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Variants

See also: Tropical ecology and Tropical climate

The term 'Tropical vegetation' is frequently used in the sense of lush and luxuriant, but not all the vegetation of the areas of the Earth under a tropical climate could be adequately defined as such. Despite their lush appearance, often the soils of tropical forests are low in nutrient content making them quite vulnerable to slash-and-burn deforestation techniques, which are sometimes an element of shifting cultivation agricultural systems. Tropical vegetation may include the following habitat types:

Tropical rainforest

Tropical rainforest ecosystems include significant areas of biodiversity, often coupled with high species endemism. Rainforests are home to half of all the living animal and plant species on the planet and roughly two-thirds of all flowering plants can be found in rainforests. The most representative are the Borneo rainforest, one of the oldest rainforests in the world, the Brazilian and Venezuelan Amazon Rainforest, as well as the eastern Costa Rican rainforests.

This is the most complex and extensive type of vegetation in the humid tropics. The rainforest occupies approximately 10% of the world's surface. It has three significant formations namely the African, the American and the Indo-Malaysian. The American covers the Orinoco and the Amazon basins and is the largest of the remaining tropical forest areas. The African is categorized into two major parts, along with the Guinea Coast and the Congo basin. Approximately, 90% of flowering plant species are evergreen trees and 50% are eight to thirty meters tall. The evergreen trees have shallow root systems, smooth bark, and slender trunks and have simple leaves. The canopy consists of trees of middle and upper layers ranging from 20-30 meters.

Tropical seasonal forest

Seasonal tropical forests generally receive high total rainfall, averaging more than 1000 mm per year, but with a distinct dry season. They include: the Congolian forests, a broad belt of highland tropical moist broadleaf forest which extends across the basin of the Congo River; Central American tropical forests in Panama and Nicaragua; the seasonal forests that predominate across much the Indian subcontinent, Indochina and in northern Australia: Queensland.

The seasonal forests and woodlands are divided into three namely the deciduous forest, thorn woodland, and semi-evergreen forest. Semi-evergreen seasonal forests exist in the American tropics, and deciduous, and evergreen trees dominate them. Trees are less tall, lack buttresses, form annual growth rings, flower in dry seasons and have thicker bark compared to the rainforests. The seasonal deciduous forests are in Africa, Indo-Malaysia, and American tropics. Deciduous trees are dominant in this forest, and they have plate-like crowns and have an umbrella shape. Thorn woodland is part of the American tropics where they are found in large numbers. In areas where it is developed, it includes evergreen trees and succulents. The small leaves are reduced to scales and thorns that mitigate the loss of water by transpiration.

Tropical dry broadleaf forest

Tropical dry broadleaf forests are territories with a forest cover that is not very dense and has often an unkempt, irregular appearance, especially in the dry season. This type of forests often include bamboo and teak as the dominant large tree species, such as in the Phi Pan Nam Range, part of the Central Indochina dry forests. They are affected by often very long and intense seasonal dry periods and, though less biologically diverse than rainforests, tropical dry forests are home to a wide variety of wildlife.

Tropical grasslands, savannas, and shrublands

Tropical grasslands, savannas, and shrublands are spread over a large area of the tropics with a vegetation made up mainly of low shrubs and grasses, often including sclerophyll species. Some of the most representative are the Western Zambezian grasslands in Zambia and Angola, as well as the Einasleigh upland savanna in Australia. Tree species such as Acacia and baobab may be present in these ecosystems depending from the region.

When there is lengthening of the dry season to around eight months, savannas and woodlands pave the way for the desert shrub vegetation. There are unique formations in South and North America, mainly in the Atacama and Sonora deserts. Succulents and shrubs having extensive root systems are the most conspicuous characteristic of the climatic zone. The plants and shrubs can survive increased aridity by minimizing transpiration for xerophytes. The succulents also reduce transpiration by trapping the supplies in the moisture. The ground is rarely entirely covered by vegetation apart from the seasonal watercourses. Individual plants are spaced widely. There is low floristic diversity compared to the rainforests.

Characteristics

The studies of ecology in the tropical environment still need to be studied in greater depth and because of its complexity, it is the least understood ecosystem in the world. The vegetations in the tropical environment have inherited traits that help them to better survive in their environment. Through the process of evolution, plants evolve to be more physically adapted the tropical climate.

Soil

The soil condition of the tropical climate is very unique because it is affected by natural factors, for example, by the ocean, animals, sediments and decomposing minerals. The kaolinite (clay) soil is often found in the tropical regions. They have large phospholipid pockets within the soil that are bonded tightly, which made the soil into excellent drainage and resistant to expansion when absorbing water. Different from the wet and sticky soil in the temperate region, the kaolinite clay have firm structure.