Where the plain touches the Black Sea, varieties of tropical or subtropical vegetation appear. Vegetation is dense along the Kamchiya River and on the banks of a few of the smaller streams as they approach the sea. Reeds, lianas, exotic flowers, and huge old trees that grow nowhere else in the country flourish in this region.
In the southern Rodopi, where a few of the river valleys—those of the Struma, Mesta, and Maritsa, for example—open to the south, the vegetation is typically Mediterranean. Natural species include the Mediterranean scrubby underbrush, maquis, and an assortment of flowering plants and shrubs. Vineyards and subtropical fruit grow well in these valleys. Such areas produce the country's peaches, figs, and peanuts.
Mountainous regions feature Alpine meadows and pastures above the tree line, where the terrain permits, and conifer forests immediately below the tree line. Deciduous trees are native to all of the uplands of the country with tolerable elevations. Beech predominates at intermediate elevations, particularly on northern slopes, and oak, on the lower foothills. There are dense elm, oak, and ash forests at lower elevations in the Kamchiya River valley where it descends from the eastern part of the Stara Planina. Scrub and brush prevail at all upland elevations where terrain and soil conditions are poor or where the original forest has been removed and has not been replaced.
The Stara Planina has grassy meadowland and pastures on rounded summits and higher slopes. In the springtime these higher lands may also be brilliant with wild flowers and flowering shrubs. Cherry laurel, for example, grows wild over wide areas. The meadows usually give way to beech and to other mixed deciduous forests at lower elevations. Mixed forests may contain varieties of oak, chestnut, hornbeam, elm, and ash.
The most valuable forests are in the Rodopi, although many of them are interspersed among inaccessible craggy hills. A majority of the country's conifers, both the natural forest and those that have been planted in preference to the slower growing deciduous, are in the higher Rodopi, including the Rila and the Pirin. The most common of the conifers are pine and fir. At elevations beneath those dominated by the conifers, the mixture of broad-leaved deciduous trees is similar to that of the Stara Planina. Of the forest area, only about one-half has tall timber. Scrub on the remainder, however, serves to stabilize the soil of the forest lands against erosion and to slow the runoff of water. The rare and exotic edelweiss can be found on the higher slopes of the Pirin.
The clearing of forestland and the increase in human population have driven most of the larger wildlife from their natural habitats, except in the higher and more rugged terrain. Of the larger species, some bears, wild boars, wild goats, wolves, elk, and several species of deer continue to exist naturally. Foxes, wildcats, polecats, squirrels and other rodents, and hare—better able to adjust to existing conditions—are also surviving.
Quail, turtledoves, wild fowl, and other game birds are hunted in restricted seasons. Hunting seasons are also provided for some of the deer species; the seasons usually last between two and four months, depending upon the need to protect the animal, between the months of August and February. There are bounties on wolves and foxes. Wildcats, falcons, and hawks are also considered harmful and may be killed at any time. The polecat—in Europe the Mustela putorius, a fetid-smelling member of the weasel and otter family—is a bloodthirsty, insatiable hunter that terrorizes poultry. It also may be exterminated.
The many caves in limestone-dominated regions have given rise to various types of blind fauna. The largest of them are crabs, but most are insects, including mosquitoes, butterflies, spiders, locusts, and common flies. Although they are blind, exposure to light is usually fatal to such species.
Rivers contain several kinds of freshwater fish, the most plentiful of which are sturgeon, whitefish, and European carp. Mackerel account for the largest percentage of fish taken from the Black Sea. There are no sharks or other dangerous fish in these waters, but a rare Black Sea seal breeds along the rocky coast north of Varna.