The territory of Bulgaria is a part of the European-Western Siberian biogeographical region of the Palearctic kingdom and is situated in the biomass of deciduous and mixed forests of temperate latitudes in the northern hemisphere.
The territory of the Chervenata Stena biosphere park is located in two biogeographical regions: Mountain biogeographical region, Rila-Rhodopes subregion – part of the core and buffer zone and the Central Bulgarian region, subregion of the Upper Thracian lowland – here are included the lower parts of the core, the buffer and a large part of the transition zone, covering the plains settlements from the territory of the municipality of Assenovgrad.
The territorial location of the park in two biogeographical regions and the diversity of relief, climatic and soil characteristics determine a variety of habitats and a mosaic of ecological systems which are an appropriate ecological environment for the representative flora and fauna. For this reason, the territory of the Chervenata Stena biosphere park comprises different types of ecosystems, suggesting a number of opportunities for the development of human activities aimed at sustainable development and sustainable utilization of natural resources. For instance, the mountain biogeographical region is the only one in Bulgaria, where ice-age relics of animals and plants are distributed, and the core zone of Chervenata Stena Biosphere Park is a typical example of this. And the flat parts of the transition zone, situated in the sub-region of the Upper Thracian Plain, feature a more uniform relief as a large part of the area is arable land where agro-ecological systems are developed. Greater biodiversity has been preserved along the rivers and in the plain forests in the lower parts of the transition and buffer zones.
The core area of the Chervenata Stena biosphere park is situated in the Central Rhodopes. Its territory covers the valleys of the Sushitsa and Chepelare rivers, the Dobrostan hill and the high, steep cliffs of the Chervenata Stena peak, which is 1.500 m high. It is featured by a variety of surface reliefs and sharp differences in altitude. The area around the Sushitsa River is the most difficult part to access the reserve . A steep and rocky slopes have been formed along it, reaching a height of up to 800 m. It is also one of the richest in caves region in Bulgaria – Dobrostan pearl, Topchika, Yamata and Hralupata and others.
The diversity of biotopes in the park is determined on one hand by the climatic conditions in this part of the Rhodope Mountains and on the other by the specifics of the basic rock and the soil cover, formed on it as well as by the variety of forms of meso- and microrelief. Deep valleys, flattened ridges, hillsides and riparian overgrown habitats, forests and open rock outcrops host a variety of abiotic conditions in which different organism groups find the right environment for development.
The Chervenata Skala Biosphere Park possesses a complex of unique natural features (relief, altitude, composition of the main rocks, soil and climatic conditions), which determine the richness of flora, mycotics, fauna, natural habitats represented with a high percentage of protected , endemic and relict species. As a result, the biodiversity of the biosphere park is of high environmental importance both at national, European and world level. The territory of the core and buffer zones of the biosphere park is inhabited by a number of species of conservation significance:
According to recent studies conducted within the framework of the development of the Core Zone Management Plan in 2015, the following species of conservation significance have been identified:
– 2 species of macromycetes of conservation significance included in the Fungal Red List in Bulgaria (Discinia ancilis – VU; Calocybe ionides – DD);
– 28 species (3.5% of the vascular flora) included in the second edition of the Red Data Book of the Republic of Bulgaria, Volume 1, Plants and Fungi (Peev, edition 2011), 18 species of which are under ‘Endangered by Extinction’ category (EN), 8 species are Vulnerable (VU) category and 2 species are Critically Endangered (CR) category.
– 57 species of vascular plants (5.3% of the core zone flora) are endemic – Balkan endemics (45 species) and Bulgarian endemic species (12 species);
– 38 of the vascular plants (3.5% of the core zone flora) are included in Appendix 3 of the Biodiversity Act;
– 3 species of the vascular plants are included in Annex II to Council Directive 92/43 / EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora – Cypripedium calceolus (Lady’s Slipper), Echium russicum (red-flowered viper’s grass ) and Himantoglossum caprinum (common jelly);
– 20 plant species are protected by the Convention on International Trade in Endangered Species of Animals and Plants (CITES, 1973) – all members of the Orchidaceae family and one species of the Amaryllidaceae family (Galanthus elwesii);
– Tertiary relicts are 58 species and the glacial – 6 species.
– 5 invertebrate species are included in the the International Union for Conservation of Nature (IUCN) Red List – Libelloides macaronius; Carabus intricatus; Cerambyx cerdo; Morinus asper; Parnassius apollo;
– 6 invertebrate species are included in Directive 92/43 of the Council of the European Economic Community for the conservation of natural habitats and of wild fauna and flora – Paracaloptenus caloptenoides, Cerambyx cerdo, Morinus asper funereus, Euplagia quadripunctaria, Parnassius apollo, Parnassius mnemosyne;
– 2 invertebrate species are included in Appendix 3 of the Biodiversity Act – Cerambyx cerdo, Parnassius apollo;
– 13 species of molluscs are endemic – – local endemic (2 species): Belgrandiella dobrostanica, Macedonica hartmuti; endemic species for the Western Rhodopes (4 species): Laciniaria macilenta, Laciniaria bajula, Bulgarica fraudigera, Tandonia pinteri; Bulgarian endemic species (4 species): Bulgarica fritillaria, Bulgarica bulgarica, Cattania rumelica, Cattania haberhaueri; Balkan endemic species (3 species): Grossuana angeltsekovi, Bulgarica denticulata, Tandonia serbica.
– 13 of the established bird species fall under the Red Data Book of the Republic of Bulgaria (2012). Endangered by Extinction (EN) are 5 species (Accipiter gentilis – Northern goshawk, Accipiter nisus – little hawk Tetrao urogallus – capercaillie, Alectoris graeca – mountain cricket, Dendrocopos leucotos – white-backed woodpecker), vulnarable (VU) – 5 species (Pernis apivorus- honey buzzard, Buteo rufinus – white-tailed buzzard, Aquila chrysaetos – rock eagle, Dendrocopus martius – black woodpecker, Ficedula semitorquata – semicollared flycatcher), near threatened (NT) – 1 species (Corvus corax – common raven) and least concern (LC) are two species (Bonasa bonasia – hazel, Emberiza cia -head-bearded owl).
– 43 species of birds (out of 49 species of birds established in the Chervenata Stena Biosphere Park, 88%) are protected for the territory of the country, according to the Biological Diversity Act;
– 20 species of bats (60.6% of the bat species in the country) are included in the Biological Diversity Act – Annex 2 and 3, in Directive 92/43, Red Data Book of Bulgaria, vol. 2 Animals, IUCN;
– 8 species of mammals (without bats) are enlisted in the Red Data Book of Bulgaria, vol. 2. Animals (2012) – under category Vulnerable (VU) – marbled polecat (Vormela peregusna), otter (Lutra lutra), European ground squirrel (Spermophilus citellus) and wolf (Canis lupus); also, in the category of Endangered (EN) – brown bear (Ursus arctos), wild goat (Rupicapra rupicapra), Eurasian golden marten (Martes martes) and wild cat (Felis silvestris).