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Asian plants, which include ferns, gymnosperms, and flowering vascular plants, make up 40 percent of the earth's plant species. The endemic plant species come from more than forty plant families and fifteen hundred genera. Asia is divided into five major vegetation regions based on the richness and types of each region's flora: tropical rain forests in Southeast Asia, temperate mixed forests in East Asia, tropical rain dry forests in South Asia, desert and steppe in Central and West Asia, and taiga and tundra in North Asia.
Tropical Rain Forests
The Asian regions richest in flora, tropical rain forests, are found in the island nations of Southeast Asia, which extend from Kinabalu in the north to Java in the south and from New Guinea in the east to Sumatra in the west. In this vast archipelago, the longest island chain between Asia and Australia, are thirty-five thousand to forty thousand vascular plant species. Tropical rain forests grow there year-round because of the region's warm temperatures and plentiful rainfall. The forests contain great varieties of tall trees, some towering 148 feet (45 meters) high. Within any 1-square-mile area, one can see as many as one hundred tree species with no single species dominant.
The rain forests have mostly broad leafed ever greens, with some palm trees and tree ferns. The uppermost branches of the trees form canopies that cover and protect the earth below. Because little sunlight penetrates the dense canopies, few shrubs or herbs grow in the rain forests. Instead, many vines, lianas, epiphytes, andparasites are twined on tree branches and trunks. Mangroves fringe the tropical rain forests along the coasts.
Temperate Mixed Forests
Second in floral richness, East Asia's temperate mixed forests contain thirty thousand to thirty-five thousand plant species. This region ranges from Japan in the east to the Himalayan nations (Bhutan, Sikkim, and Nepal) in the west, and from Russia's Amur River Valley in the north to China's Hainan Island in the south. East Asia's temperate weather is similar to the climate of eastern North America, with hot summers and cool winters. From south to north and from the east coasts to lower elevations in mountainous areas in the west, the vegetation changes from evergreen to deciduous broad-leafed forests, with dense shrubs, bamboo, and herbs in different layers beneath the forest canopy. The major tree species are of the magnolia, oak, tea, laurel, spurge, azalea, and maple families. Herbs include members of the primrose, gentiana, pea, carrot, foxglove, composite, buttercup, and rose families.
The Himalayan range is the point where the regions of South Asia, East Asia, and Central and West Asia join. From the Qinghai-Tibet Plateau in southwest China to the lower areas of the Himalayas, elevation usually is between about 5,000 and 13,000 feet (1,500 and 4,000 meters). Mountains with deep valleys showcase complex, multiple vegetation types from mixed forests and dense shrubs to alpine meadows in mountain plains. Many primary seed plants (gymnosperms and flowering plants), grow there.
Untouched native vegetation in East Asia is usually found only in mountainous or remote areas. On mountains at high elevations, the points where the temperatures are so cold that trees cannot grow form what is called the tree line. Near the tree line, only plants related to coniferous and alpine species grow. Above about 13,000 feet (4,000 meters) in high mountain areas, no vegetation grows. Instead, snowcaps or icebergs exist year round.
Tropical Rain / Dry Mixed Forests
The thirdrichest region, tropical rain/dry forests, is found in South Asia, which reaches from the Philippines in the east to Pakistan in the west, and from the Himalayas in the north to Thailand in the south.
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Desert and Steppe
The desert and steppe region in Central and West Asia has twenty to twenty-five thousand species of plants.
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Taiga and Tundra
The poorest region in floral richness, with only about five thousand vascular plant species, is North Asia.
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Food Crops
The poorest region in floral richness, with only about five thousand vascular plant species, is North Asia.
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Scientific Value
The poorest region in floral richness, with only about five thousand vascular plant species, is North Asia.
Continue of the article: Scientific Value
See also: Asian agriculture
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