Because of the various reliefs, geologic and microclimatic conditions, but also because of the variety of the soil in Papuk Nature Park, there are 10 varieties of forest communities here, covering about 96% of the area. The oak and hornbeam forests dominate the area up to 350 m above sea level. Above these areas is the beech forest zone. Beech and meals forests grow in the area above 700 m. On the southern, warm slopes of Papuk and Krndija, various varieties of oak forests flourish.
The forests of the Nature Park Papuk, especially the old ones, support the nationally important populations of endangered bird sorts. Papuk Nature Park is home to about 18% of the Croatian stock doves, listed as endangered species, and 6.6% of the European population of collared flycatchers.
