“Osetno” nature reserve was created on 14 November 2008. Spreading on over 111 hectares, it protects forest habitats as well as rare and endangered species of fungi. A total of 240 species of fungi grow in the reserve, including 7 species under protection, and 53 rare and endangered species. The main objective of the reserve is to protect and maintain mushrooms, which can be found in the forests with plenty of decaying wood. The rare species of fungi found in the nature reserve include Mycoacia uda and dark-scaled knight. Visitors must keep to the marked green trail named after Bolesław Czwójdziński. Picking any mushrooms in the nature reserve is strictly prohibited.