Tropical rain forest refers to a cool, humid and rainy area with high temperature, inconspicuous structural level and rich plants outside the layer.
bivariate distribution
Most tropical rainforests lie between 23.5 degrees north latitude and 23.5 degrees south latitude. It is distributed in all three tropical regions of the world. The largest area is in the United States. At present, 40,000 square kilometers are still preserved in the Amazon river basin in South America, accounting for about half of the total tropical rain forest area, that is, about 1/6 of the total global broad-leaved forest area. The second largest area is the rainforest in tropical Asia, covering an area of 20,000 square kilometers. The third largest area is the Congo Basin rainforest in tropical Africa, with an area of 1.8 million square kilometers. Are formed in the rainforest climate near the equator. Rainforests along the east coast of Central America and the West Indies, northeast Australia, east coast of Madagascar and southeast Brazil are developed in tropical maritime climate.
It is also distributed in Yunnan, Taiwan Province and Hainan.
Third, the rainforest ecology
Tropical rain forest is a lush forest type. Entering the forest, you seem to be in a mythical world. Looking up here, I can't see the blue sky, and my head is covered with moss. The impenetrable forest in the tropical rain forest is humid and sultry, and my feet are slippery everywhere. It is not only difficult but also dangerous for people to walk in dim light and places infested with insects and snakes. However, it is a paradise for creatures, both animals and plants, which are incomparable elsewhere on land.
In areas where tropical rainforests are distributed, the annual rainfall is very large, usually higher than 1800 mm, and in some places it reaches 3500 mm There is no obvious seasonal change here. The temperature is generally around 30 degrees Celsius during the day and around 20 degrees Celsius at night.
The topography of the rainforest area is complex and diverse, from the lowland plain scattered with rocky hills to the plateau canyon crisscrossed with streams. A variety of landforms have created a variety of rainforest landscapes. In the forest, quiet pools, swift streams and waterfalls can be seen everywhere; Towering trees, winding vines and lush flowers interweave into a green maze.
There are many kinds of plants in tropical rain forest, among which trees have multi-layer structure; The upper trees are more than 30 meters high, mostly typical tropical evergreen trees and deciduous broad-leaved trees. The bark is light, thin and smooth, and there are often plate roots at the base of the tree, and flowers can grow on the old trunk. Woody vines and epiphytes are particularly developed, with some mosses and lichens attached to the leaves, and woody ferns and big-leaved herbs under the forest.
The trees in the rainforest are mostly dicotyledonous plants with thick leathery leaves and shallow roots. Roots for nutrition are usually only a few centimeters deep. Rainfall in the rain forest is greatly lost due to evaporation of leaves. The soil and rocks in tropical rain forest are strongly weathered, and its weathering crust can reach 100 m. Although this soil is rich in aluminum, iron oxide, hydroxide and kaolinite, some other minerals will be lost by leaching and erosion. In addition, under the condition of high temperature and high humidity, organic matter decomposes quickly and can be quickly absorbed by hungry roots and fungi. Therefore, the soil here is actually not fertile.
The sub-canopy plants in the rainforest are composed of small trees, lianas and epiphytes, such as Orchidaceae, Bromeliaceae and ferns. Some plants are epiphytes, twining around the trunk of parasitic tropical rain forest, while others only use trees as support. The surface of the rainforest is covered with branches and fallen leaves. The ground in the rainforest is not impassable as the legend says. Most of the ground is bare except for the thin humus layer and fallen leaves.
In the rainforest, woody vines can be seen everywhere, some as high as twenty or thirty centimeters, and some as long as 300 meters. They climbed from tree to tree along the trunk and branches, climbed from tree to tree top, hung upside down from the tree top, and intertwined like dense nets. Epiphytes, such as algae, mosses, lichens, ferns and orchids, are attached to the trunks and branches of trees, shrubs or vines, just like wearing a thick green coat. Some of them produce all kinds of gorgeous flowers, and some even attach to leaves, forming a wonderful scenery of "trees on trees" and "grass on leaves".
Fourth, the typical representative of tropical rain forest.
The tropical evergreen rainforest in the Amazon Plain is not only the most extensive in the world, but also the most fully developed and typical. This is due to the geographical location and topographical structure of the Amazon Plain, which has modern climatic conditions that are particularly conducive to this type of development. On the other hand, it has a long history of development and relatively stable natural geographical conditions during its formation. The tropical evergreen rainforest in South America, also known as Hillea community, is extremely rich in plant species and mixed with each other, and rarely forms pure forests, one third of which are endemic to South America. They keep growing, and plants flourish all year round. Trees, shrubs, herbs, vines and epiphytes constitute a multi-level closed jungle. Generally, there are 4 to 5 floors, many of which can reach 1 1 to 12 floors, and the Crown City is uneven. In order to get sunlight, many trees try to grow upward, and their trunks rarely branch, and some can reach 80 to 100 meters.
Verb (abbreviation for verb) is typical of soil and animals.
Typical soils developed under tropical evergreen rain forest are latosol and red soil with ashing phenomenon. The former is distributed in areas with high terrain, good drainage and little rainy season, while the latter is mainly distributed in areas with abundant precipitation, closed forests and lack of herbaceous vegetation in each season.
There are many animals in the rainforest, but they are mainly small arboreal animals. Another feature is that there are many kinds and few individuals. Especially the insects in the rain forest, it is much easier to find a hundred kinds of insects than to find a hundred kinds of the same kind. Scientists believe that many rainforest insects have not been known to us so far.
Elephants, hippos and other large animals generally only live on the edge of the rainforest or in slightly open valley areas.