Oxisols , infertile, deeply weathered and severely leached, have developed on the ancient Gondwanan shields. Rapid bacterial decay prevents the accumulation of humus. On younger substrates, especially of volcanic origin, tropical soils may be quite fertile. Jungles may line rivers where sunlight penetrates all layers of the forest. Where forests have long been cleared and laterites have developed to cause season waterlogging of the sub strate, tropical grasslands and palm savannas occur.
Animal life is highly diverse.
The species composition and even genera and families are distinct in each. They also differ from species of temperate forests. Where 5 to a maximum of 30 species of tree share dominance in the Temperate Broadleaf Deciduous Forest, there may be 40 to 100 different species in one hectare of tropical rainforest. Tropical species of both plants and animals often hav e very restricted distribution areas. Distinct communities are found at higher elevations, communities that do not replicate latitudinal changes in vegetation as do alpine communities in temperate zones.