50 Roubles Berezinsky Biosphere Nature Reserve. Beaver

The Berezinsky Biosphere Reserve, established in 1925 along the Berezina River, was one of the first protected territories in Soviet Belarus and gained UNESCO biosphere status in 1978. The European beaver (*Castor fiber*) was effectively extinct in the region by the early twentieth century due to unrestricted hunting; Berezinsky became a primary site for the species' reintroduction and recovery, a program that began in the 1930s and is now considered one of the more successful mammal rehabilitation efforts in Eastern European conservation history.