Ð189. Ellenberg, H., Weber, H. E., Düll, R., Wirth, V. & Werner, W. (2001): Zeigerwerte von Pflanzen in Mitteleuropa. Ð Scripta Geobotanica 18: 1Ð262. Frey, L. (1994): Rozmieszczenie Aira caryophyllea i A. praecox (Poaceae) w Polsce. Ð Fragm. Flor. Geobot. Polon. 1: 5Ð17. Vegetation with Aira praecox 131

Frileux, P.-N. (1978): Aperçu de la vegetation des pelouses sećhes a` Therophytes de Haute-Normandie (Basses vallees de la Seine et de l’Eure). Ð Coll. Phytosoc. 6: 169Ð 176. Ge´hu, J.-M. & de Foucault, de B. (1978): Les pelouses siliceuses a` Therophytes de la zone littorale du Nord de la France. Ð Coll. Phytosoc. 6: 319Ð328. Guittet, J. & Paul, P. (1974): La vegetation des pelouses xerophiles de Fontainebleau et ses relations avec quelques facteurs edaphiques. Ð Vegetatio 29: 75Ð88. Hadinec, J., Lustyk, P. & Procha´zka, F. (red.) (2003): Additamenta ad floram Reipublicae Bohemicae. II. Ð Zpr. Cˇ es. Bot. Spolecˇ. 38: 217Ð288. Heinken, T. (1990): Pflanzensoziologische und ökologische Untersuchungen offener Sandstandorte im östlichen Aller-Flachland (Ost-Niedersachsen). Ð Tuexenia 10: 223Ð 257. Heykena, A. (1965): Vegetationstypen der Küstendünen an der östlichen und südlichen Nordsee. Ð Mitt. Arbeitsgem. Florist. Schleswig-Holstein 13: 1Ð135. Hülbusch, K. H. (1974): Scleranthus polycarpos in Nordwestdeutschland. Ð Abh. Natur- wiss. Ver. Bremen 38: 97Ð121. Jeckel G. (1984): Syntaxonomische Gliederung, Verbreitung und Lebensbedingungen nordwestdeutscher Sandtrockenrasen (Sedo-Scleranthetea). Ð Phytocoenologia 12: 9Ð 153. Jentsch, A. & Beyschlag, W. (2003): Vegetation ecology of dry acidic grasslands in the lowland area of Central Europe. Ð Flora 198: 3Ð25. Jentsch, A., Friedrich, S., Beyschlag, W. & Nezadal, W. (2002): Significance of ant and rabbit disturbances for seedling establishment in dry acidic grasslands dominated by Corynephorus canescens. Ð Phytocoenologia 32: 553Ð580. Kolbek, J. (2001): Piony´ rska´ bylinna´ vegetace primitivnıćh pu˚ d. Ð In: Kolbek, J. et al.: Vegetace Chrańeˇne´ krajinne´ oblasti a Biosfe´ricke´ rezervace Krˇivokla´tsko. 2. Spole- cˇenstva skal, strańı´, sutı´, primitivnıćh pu˚ d, vrˇesovisˇt, termofilnıćh lemu˚ a synantropnı´ vegetace, pp. 40Ð50. Ð Academia, Praha. Kolbek, J. & Vicherek, J. (1995): Sedo-Scleranthetea. Ð In: Moravec, J. (ed.): Rostlinna´ spolecˇenstva Cˇ eske´ republiky a jejich ohrozˇenı´. Ed. 2., pp. 88Ð92. Ð Severocˇes. Prˇ´ır., suppl. 1995. Korneck, D. (1974): Xerothermvegetation in Rheinland-Pfalz und Nachbargebieten. Ð Schriftenreihe für Vegetationskunde 7: 1Ð196, Bonn-Bad Godesberg. Kosinova´-Kucˇerova´, J. (1964): Acidophytic steppes in the region of the middle Vltava (Central Bohemia). Ð Preslia 36: 260Ð271. Krausch, H.-D. (1967): Die Pflanzengesellschaften des Stechlinsee-Gebietes. III. Grün- landgesellschaften und Sandtrockenrasen. Ð Limnologica 5: 331Ð366. Ð (1968): Die Sandtrockenrasen (Sedo-Scleranthetea) in Brandenburg. Ð Mitt. Flor.-Soz. Arbeitsgem., N.F. 13: 71Ð100. Kucˇera, J. & Vańˇ a, J. (2003): Check- and Red List of bryophytes of the Czech Republic (2003). Ð Preslia 75: 193Ð222. Lawesson, J. E. (2004): A tentative annotated checklist of Danish syntaxa. Ð Folia Geo- bot. 39: 73Ð95. Libbert, W. (1933): Die Vegetationseinheiten der neumärkischen Staubeckenlandschaft unter Berücksichtigung der angrenzenden Landschaften. 2. Teil. Ð Verh. Bot. Vereins Prov. Brandenburg 75: 229Ð348. Lindner-Effland, M. (1986): Geschichtliche Entwicklung, Vegetationszusammensetzung und Pflegekonzept für das NSG Lütjenholmer Heidedünen. Ð Kieler Notizen 18: 157Ð196. 132 T. Cˇ erny´ et al.

Matuszkiewicz, W. (2001): Przewodnik do oznaczania zbiorowisk ros´linnych Polski. Ð Wydawnictwo Naukowe PWN, Warszawa. Meusel, H., Jäger, E. & Weinert, E. (eds.) (1965): Vergleichende Chorologie der zentraleu- ropäischen Flora. Karten & Text. Ð Fischer Verlag, Jena. Möller, H. (1975): Soziologisch-ökologische Untersuchungen der Sandküstenvegetation an der Schleswig-Holsteinischen Ostsee. Ð Mitt. Arbeitsgem. Geobot. Schleswig-Hol- stein & Hamburg 26: 1Ð166. Moravec, J., Bala´tova´-Tulaćˇkova´, E., Blazˇkova´, D., Hadacˇ, E., Hejny´, S., Husa´k, Sˇ., Jenı´k, J., Kolbek, J., Krahulec, F., Kropaćˇ, Z., Neuhäusl, R., Rybnıćˇek, K., Rˇ ehorˇek, V. & Vicherek, J. (1995): Rostlinna´ spolecˇenstva Cˇ eske´ republiky a jejich ohrozˇenı´. Ed. 2. Ð Severocˇes. Prˇ´ır., suppl. 1995: 1Ð206. Morton, A. (2001): DMAP. Distribution mapping software. Ð URL [http://www.dmap. co.uk] Neˇmecˇek, J., Smolı´kova´, L. & Kutı´lek, M. (1990): Pedologie a paleopedologie. Ð Acade- mia, Praha. Newman, E. I. (1967): Response of Aira praecox to weather conditions. I. Response to drought in spring. Ð J. Ecol. 55: 539Ð556. Oberdorfer, E. (1938): Pflanzensoziologische Beobachtungen und floristische Neufunde im Oberrheingebiet. Ð Verh. Naturhist.-Med. Vereins Heidelberg 18: 183Ð201. Olsson, H. (1974): Studies on South Swedish sand vegetation. Ð Acta Phytogeogr. Suec. 60: 232Ð267. Otto, H.-W., Bräutigam, S. & Hardtke, H.-J. (1993): Floristische Beobachtungen 1991 in Oberlausitz und Elbhügelland. Ð Ber. Naturf. Ges. Oberlausitz 2: 19Ð24. Passarge, H. (1960): Zur soziologischen Gliederung binnenländischer Corynephorus-Ra- sen im nordostdeutschen Flachland. Ð Verh. Bot. Vereins Prov. Brandenburg 98Ð100: 113Ð124. Paul, P. (1975): E´ tudes expe´rimentales sur le de´terminisme de la composition floristique des pelouses xe´rophiles. III. Relations entre le substrat et la composition mine´rale des espe`ces. Ð Oecol. Plant 10: 63Ð78. Petit, D. (1978): Les pelouses a` Hieracium pilosella L. des terrils du Nord de la France. Ð Coll. Phytosoc. 6: 201Ð212. Preising, E., Vahle, H.-C., Brandes, D., Hofmeister, H., Tüxen, J. & Weber, H.-E. (1997): Die Pflanzengesellschaften Niedersachsens. Bestandsentwicklung, Gefährdung und Schutzprobleme Rasen-, Fels- und Geröllgesellschaften. Ð Naturschutz Land- schaftspfl. Niedersachs. 20: 1Ð146. Rennwald, E. (ed.) (2000): Verzeichnis und Rote Liste der Pflanzengesellschaften Deutschlands Ð mit Datenservice auf CD-ROM. Ð Schriftenreihe für Vegetations- kunde 35: 1Ð800, Bonn-Bad Godesberg. Romahn, K. S. (1998): Die Vegetation der Kremper und Nordoer Heide. Ð Mitt. Arbeits- gem. Geobot. Schleswig-Holstein & Hamburg 54: 1Ð89. Royer, J.-M. (1978): Les pelouses sećhes a` therophytes de Bourgogne et de Champagne meridionale. Ð Coll. Phytosoc. 6: 133Ð146. Sa´dlo, J. & Chytry´, M. (2001): T5 Ð Tra´vnı´ky pı´scˇin a meˇlky´ ch pu˚ d. Ð In: Chytry´, M., Kucˇera, T. & Kocˇ´ı, M. (eds.): Katalog biotopu˚ Cˇ eske´ republiky. Interpretacˇnı´ prˇ´ırucˇka k evropsky´ m programu˚ m NATURA 2000 a SMARAGD, pp. 143Ð150. Ð AOPK Cˇ R, Praha. Schaffers, A. P. & Sy´ kora, K. V. (2000): Reliability of Ellenberg indicator values for moisture, nitrogen and soil reaction: a comparison with field measurements. Ð J. Veg. Sci. 11: 225Ð244. Vegetation with Aira praecox 133

Schwickerath, M. (1944): Das Hohe Venn und seine Randgebiete. Ð Pflanzensoziologie 6: 1Ð278. Skalicky´, V. (1988): Regiona´lneˇ fytogeograficke´ cˇleneˇnı´. Ð In: Hejny´, S. & Slavı´k, B. (eds.): Kveˇtena Cˇ eske´ socialisticke´ republiky 1, pp. 103Ð121. Ð Academia, Praha. Sokal, R. R. & Rohlf, F. J. (1995): Biometry. Ð Freeman, New York. Täuber, T. (1994): Vegetationsuntersuchungen auf einem Panzerübungsgelände im Natur- schutzgebiet Lüneburger Heide. Ð Tuexenia 14: 197Ð228. Tichy´, L. (2002): JUICE, software for vegetation classification. Ð J. Veg. Sci. 13: 451Ð 453. Toman, M. (1988): Beiträge zum xerothermen Vegetationskomplex Böhmens III. Die Sandvegetation in Böhmen. Ð Feddes Repert. 99: 339Ð376. Tutin, T. G. et al. (eds.) (1964Ð1980): Flora Europaea, Vols. 1Ð5 Ð Cambridge University Press, Cambridge. URL [http://rbg-web2.rbge.org.uk/FE/fe.html] Tüxen, R. (1928): Vegetationsstudien im nordwestdeutschen Flachlande. I. Über die Vege- tation der nordwestdeutschen Binnendünen. Ð Jahrb. Geogr. Ges. 50: 71Ð93. Tüxen, R. (1974): Die Haselünner Kuhweide. Ð Mitt. Flor.-Soz. Arbeitsgem., N.F. 17: 69Ð102. Veˇzda, A. & Lisˇka, J. (1999): Katalog lisˇejnı´ku˚ Cˇ eske´ republiky. Ð Botanicky´ u´ stav AV Cˇ R, Pru˚ honice. Volk, O. H. (1931): Beiträge zur Ökologie der Sandvegetation der Oberrheinischen Tief- ebene. Ð Z. Bot. 24: 81Ð185. Wattez, J.-R. (1978): Groupements sabulicoles pionniers des carrie`res de la partie occiden- tale du Nord de la France (Thero-Airion, Panico-Setarion, Spergulo-Erodion). Ð Coll. Phytosoc. 6: 283Ð318. Wattez, J.-R., Ge´hu J.-M. & Foucault, de B. (1978): Les pelouses a` annuelles des Buttons de la Brenne. Ð Coll. Phytosoc. 6: 191Ð199. Weber, H. E., Moravec J. & Theurillat, J.-P. (2000): International Code of Phytosociologi- cal Nomenclature. 3rd edition. Ð J. Veg. Sci. 11: 739Ð768. Weeda, E. J., Doing, H. & Schamine´e, J. H. J. (1996): Koelerio-Corynephoretea. Ð In: Schamine´e, J. H. J., Stortelder, A. H. F. & Weeda, E. J. (eds.): De Vegetatie van Neder- land, Deel 3. Plantengemeenschappen van graslanden, zomen en droge heiden, pp. 61Ð 144. Ð Opulus Press, Uppsala. Westhoff, V. & van der Maarel, E. (1973): The Braun-Blanquet Approach. Ð In: Whitta- ker, R. H. (ed.): Ordination and Classification of Communities, pp. 615Ð726. Ð W. Junk, the Hague. Wittig, R. & Pott, R. (1978): Thero-Airion-Gesellschaften im Nordwesten der Westfäli- schen Bucht. Ð Natur u. Heimat (Münster) 38: 86Ð93. Wolfram, C. (1996): Die Vegetation des Bottsandes. Ð Mitt. Arbeitsgem. Geobot. Schles- wig-Holstein & Hamburg 51: 1Ð111. Zielonkowski, W. (1973): Wildgrasfluren der Umgebung Regensburgs. Vegetationskundli- che Untersuchungen mit einem Beitrag zur Landespflege. Ð Hoppea, Denkschr. Re- gensb. Bot. Ges. 31: 1Ð181.

Address of the authors: Toma´sˇ Cˇ erny´, Petr Petrˇ ı´k, Karel Boublı´k and Jirˇ´ı Kolbek, Institute of Botany, Aca- demy of Sciences of the Czech Republic, 252 43 Pru˚ honice, Czech Republic. E-mails: [email protected], [email protected], [email protected], [email protected] 134 T. Cˇ erny´ et al.

Appendix. Header data of the releve´s in Table 1