The mountainous regions of Tonkin, as well as the Annam Cordillera, are characterized by tropical rain forest broken by large areas of monsoon forest. In the higher altitudes of the far northwest there are pine forests. Shifting cultivation has resulted in many sections of secondary forest. Tropical grasses are widespread, and there are mangrove forests fringing parts of the Red River Delta and in the Ca Mau peninsula, which juts into the Gulf of Thailand. Tropical evergreen forests predominate in the south, with extensive savanna in the southwest.
Deer and wild oxen are found in the more mountainous areas. There are many species of tropical birds and insects.