Although Slovenia is a small country, there is an exceptionally wide variety of habitats. In the north of Slovenia are the Alps (namely, Julian Alps, Karavanke, Kamnik Alps), and in the south stand the Dinarides. There is also a small area of the Pannonian plain and a Littoral Region. Much of southwestern Slovenia is characterized by Kras, also known as the Classical Karst, a very rich, often unexplored underground habitat containing diverse flora and fauna. The English word karst, used generically for this type of topography, derives from this region.

Half of the country (about 58%) is covered by forests. These forests are an important natural resource, but they are also valuable for the preservation of natural diversity. An ecological asset like all forests, they enrich the soil and cleanse the water and air. Slovenians find the social benefits of tourism and recreation. The forests also lend their natural beauty to the Slovenian landscape. In the interior of the country there are typical Central European forests. The predominant trees are oaks and beeches. In the mountains, spruce, fir, and pine are more common. The tree-line is at 1,700 to 1,800 metres (or 5,575 to 5,900 feet).

Pinetrees also grow on the Karst plateau. Only one third of Kras (Karst) is now covered by pine forest. It is said that most of the forest was chopped down long ago to provide the wooden pylons on which the city of Venice now stands. The Karst and White Carniola are well known for the mysterious proteus. The lime/linden tree, also common in Slovenian forests, is a national symbol. In the Alps, flowers such as Daphne blagayana, various gentians (Gentiana clusii, Gentiana froelichi), Primula auricula, Edelweiss (the symbol of Slovenian mountaineering), Cypripedium calceolus, Fritillaria meleagris (Snakes’s head), and Pulsatilla grandis are found.

The country’s fauna includes marmots (introduced), steinbocks, and chamois. There are numerous deer, roe deer, boars, and hares. The edible dormouse is often found in the Slovenian beech forests. Hunting these animals is a long tradition and is well described in the book The Glory of the Duchy of Carniola (Slava vojvodine Kranjske) (1689), written by Janez Vajkard Valvasor (1641-1693). Some important carnivores include the Eurasian lynx (reintroduced to the Kočevje area in 1973), European wild cats, foxes (especially the red fox), and the rare jackal. There are also hedgehogs, martens, and snakes such as vipers and grass snakes. As of March 2005, Slovenia also has a limited population of wolves and around four hundred brown bears.

There is a wide variety of birds, such as the tawny owl, the long-eared owl, the Eagle Owl, hawks, and Short-toed Eagles. Various other birds of prey have been recorded, as well as a growing number of ravens, crows and magpies migrating into Ljubljana and Maribor where they thrive. Other birds include (both black and green) woodpeckers and the white stork which nests in Prekmurje. The indigenous Slovenian fish is the Marmorata, a type of trout. Extensive breeding programs have been introduced to repopulate the Marmorata into lakes and streams invaded by non-indigenous species of trout. The only regular species of cetaceans found in the northern Adriatic sea is the Bottlenose Dolphin (Tursiops truncatus).

Domestic animals originating in Slovenia include the Carniolan honeybee, the indigenous Karst Sheepdog and the Lipizzan horse. The exploration of various cave systems has yielded discoveries of many cave-dwelling insects and other organisms. Slovenia is a veritable cornucopia of forest, cavern and mountain-dwelling wildlife. Many species that are endangered or can no longer be found in other parts of Europe can still be found here.