With regard to plant and animal diversity, the area of the Plitvice Lakes belongs to the most significant areas of Croatia. This is due to climatic conditions and to the location of this area, since the lakes are far away from polluted and noisy cities or industrial plants. In the partially primeval beech and fir forests various rare species, such as the brown bear and wolf, have survived. At the Plitvice Lakes, all species continue to exist that have already existed before the coming of man. This is a rare case worldwide.
The lakes of Plitvice are a result of century-old processes and the sedimentation of chalk, which is abundantly available in the waters of this karst area. These sedimentations are called tufa or travertine.