The soils of the Ituri Forest developed from granites, gneisses, and metamorphosed rock of Precambrian age. In most places the soil is sandy clay or sandy clay loam, ranging in colour from reddish brown through ochre to yellowish brown and even white. The soils are acidic, and the layer of humus is thin. If exposed to the strong equatorial sun and high rainfall, as when the forest vegetation is cleared by Bantu farmers, the soil deteriorates rapidly, recovering only if it is again taken over by secondary forest. Traditionally, farmers have practiced shifting cultivation to allow the fragile soils to regenerate.

Plant and animal life

The climax-forest vegetation left undisturbed by human occupation is characterized by three dominant species of tall, hardwood legumes in the subfamily Caesalpinioideae. In the south and west Gilbertiodendron deweverei dominates and can constitute 90 percent of the standing vegetation. The regions of the forest dominated by only a few plant species have less abundant and diverse animal life than the other, more botanically mixed areas, such as in the north and east. There, Cynometra alexandrii and Brachystegia laurentii, which together comprise less than 40 percent of the canopy, are interspersed with numerous other tall species (e.g., Albizia, Celtis, and Ficus).

For many generations, people residing in the Ituri have been practicing a form of agriculture that entails clearing and burning the forest, growing their crops, and then moving after several years to allow the forest to regenerate during a long fallow period. This method of shifting slash-and-burn cultivation has created a patchwork of climax vegetation interspersed with various successional stages of secondary forest on the sites of old gardens and abandoned villages. Some areas are a tangle of lianas and shrubs beneath emerging hardwood trees, while others are in less-advanced stages of succession, with large stands of umbrella trees (Musanga cecropoides). These various seral patches—combined with river valleys, swampy waters, rock outcroppings, and the most recent village and garden clearings near the roads—produce a mosaic of diverse habitats that provide cover and food for the greatest abundance of mammals in forested Africa.

Situated near the forest-savanna edge, Ituri fauna include not only species typical of the African equatorial forest but also forms, such as the hyena, that are usually found on the open savanna. The most notable species is the forest giraffe, called okapi, which is endemic to the Ituri. Numerous forest antelopes include five species of duiker, the water chevrotain, and the pygmy antelope. Leopards, genets, and mongooses are the main carnivores. The elephant, buffalo, and bongo (a kind of antelope) are present in forms slightly smaller than their savanna relatives. The Ituri also supports the greatest diversity of primates of any comparable area in the world. The many monkeys include the terrestrial anubis baboon, as well as the leaf-eating imperial black and white colobus and the owl-faced monkey. The only ape is the chimpanzee. Hundreds of species of birds have been recorded; among them, the shy Congo peacock, discovered in 1936, is perhaps the most famous.

Efforts to preserve the fauna and flora are largely confined to the Maiko National Park on the southern edge of the Ituri and the Okapi Wildlife Reserve (designated a UNESCO World Heritage site in 1996) to the northeast. Both offer some protection for such animals as the forest elephant, the okapi, the Congo peacock, the aardvark, and the chimpanzee, but poaching activities and destruction of forest habitat seriously threaten these and other species both outside and inside the park. Conservation efforts have also been disrupted by civil strife that began in the late 1990s and continued into the 21st century.