08H3

H. Inland rock habitats

Calcareous rocks with hasmophytic vegetation

Relationships with habitat classifications. EUNIS: H3.2A12 Rhodopi calcicolous hasmophytes communities, H3.2A13 Balkan Range calcicolous hasmophyte communities; PAL. CLASS.: 62.1A12 Rhodopi calcicolous hasmophyte communities, 62.1A13 Balkan Range calcicolous hasmophyte communities; HD 92/43: 8210 Calcareous rocky slopes with hasmophytic vegetation.

Conservation status. BDA, HD.

Category. Vulnerable [VU – A1, 2 B2 D2 H2 I J].

General characteristics. The vertical or very steep calcareous rock walls and the sharp rock crests which often occur between the cirques are amongst the most unfavourable habitats for living organisms. The plants here are subjected to a direct impact of climatic factors, determined by the altitude, slope, exposure (strong radiation of the crests and the southern slopes, high day /night and seasonal temperature amplitudes, strong winds, absence of snow cover) and the characteristics of the rock substrate: acidity (obligate calcicoles or plants indifferent to this factor may occur), humidity (very often close to zero or permanently very high values), etc. The soil cover is almost absent although a small quantity of fine soil can accumulate in the crevices, or it is very poorly developed (rendzic soils). The single individuals or groups of plants are at large distances from each other, and the biotic relations between them are very week. In most cases the organisms exists in a self-created environment (out-environment). The total projective cover is negligible. The combination of plants in the specific rock habitat is a matter of chance. Phytocoenotic selection is absent; the combination of plant species depends only on the ecological conditions. Therefore, an unlimited number of syntaxa can be described. The limited genetic exchange between the taxa in the different mountains also have a significant impact on the species composition, hence there are favourable conditions for endemic speciation. A speciation centre of major importance is the one in Pirin Mts., mainly in the highest parts. A specific environment exists in the crevices of the steep rock walls consisting of limestone-rich crystalline schists and marble. It is a prerequisite for the existence of endemic species and subspecies – local, Bulgarian and Balkan ones. They find the optimal conditions for their individual and phytocoenotic development. The following species occur at this altitude: Dryopteris villarii,Galium demissum subsp. stojanovii, Saxifraga adscendens subsp. parnassica, S. exarata subsp. pirinica, S. ferdinandi-coburgi, S. oppositifolia, S. spruneri,etc. Potentilla apennina subsp. stojanovii is endemic to Pirin and Slavyanka Mts., and is one of the most typical hasmophytes in Bulgaria. It occurs mainly in the subalpine belt of Pirin Mts., on southern slopes mostly of steep marble rock at 2300–2600 m alt. The following species also frequently occur: Alyssum cuneifolium subsp. pirinicum, Androsace villosa, Asplenium fissum, Campanula cochlearifolia var. pirinica, C. rotundifolia var.velutina, Kernera saxatilis, Leontopodium alpinum subsp. nivale, Papaver degenii, Saxifraga ferdinandi-coburgi, S. luteoviridis, S. oppositifolia, S.pseudosancta (= S. juniperifolia), Sesleria korabensis, Silene saxifraga, Veronica kellererii, Viola grisebachiana, etc. Among these are some endemic species. The cryptogamic species have a total cover below 10% and are represented by Hymenostylium recurvirostrum, Toninia candida, Tortella tortuosa etc. The rock crevices, cracks and crests at 1900–2000 (2300) m alt., which are very steep, are also rich in species. Alchemilla pirinica, Asperula suberosa, Asplenium ruta-muraria, A. trichomanes, A. viride, Campanula cochlearifolia var. pirinica, Carex kitaibeliana, Euphrasia salisburgensis, Festuca pirinica, Hieracium pannosum, Hypochoeris maculata subsp. pelivanovicii, Kernera saxatilis, Micromeria cristata, Rhodax canus, and Saxifraga paniculata are among the most typical species. Some are very frequent, others are rarer. Among the species that are more frequent are Androsace villosa, Asplenium fissum, A. ruta-muraria, A. trichomanes, A. viride, Carum rigidulum subsp. bulgaricum (rare species, Balkan endemic), Cystopteris fragilis, Ceterach officinarum, Gymnocarpium robertianum, Saxifraga adscendens subsp. adscendens, S. luteoviridis, and S. paniculata. Many of the hasmophytes that grow in Pirin Mts. occur also in Slavyanka Mts. together with some rare species like Malcolmia angulifolia that occur only in that mountain. Calcareous rocky outcrops, walls, rock crowns, and peaks also occur in the Balkan range, mainly on the high mountain ridges. Many rare, endemic and protected species occur there. The exposure is variable, but in general it does not play a significant role in the determination of the species composition of the coenoses because the conditions are unfavourable everywhere. The species adapted to such conditions have limited abundance. The coenoses are open and with very diverse composition. Together with frequently occurring species are some very rare, obligate calcioles or species indifferent to the rock substrate: Achillea ageratifolia, Alchemilla plicatula, Allium flavum, Androsace villosa, Anthyllis montana, A. vulneraria subsp. polyphylla, Arctostaphylos uva-ursi, Asperula capitata, Asplenium ruta-muraria, A. septentrionale, A. trichomanes, Astragalus depressus, Daphne blagayana, Draba aizoides, D. lasiocarpa, Erysimum drenowskii, Iberis sempervirens, Juncus trifidus, Juniperus sabina, Jurinea glycacantha, Laserpitium siler, Luzula italica, Micromeria cristata, M. frivaldszkyana, Primula frondosa, Rhodiola rosea, Saxifraga paniculata, S. rocheliana, Sesleria rigida etc. There are calcareous rocky outcrops in the Balkan Range at lower altitudes as well: Vrachanski karst area, Sinite Kamani area near Sliven, etc. The following species occur there: Achillea clypeolata, Chamaecytisus calcareus, Daphne oleoides, Dianthus petraeus, Festuca xanthina, Inula aschersoniana, Pulsatilla hallerisubsp. rhodopaea, Sedum grisebachii, Stipa epilosa etc. Communities dominated by Rhamonda serbica, a Balkan endemic and rare Bulgarian species, or communities in which its distribution is limited occur in West Forebalkan, up to 1000 m alt. on calcareous rocks. They cover relatively small areas. The coenoses of Silene alpina are very limited (only in Vratzata area). Rhodopi Mts. are also a centre of speciation and refugium for rare and endangered hasmophytes such as Arenaria rhodopaea, Saxifraga aizoides, S. ferdinandi-coburgi, S. sempervivum, S. stribrnyi, Scabiosa rhodopensis, Viola grisebachiana. Some more widely distributed species such as Inula aschersoniana, Morina persica etc. also occur. Among the most well known hasmophytes from Rhodopi Mts. occuring also in the Balkan Range and with a more limited distribution in Sredna Gora Mts. is the rare, Balkan endemic Haberlea rhodopensis. It is found mainly on calcareous rocks but also on silicate in Rila and Vitosha Mts. The open calcareous rocky outcrops are of limited area and the species composition is not specific. Among the rare species, mainly in Rila Mts., are Androsace villosa, Anthyllis vulneraria, Arenaria ciliata (more typical for screes), Cystopteris regia, Primula halleri etc. As the altitude increases the areas covered by rocky outcrops and their species composition decreases. Some of the above mentioned species typical for high mountain areas occur together with species whose vertical range of distribution is more limited such as Asplenium septentrionale, A. trichomanes, A. viride, Ceterach officinarum, Goniolimon dalmaticum (in Slavyanka Mts., a rare species), Gymnocarpium robertianum, and Valeriana montana. The hasmophytic coenoses below 500 m alt. occur in the Forebalkan, the southern parts of the Danubian plain, and in the valleys of the larger rivers Iskar, Vit, Osam, Yantra, Rusenski Lom. Canyons, gorges and meanders are shaped in Cretaceous limestone. Similar, although smaller, karst rock crowns occur in Ludogorie area, Sucha Reka and Harsovska Reka dry valleys, near Isperich and in the areas of Shumensko and the Provadiisko-Royaksko plateaus. The height of the rock crowns varies from several to several tens of meters (100 m near Sadovets village, Pleven region and Karlukovo village, Lovech region). The most frequent hasmophytes in these areas are Alyssum saxatile, Centaurea rutifolia, Galium album, G. flavescens, G. lucidum, Parietaria lusitanica, Poa compressa, Seseli rigidum, and many lichens and ferns (Asplenium ruta-muraria, A. trichomanes, Ceterach officinarum, Cystopteris fragilis, Polypodium vulgare). Among the hasmophytes are endemic taxa: Campanula euxina (Madara plateau), Celtis glabrata (Danubian plain), Dianthus petraeus subsp. noaenanus, Moehringia jankae, Seseli degenii, Silene velcevii (C Forebalkan) etc.

Hasmophytic coenoses in West Bulgaria are similar in composition: Campanula versicolor, Centaurea rupestris (= Colymbada finazzeri), Edraianthus serbicus, Inula aschersoniana, Thalictrum foetidum etc. occur on the vertical rocks in the valley of Struma and Shagava rivers in Zemen and Konyavska Mts., Erma river near Tran town. Apart from the hasmophytes, this habitat type is suitable for other species which are more typical for screes, stony meadows or which have an even wider ecological range of distribution. Such species are Armeria alpina, Carex kitaibeliana, Cerastium alpinum, C. lanatum, Festuca valesiaca, Galium anisophyllon, Juniperus sibirica, Melica ciliata, Pinus mugo, Poa alpina, P. nemoralis, Potentilla cinerea, Rosa spp., Sesleria latifolia etc. Some tree species can grow in the crevices of the calcareous rocks as well: Fraxinus ornus, Ostrya carpinifolia, Pinus nigra, P. sylvestris,and shrubs Arctostaphylos uva-ursi, Chamaecytisus absinthioides, Cotinus coggygria, Daphne oleoides, Juniperus oxycedrus, Syringa vulgaris etc. Typical hasmophytic vegetation on limestone in the high mountains of the southeastern part of the Balkan Peninsula belong to a specific alliance Ramondion nataliae from order Potentilletalia caulescentis of class Asplenietea trichomanis. The syntaxonomy of this group has not been studied so far.

Characteristic taxa.

Distribution in Bulgaria. Whole country, from 100 to 2925 m alt.

Conservation importance. Many endemic and legally protected species and syntaxa occur in this habitat: Alchemilla pirinica, A. plicatula, Allium montanum, Alyssum cuneifolium subsp. pirinicum, Androsace villosa, Arabis ferdinandi-coburgi, Arenaria pirinica, A. rhodopaea, Asperula capitata, Aubrieta columnae, A. gracilis, A. intermedia, Campanula cochlearifolia var. pirinica, Carum rigidulum subsp. bulgaricum, Centaurea parilica, Cystopteris regia, Daphne blagayana, Dianthus nardiformis, Draba aizoides, D. athoa, D. carinthiaca, D. lasiocarpa, D. tomentosa, Erysimum drenowskii,Galium demissum subsp. stojanovii, Goniolimon dalmaticum, Haberlea rhodopensis, Hypochoeris maculata subsp. pelivanovicii, Juniperus sabina, J. glycacantha, Kernera saxatilis, Laserpitium siler, Leontopodium alpinum subsp. nivale, Malcolmia angulifolia, Micromeria cristata, M. frivaldszkyana, Minuartia stojanovii, Papaver degenii, Polypodium cambricum, Potentilla apennina subsp. stojanovii, Primula frondosa, P. halleri, Ramonda serbica, Rhodiola rosea, Saxifraga adscendens subsp. discolor, S. exarata subsp. pirinica, S. ferdinandi-coburgi, S. luteovirirdis, S. oppositifolia, S. paniculata, S. rocheliana,Saxifraga pseudosancta (= Saxifraga juniperifolia), S. spruneri, Scabiosa rhodopensis, Seseli bulgaricum, S. degenii, S. rhodopeum, Silene saxifraga, S. velcevii, Toninia candida, Veronica kellererii, Viola delphinantha, V. grisebachiana etc. The fungus of conservation value Arrhenia spathulata also occurs.

Threats. Hazardous air pollution, construction activities and pollution in neighbouring areas, exploitation of limestone, intensive tourism, grazing, collecting of flowers, can cause structural changes in the coenoses, reduction in the number of individuals and affect the critical state of the habitat as a whole.

Conservation measures taken. A significant part of the rock areas are within protected areas: Rila, Pirin and Central Balkan National Parks, Vrachanski Balkan, Russenski Lom, Sinite Kamani and Shumensko Plato Nature Parks, Trigradsko Zhdrelo Protected Site, Chernelka Nature Monument and sites from the European Ecological Network NATURA 2000.

Conservation measures needed. To include the parts of this habitat type in already existing or establish new protected areas in order to protect it. Elaboration of an interpretative program for the tourists aiming at the protection of the habitat.

References. Meshinev et al. 2000; Mucina et al. 1990; Roussakova 2000; Simon 1958.

Authors: Chavdar Gussev, Veska Roussakova


Calcareous rocks with chasmophytic vegetation (distribution map)