Bulgaria has sixecoregions that occur entirely or partly within its borders:
- Balkan mixed forests covers most of Bulgaria
- East European forest steppe
- Pontic steppe
- Euxine-Colchic deciduous forests (only a very samll part of Bulgaria is included in this ecoregion)
- Rodope montane mixed forests
- Aegean and Western Turkey sclerophyllous and mixed forests extends into Bulgaria in the far south east corner of the country
The Balkan mixed forests ecoregion covers much of Bulgaria and bordering countries, excluding the Rodope Mountains. The vegetation of this ecoregion, especially that of the forests and grasslands, is Central European in character.
The diversity of flora and fauna is relatively high compared to the rest of Europe and there are a high number of endemic plant species. Mixed oak forests are characteristic, with Quercus frainetto as the dominant tree species. Oak forests are interspersed with pine, silver fir (Abies alba) and Norway spruce (Picea abies) forests, woodland-pastures, shiblyak and grasslands. High valleys and sheltered slopes feature forests dominated by beech (Fagus sylvatica) and hornbeam (Carpinus orientalis and C. betulus). The region’s herpetofauna is among the most diverse in Europe.
The ecoregion has a good network of protected areas; however, the changing political climate threatens them with fragmentation
East European forest steppe
Extending along the southern Black Sea coast, the vegetation in the Euxine-Colchic deciduous forests ecoregion ranges from temperate rainforest to coastal bottomland forests, peatlands and coastal sand dunes. Primarily is Turkey, the ecoregion extends acros the border to the southeastern tip of Bulgaria. The old-growth forests are home to one of the largest brown bear populations in Europe, and the migratory populations of many waterfowl, passerines, and raptors fly through the eastern end of the region. The draining of wetland habitat for agriculture, logging, and poaching are among the greatest threats to the flora and fauna.
Rodope montane mixed forests
Rodope Mountain, Greece Photograph by © WWF-Canon/Michel Gunther The Rodope Montane Mixed Forests Ecoregion is composed of the Balkan (Stara Planina) and Rhodope Massifs in the central Balkan Peninsula.
Central European in character, mixed deciduous forests (Fagus sylvatica, Carpinus orientalis, C. betula, Quercus spp.) grow on mountain slopes while the higher elevations are dominated by conifers (Abies alba, Picea albies, Pinus nigra).
On the highest peaks, forests are replaced by heaths and alpine grasslands. It is estimated that the flora of the region includes about 3,000 vascular plant species. Many are endemics from the Pleistocene glaciation, as the region served as a refuge for species that never re-established to the north.
The position of the ecoregion at the crossroads of several floristic elements (European, Alpine, and Mediterranean) also enhances floral diversity . Several of Europe’s threatened fauna species are found here such as otter (Lutra lutra), pine marten (Martes martes), imperial eagle (Aquila heliaca), cinereous vulture (Aegypius monachus), and ferruginous duck (Aytha nyroca).
Although there is a good network of protected areas, the ecoregion faces many threats from the changing political climate, expanding agriculture, and increasing tourism.
Situated in parts of Turkey, Greece, (and entending into a small part of the southwestern most corner of Bulgaria) and on some of the the Aegean Sea islands, the Aegean and Western Turkey sclerophyllous and mixed forests ecoregion enjoys a Mediterranean climate and encompasses islands, coastal areas and some inland plains. It still supports a few areas of pine forest, and hosts rare and endemic species such as oriental sweetgum and cretan palm. The endangered loggerhead turtle nests here, and fox, wolf and wild boar are included among its mammal populations. Many resident and migratory birds are found here, including threatened species such as the pygmy cormorant, Dalmatian pelican, white-headed duck, and the lesser kestrel. The dense human populations that have inhabited this ancient area of civilization have severely degraded most of the original habitat, beginning in the earlier Holocene, and accelerating in more modern times with the recent human population explosion. .
Ecoregions are areas that:
 share a large majority of their species and ecological dynamics;
 share similar environmental conditions; and,
 interact ecologically in ways that are critical for their long-term persistence.
Scientists at the World Wildlife Fund (WWF), have established a classification system that divides the world in 867 terrestrial ecoregions, 426 freshwater ecoregions and 229 marine ecoregions that reflect the distribution of a broad range of fauna and flora across the entire planet.