The protected area covers most of the mountain Ograzhden and the southern part of mountain Malesh. In the ridge parts, there are old beech and oak forests and low populated areas. Important are the valleys of river Lebnitsa and Ribnik.
The area keeps unaltered by human activity riparian habitats. Along the Lebnitsa river are one of the three most representative places in Bulgaria of venerable plane forests. The area is one of the few places in Bulgaria with seed oak forests. In the lower parts of the area in the past there were forests of juniper.