Fifty-six percent of the Central Balkan National Park is forested. However, the Park forests account for only one percent of all Bulgarian forests. They are almost evenly distributed between the southern and northern side of the mountain ridge. Of the forests within the Park, 97% are natural, and 99% originate from seed. The average age of a forest in Central Balkan National Park is 111 years; the broadleaf forests average 121 years.
Biodiversity plays an important role in forest ecosystems. Stability is vital to their resilience and resistance to outside factors. The hundred-year-old beeches, sycamores, firs, and spruces provide an optimal environment for hundreds of species of animals, fungi, and microorganisms. The two essential elements air and water, depend on the size and condition of forests. They are critical to the survival of a group of rare species, endangered on a European scale: the white-backed woodpecker, imperial and the golden eagles, bear, wolf, marten, wild cat, Ural owl, hazel hen, and bats.
Central Balkan National Park forests are essential to maintaining the ecological balance and preserving wildlife and biodiversity. Seventeen of the forest habitats identified in the Park are included on the European List of Habitats Subject to Special Protection under the European Union Directive on Habitats.
Park forests are valuable sources of natural resources (wild fruits and mushrooms); natural defenses against floods, soil erosion, and avalanches; offer excellent opportunities for rest and recreation; and are invariably beautiful.
Forest Vegetation Zones
The Park consists of six vegetation zones, four of which constitute the forest environment: the draught-resistant, thermophilic oak forest zone; the oak and hornbeam forest zone (adapted to moderate humidity conditions); the beech zone; and the coniferous zone.
· The draught-resistant, thermophilic oak forest zone occupies the lowest reaches of the forest on the southern mountainside, at altitudes of 550-650 meters above sea level, or at 800-900 meters above sea level in dry and exposed areas. The forest communities consist mostly of cerris, Italian oak, and pubescent oak. Secondary communities of oriental hornbeam have overrun areas that were once oak forests but have been cleared. Other species within this zone include hornbeam, linden, hazel, sycamore, and chestnut trees. Compact communities of red and savin juniper flourish here. Many species are either endemic (of limited geographic distribution) or relict (characteristic of bygone geological eras).
· The common durmast and common and oriental hornbeams make up the oak and hornbeam forest zone that has adapted to moderate humidity conditions. This zone dwells in altitudes up to 800-900 meters above sea level, and covers more shaded and humid areas, primarily on the southern mountain slopes. Other species within this zone include the flowering ash, linden, and hornbeam.
· At the boundary of the beech zone, there are specimens of common fir, which make up about 6% of all forests in the Park. Over 80% of all common fir forests are 100 years old or older.
· The coniferous forests are scattered in separate locations and do not form an uninterrupted, clearly defined zone. The most common homogenous coniferous community within the Park is the spruce.
· Beech Forests
Beech forests thrive in the Balkan Range, and the best-preserved and most magnificent Bulgarian beech forests are in Central Balkan National Park. They make up three-fourths of the entire wooded area within the Park while representing about 7% of all beech forests in Bulgaria. In the Stara Reka, Peeshti Skali, Severen Djendem and Boatin nature reserves, beech forests occupy 1,000 hectares, and 3,000 hectares in the Steneto and Tsarichina reserves. The Park beech forests, along with those in surrounding territories, cover an aggregate 60,000 hectares, representing the largest block of uninterrupted beech forests in Europe.
The beech trees in the Park are at an average age of 135 years, and the forest range between 800 and 1,600 meters above sea level.