E. Herbaceous communities and communities of lichens and mosses

Xerothermic meadows and pastures of Chrysopogon gryllus, Bothriochloa ischaemum and Festuca valesiaca

Relationships with habitat classifications. EUNIS: E1.222 Moesio-Carpathian steppes, E1.4344 Helleno-Balkan andropogonid grass steppes; PAL. CLASS.: 34.3161 Moesio-Carpathian steppes, 34.6344 Helleno-Balkan andropogonid grass steppes; HD 92/43: 6210 Semi-natural dry grasslands and scrubland facies on calcareous substrates (Festuco-Brometalia) (*important orchid sites); Bondev (1991): 129 Xerothermal grass communities with a prevalence of Dichantieta ischemi, Poaeta bulbosae, Poaeta cocinnae, Chrysopogoneta grylli and Ephemereta.

Conservation status. BDA, BC, HD.

Category. Nearly Threatened [NT - A1, 2 C1 D1 E2 F1 G1 H2 I L2].

General characteristics. This group of habitats is widely distributed in Bulgaria. They comprise phytocoenoses which have developed in different soil and climatic conditions but are united by the xerothermic characteristics of their dominant, mainly grass, species. The bedrock in many places is limestone or marl but it can also be silicate and in some places the coenoses develop on strongly sandy ground. In general, the soils are dry, mainly shallow, eroded and stony Luvic Phaeozems, Chernozems, Luvisols, Lithosols, Rankers and Rendzhinas. The localities have mostly southern exposure and different tilt, as a result of which the underground surface waters are absent and the humidity of the soil completely depends on the rainfall. Due to the existing tilt in most areas the water runs away quickly and has a more or less erosive influence. The phytocoenoses are dominated by high, tuft-forming grasses and other perennial herbaceous species from order Festucetalia valesiacae. Semi-shrubs and solitary trees that have remained from the primary wood vegetation are also part of these communities. In many parts these communities are open. They are characterized as continental or subcontinental steppes and pastures or as sub-Mediterranean xerothermic communities of perennial herbs on calcareous or sandy slopes. Often they form complexes of various petrophytic steppes on shallow, degraded humus-carbonate soils or sandy-clayey screes on slopes facing South. In the southernmost parts of the country, Sakar and Strandzha mountains, the valley of Struma river and some other localities, they occur with the coenoses of class Thero-Brachypodietea, that consist of Mediterranean grass terrophytes. The phytocoenoses are very rarely of primary origin. Mostly they replace destroyed or degraded oak forests. Many authors consider them as secondary steppes. The plant species that participate in the composition of this herbaceous vegetation are adapted to long periods of drought. There are two rest periods, one of which is in summer. Their distribution in various climatic conditions reflects in their floristic composition and structure. Additional factors of the environment such as altitude, soil characteristics, including soil acidity and anthropogenic pressure also have an impact on these habitats.

According to the Bulgarian botanical literature there are two main groups of coenoses formed in the habitat under consideration: microthermic and mesothermic steppes. Microthermic species with narrow leaves are the edificators in the group of the microthermic steppes . Their main areas of distribution are in the zones of the mesophytic beech and oak forests. There are two periods of semi-rest – in summer and winter. Main edificators are Bromus riparius, Festuca dalmatica, F. valesiaca, Poa angustifolia, and Sesleria latifolia. Most of them, growing in more humid climates, actually belong to xero-mesophytic meadow steppes of the low mountains and foothills. In the mesothermic steppes, treated as sub-Mediterranean ones, the dominant species are mesophytic tuft-forming grasses with short rhizomes. They are of more southern origin and their leaves are relatively broad. Their distribution is related to the xerothermic oak vegetation belt. There is a slight depression during the second half of the summer and complete rest in the winter in the seasonal rhythm of these coenoses. Main edificators in this group of coenoses are Chrysopogon gryllus, Bothriochloa ischaemum (= Dichanthium ischaemum),and Cynodon dactylon. The first two species are more typical because the latter is more ecologically plastic, especially with regards to soil humidity, and can also develop in mesophytic coenoses. Chrysopogon gryllus is one of the most widely distributed and plastic grasses in Bulgaria and participates in the formation of a variety of coenoses. The habitat under consideration comprises also secondary coenoses of Chrysopogon gryllus distributed in the southern parts of the Danubian plain, NE Bulgaria (Ludogorie region), East Balkan Range, Toundzha Hilly Country, Thracian Lowland, East Rhodopi Mts., the valleys of Struma and Mesta rivers, Sakar Mts., Strandzha Mts. and Dervent heights. They reach 1000–1200 m alt. in all localities. Bothriochloa ischaemum(= Dichanthium ischaemum), Dorycnium herbaceum, Euphorbia nicaeensis, Festuca valesiaca, Filipendula vulgaris, Medicago falcata, Petrorhagia prolifera, Plantago lanceolata, Potentilla recta agg., Salvia nemorosa, Taraxacum bessarabicum, Teucrium chamaedrys, T. polium, Thymus callieri subsp. urumovii, and T. pannonicus participate in their composition. Many Mediterranean species, including terrophytes, occur in these coenoses in S Bulgaria: Aphanes arvensis, Euphorbia myrsinites, E. apios, Galium parisiense, Linaria pelisseriana, Lotus aegaeus, Medicago disciformis, M. orbicularis, M. rigidula, Moenchia graeca, Neatostema apulum, Onobrychis caput-galli, Parentucellia latifolia, Trifolium cherleri, T. hirtum, T. incarnatum, and T. strictum. The participation of trees and shrubs like Crataegus monogyna, Paliurus spina-christi, Prunus spinosa is typical, and in S Bulgaria (East Rhodopi Mts. and the valley of Struma river) also typical are Jasminum fruticans, Juniperus oxycedrus. Bothriochloa ischaemum(= Dichanthium ischaemum) is a very plastic apophyte (a typical element for the Bulgarian flora but with secondarily extended distribution in the country) whose primary distribution is in rocky, warm places in Bulgaria. Its coenoses from the association Bothriochloetum (Andropogonetum) ischaemii occur in the whole country up to 1000 m alt. The largest areas are in the Danubian plain, Forebalkan, the middle part of the valley of Toundzha river, East Rhodopi Mts., South Pirin Mts., low mountains of W Bulgaria. The optimum of their development is in lowland-hilly parts of the country. The coenoses belong to the most xerothermic elements of the vegetation in the country. Their ecotopes are on slopes of different tilt and mainly facing South. The bed rock is different, but more frequently limestone. The soils are Chernozems, Luvic Phaeozems, Luvisols, and Rendzhinas, mostly shallow, eroded, poor, with very low humidity. Mediterranean species similar to the ones in the communities of Chrysopogon gryllus participate in the composition of these coenoses in the southern parts of Bulgaria. The coenoses are completely derivative and are one of the last stages of the degradation of the vegetation caused by the human activities and erosion. They originate mainly from coenoses of Chrysopogon gryllus as a result of progressive erosion and impoverishment of the soil, most often as a result of grazing and trampling by cattle. Therefore, it is common that the coenoses of Chrysopogon gryllus close to human settlements are replaced by these of Dichanthium ischaemum. More often the grass cover is scattered and its soil protection and water regulating functions are restricted. Apart from the monodominant coenoses also a great number of polydominant ones occur, such as Chrysopogon gryllus, Cleistogenes serotina, Cynodon dactylon, Festuca valesiaca, F. dalmatica, F. rupicola, Poa angustifolia, and P. bulbosa. Some phytocoenoses are of more restricted, even local distribution. In some regions Fumana procumbens, Helianthemum salicifolium, Satureja montana, Stipa capillata, Thymus longedentatus,Trachynia distachya(= Brachypodium distachyon), Trifolium spp., etc. play a significant role in the coenoses. The floristic composition of the communities of Dichanthium ischaemum is very diverse. Since most often they derive from communities of Chrysopogon gryllus part of their floristic composition is similar to the coenoses of the latter; however, it also depends on their geographic distribution. The following species occur more frequently: Aegilops cylindrica, A. geniculata, A. triuncialis, Ajuga chia, Arenaria serpyllifolia, Asperula cynanchica, Astragalus onobrichys, A. spruneri, A. monspessulanus, Bombycilaena erecta, Convolvulus cantabrica, Crepis sancta, Eryngium campestre, Euphorbia myrsinites, E. cyparissias, E. apios, Leontodon crispus, Lotus aegaeus, Medicago minima, Ononis arvensis, Petrorhagia prolifera, P. velutina, Plantago lanceolata, P. subulata, Polygala major, P. monspeliaca, Potentilla recta agg., Pterocephalus papposus, Salvia viridis, Sanguisorba minor, Scabiosa micrantha, S. ochroleuca, S. sicula, Sideritis montana, Trifolium scabrum, T. angustifolium, T. arvense, T. setiferum, Valerianella discoidea, V. dentata, etc. Grazing has caused ruderalization and degradation of the habitat and consequently spiny, poisonous or inedible species (Cichorium intybus, Berteroa incana, Carduus nutans, Centaurea diffusa, Cephalaria transsilvanica, Chondrilla juncea, Convolvulus arvensis, Conyza canadensis, Crepis setosa, Cynodon dactylon, Daucus carota, Euphorbia cyparissias, Picris hieracioides, Torilis arvensis, Trifolium arvense, Xeranthemum annuum) also occur. Festuca valesiaca participates very often in the second herbaceous layer of the communities of Chrysopogon gryllus. In some places (mainly stony areas), mostly as a result of grazing, Chrysopogon gryllus can become an edificator. These coenoses occur in the whole country up to 1200–1300 m alt. in the belt of beech forests but most frequently they occur in the Danubian plain, Forebalkan, the middle part of Toundzha river valley, East Rhodopi Mts., the mountains of West Bulgaria. They belong to the xerophytic ecological type. The ecotopes are wide low areas, flat areas, slanting slopes, plateau-like heights. The bed rock is variable, but most often the coenoses richest in species are on limestone. The soils are Chernozems, Luvic Phaeozems, Luvisols, and more rarely Rendzhinas. They are well developed, but with more dense surface as a result of grazing and trampling by cattle. Humidity is low, especially in the second part of the summer. In the low mountains of W Bulgaria there are coenoses of Festuca valesiaca with more expressed mesophytic characteristics (Filipendula vulgaris, Agrostis capillaris, etc. occur very often). These coenoses can be considered as meadow steppes. There are also more xerophytic coenoses in which some pontic-steppe elements occur (Adonis vernalis, Iris reichenbachii, Paeonia tenuifolia, Salvia argentea, S. nutans, and S. pratensis).Almost all coenoses are of secondary origin. They are xerothermic and herbaceous of transitional character between the meadow and pasture vegetation. The ratio between the mesophytic and xerophytic species depends upon the duration and intensity of grazing.

Intensive grazing causes the disappearance of typical meadow species most of which are mesophytic (Alopecurus pratensis, Anthericum ramosum, Brachypodium pinnatum, Briza media, Bromus commutatus, B. mollis, B. racemosus, Carum carvi, Coronilla varia, Elymus repens, Festuca nigrescens, Linum austriacum, Lolium perenne, Lotus corniculatus, Moenchia mantica, Ornithogalum sphaerocarpumPoa pratensis, P. sylvicola, P. trivialis, Stellaria graminea, Trifolium campestre, T. montanum, T. ochroleucon, T. pratense,species from Orchidaceae, etc.). Mesophytic species that are more resistant to grazing form a considerable part of the floristic composition of the pasture coenoses: Berteroa incana, Bromus inermis, B. mollis, B. tectorum, Colchicum autumnale, Dactylis glomerata, Elymus repens, Filipendula vulgaris, Lolium perenne, Luzula campestris, Ranunculus acris (from the alliance Mesobromion), etc. As a result of the grazing regime practiced for ages the natural selection has lead to a specific vegetation consisting of species that can endure mechanical damage and to develop on trampled, dense and badly aerated soils that are often very rich in nitrogen and other salts introduced by the manure. The following species occur: Alyssum alyssoides, A. minutum, Bromus tectorum, Bothriochloa ischaemum(= Dichanthium ischaemum), Cynodon dactylon, Hordeum murinum, Petrorhagia prolifera, Poa annua, P. bulbosa, etc. Some species are so well adapted to the environmental conditions that their distribution is carried out partly by the cattle (Matricaria trichophylla, Plantago lanceolata, Rumex acetosella, Trifolium repens, etc.). Together with these species, as a result of the human activities, some semi-ruderals or ruderals occur such as Chenopodium botrys. Hence the pasture coenoses can be transitional coenoses between meadows and ruderal vegetation.

The xerophytic vegetation in Europe (including Bulgaria) belongs to class Festuco-Brometea. It unites dry to semi-dry herbaceous and shrub steppe communities, continental or subcontinental (Euro-Siberian) communities (Festucetalia valesiacae), as well as phytocoenoses form the Atlantic and sub-Mediterranean regions. Depending on their origin the latter can be classified as primary– alliance Xerobromion (with main species Bromus erectus, Euphorbia seguerana, Hippocrepis comosa, Silene otites and other species from Festucetalia valesiacae) and secondary – alliance Mesobromion (all belonging to order Brometalia erecti). In Bulgaria these coenoses are widely distributed and are typically rich in orchids that develop in more humid climate.

Characteristic taxa.

Distribution in Bulgaria. The habitat is widely distributed in the whole country up to 1200–1300 m alt. excluding the loess heights along the Danube, foothill mountains of West Bulgaria, Forebalkan and S Dobrudzha. This habitat type occurs more frequently in areas with expressed Mediterranean climatic influence in the southern parts of the country.

Conservation importance. The caespitose grasses with dense cover have excellent anti-erosion and water-regulating functions. Their phytocoenoses form the meadows and pastures in Bulgaria and are good sources of forage, medicinal plants, fungi, etc. A major part of these coenoses is destroyed due to their overexploitation. Many rare, protected and endangered species participate in the composition of the steppe vegetation. Some fungi of conservation value also occur in this habitat: Amanita vittadinii, Endoptychum agaricoides, Entoloma incanum, Gastrosporium simplex, Hygrocybe calyptriformis, H. ceracea, H. punicea, Lepista luscina, Pisolithus arhizos,and Polyporus rhizophillus.

Threats. Main threat is ploughing, urbanization, industrial, agricultural and communication infrastructure, overgrazing that leads to xerophytisation, ruderalization and changes in their structure and ecological characteristics. General aridisation of the climate, fertilization of the neighbouring agricultural land, stone pits, digging activities, deposition of industrial and household waste, invasion of alien species, developing of tree and shrub vegetation.

Conservation measures taken. The habitat is included in Annex № 1 of the national Biodiversity Act and is of conservation priority when it is an important orchid site. Some of the most representative localities are in sites of the European Ecological Network NATURA 2000 in Bulgaria.

Conservation measures needed. Monitoring of the state of the pastures, proclamation of the most representative pastures as protected areas, correct management of pastures through restriction of grazing and changes of the land use for construction activities and extraction of minerals.

References. Ganchev et al. 1964; Tzonev 2002.

Authors: Rossen Tzonev, Veska Roussakova

Xerothermic meadows and pastures of Chrysopogon gryllus, Bothriochloa ischaemum and Festuca valesiaca (distribution map)