The Stužica National Nature Reserve (Stužický Forest) is located in the Poloniny National Park in Bukovské vrchy, on the border of Slovakia, Poland and Ukraine, and in a deep valley around the Stužica River. It was founded in 1965 and covers an area of over 761 ha. It protects the natural complex of beech and fir-beech forests of the wilderness nature with the structure of the forest in all stages of its development. Fir, beech and mountain maple are characterized by significant growth and age. Of the forest types of biotopes, beech and fir-beech forests clearly dominate.
In the stone ravines mountain maple and mountain elm grow. Many originally Carpathian and several endemic species of plants, fungi and animals live in the forest. Now it spreads from 650 m. to 1207 m. above sea level. Stužica is one of the most important protected areas in Slovakia. The area is also of great international importance.