Rainforests are very dense, warm, wet forests. They are havens for millions of plants and animals.
Rainforests are extremely important in the ecology of the Earth. The plants of the rainforest generate much of the Earth's oxygen. These plants are also very important to people in other ways; many are used in new drugs that fight disease and illness.
tropical rain forest
Lush forest, generally composed of tall, broad-leaved trees and usually found in wet tropical regions around the Equator.
Despite increased awareness of the rainforests' importance during the late 20th century, they continue to be cleared. Rainforests grow mainly in South and Central America, West and Central Africa, Indonesia, parts of Southeast Asia, and tropical Australia, where the climate is relatively humid with no marked seasonal variation. Depending on the amount of annual rainfall, the trees may be evergreen or mainly deciduous. The former require more water. Temperatures are high, usually about 86 °F (30 °C) during the day and 68 °F (20 °C) at night. Soil conditions vary with location and climate, though most rainforest soils tend to be permanently moist and not very fertile, because the hot, humid weather causes organic matter to decompose rapidly and to be absorbed quickly by tree roots and fungi. Rainforests have several layers. The highest continuous layer, called the canopy, extends across the treetops at a height of 100–165 ft (30–50 m). Most animals live among the leaves and branches. Below the canopy is a thick understory filled with small trees, lianas, and epiphytes. The space directly above the ground can be occupied by tree branches, twigs, and foliage, but, contrary to popular belief, the rainforest floor is not impassable. Rather, it is bare except for a thin layer of humus and fallen leaves. Animals inhabiting this layer (e.g., gorillas, elephants, jaguars, and bears) are adapted to walking or climbing for only short distances. Burrowing animals, such as armadillos and caecilians, are found in the soil, as are microorganisms that help decompose and recycle the organic litter accumulated by other plants and animals from all layers. The climate of the ground layer is unusually stable because the upper stories of tree canopies and the lower branches filter out sunlight, retain heat, and reduce wind speeds, keeping the temperature fairly even.
The amazon river water discharge from the Atlantic to 18 million per 1000 cubic meters, equivalent to around four rivers to the Marine discharge all the total freshwater one-fifth of the amazon river, until the coast of invisible, the water is not salty sea, 150 kilometers of seawater salinity is outside. Amazon ZhuHeDao has 1.5 to 12 km wide, from the river to the inland waterway there 3700miles, ships can directly to Peru, a small boat can continue to sail 780 kilometers, library's Angle, again small boat can keep up. The amazon basin area reaches 6915000 square kilometers, equivalent to South America, north latitude 40 per cent of total 5 degrees from 20 degrees, stretching to the great source in the andes, from the ocean in the plateau is only a short distance, Peru and Brazil at the equator into the Atlantic ocean.
1. Tropical forests provide human beings with oxygen and are home to wild animals.
2. In recent years the areas of tropical forests are declining as a result of destruction, which pose a serious threat to the survival of the wild animals.
3. We call on the goverment to make laws to protect tropical forests. Middle students also can take actions to protect the forests.
望采纳,还要兑现诺言追加