Among the first scientific studies of the Plitvice Lakes area carried out in the 19th Century was the study of plant life, which definitely speaks of the very early insight into the abundance and value of the Park’s flora, as well as its role in the creation of the Park’s fundamental phenomenon. The more detailed studies of lower plants conducted by Pevalek in 1924 and 1935 proved that fresh-water algae and moss played a significant role in forming the tufa sediments, and that the tufa and tufa-forming plants are the key factors influencing the morphology of the Plitvice Lakes.
Systematic studies of higher plants conducted by Šegulja and Krga, as late as in 1984, confirmed that the Park was also a unique phenomenon in terms of the abundance and diversity of higher plant flora. In the Park’s relatively small area there have been recorded 1,267 plant species belonging to 112 plant families.
Due to its diversity, presence of relict, endemic, rare, and protected species, many of which are listed in the Croatian Red Book of Plant Species and the IUCN Red List of Endangered Plant Species, the Park is designated as an exceptionally valuable floristic area not only in Croatia, but also in Europe and the world.
The interplay between the Park’s geographic location (60 km air distance from the sea) inland from Mt. Velebit, on the border between the continental and maritime precipitation regime at an altitude of 418-1279 m, and its base geology reflected in various karst features, enabled the development of such abundant and diverse plant life. The Park area is rich in narrowly or more widely distributed endemic species (72). Of special value are the endemic species described for the first time in this area: narrow-leaved bellflower (Edraianthus tenuifolius), Thor’s buttercup (Ranunculus scutatus), and the Dalmatian scilla (Scilla litardierei) a species abundantly distributed in the vegetation of the Park’s lowland wet meadows.
The Park is also recognised for its many species protected by the Nature Protection Act of Croatia (22 species), of which we should single out the lady’s slipper – the most beautiful orchid in Europe. Being a rare and endangered forest plant, it is listed in the Croatian Red Book of Plant Species and the IUCN Red List under the category of endangered taxa.
A special group of the Park''s flora consists of a considerable number of rare and interesting species of Croatian flora. The Siberian leopard plant (Ligularia sibirica) is a species that deserves special attention. The Plitvice Lakes National Park is the only site where this plant is found in Croatia, but also in Southeast Europe. It is on the IUCN Red List under the category of endangered taxa. In the Park area, it is found on two locations among the vegetation of the lowland wet meadows.
Another curiosity of the Park is its carnivorous plants.
The common sundew (Drosera rotundifolia) grows on the peat bogs in the Park area. Due to the rareness of such habitats, this plant belongs to the rare species of Croatian flora. In the vegetation of the Park’s lowland wet meadows we can find the common butterwort (Pinguicula vulgaris) – a rare carnivorous plant on the IUCN Red List in the category of vulnerable taxa, as well as the lesser bladderwort (Utricularia minor) – a very rare aquatic carnivorous plant.
Areas of the Park that are especially interesting and species-rich include: the narrow lakesides, the Čorkova Uvala virgin forest, Ljeskovačka bara (bog), Rudanovac and Vrelo - the most important and most valuable areas outside the lake system in hydrographical, ecological, and botanical terms. Apart from their diversity and abundant plant life, these areas are also especially important in terms of their diverse animal world.
When we mention the animal world of the Plitvice Lakes National Park, the first animal that comes to mind is its trademark – the brown bear. However, the Park’s highly diverse fauna is far greater and more valuable than the “fame” of its most attractive representative.
Ever since the Plitvice Lakes area first aroused scientific interest, the presence of many animal species has been proved and documented. Most of the invertebrates have been studied within the scope of limnological research, and by group – zooplankton, macrozoobenthos, microzoobenthos, since the aquatic habitats are of primary importance in this area. Among the lake’s frequent inhabitants are two species of crab: river and stream crab.
By their number of species, insects are the most represented in the terrestrial habitats and have sparked the interests of biologists researching the meadow and forest habitats. Deserved attention is given to a group of moths and butterflies (Lepidoptera), whose number of known species according to current research has risen to 321, of which 76 are diurnal, and 245 species are nocturnal. Researchers presume that this number constitutes only 40-50% of the potential Lepidoptera fauna. Certain habitats have been protected in the effort to preserve conditions for an undisturbed development cycle of certain important species, especially the blue butterfly of the genus Maculinea. Researchers have also explored the caddisfly group, and so far have recorded 80 species.
The number of species of certain vertebrate groups has been determined within studies conducted so far, while other groups are being studied in the scope of environmental monitoring as indicators, or separately as particularly interesting and rare species.
The features of the Plitvice Lakes and their tributaries are generally typical of trout-inhabited alpine waters. However, allochthonous populations of chub and rudd have significantly suppressed the brown trout, indigenous to these lakes. In addition, at least four more species have been proved to inhabit the waters of Lake Kozjak.
There are about twelve species of amphibians in the Plitvice National Park, which is a quite numerous vertebrate group, while reptile species are relatively few due to long winters and the thick snow cover.
The 157 bird species recorded so far is the third largest population of birds among the national parks of Croatia. Particularly interesting is the white-throated dipper – a rare bird dependent on clean aquatic habitats.
The Plitvice Lakes National Park is also home to 50 mammal species: dormouse, shrew, vole, hedgehog, pine marten, beech marten, wild boar, and others. Recent studies have determined 20 bat species living in different habitats, such as holes, caves, underneath tree bark, tree hollows, and so on. Particular interest is often aroused by the population of wolf, roe deer, red deer, wildcat, lynx, otter, and of course the brown bear from the beginning of our story, as the crown of the Plitvice animal kingdom.