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Populus euphratica, also known as Hutong, is a deciduous tree of Salicaceae.
The height of the tree is1.5 ~ 30m, and seedlings can sprout from the roots. Can endure the drought in the desert, and has strong saline-alkali tolerance. The root of Populus euphratica can be tied underground 10 meter to absorb water, and its cells have special functions and are not damaged by alkaline water. Populus euphratica is an ancient Mediterranean component, an ancient tree species left over from the third century, which survived on the earth more than 60 million years ago. Appeared in the ancient Mediterranean coastal areas one after another and became an important part of the valley lobular forest. In the early and middle Quaternary, Populus euphratica gradually evolved into the most important constructive species of desert riparian forest. Mainly distributed in southern Xinjiang, western Qaidam Basin, Hexi Corridor and other places.
According to statistics, the vast majority of Populus euphratica in the world grows in China, while more than 90% of Populus euphratica in China grows in Tarim River Basin in Xinjiang. At present, the Populus euphratica Forest Reserve, which is considered to be the oldest, largest, most intact and primitive in the world, is located in luntai county.
Morphological characteristics of (1)
Deciduous trees, up to 30 meters, DBH can reach 1.5 meters; The bark is grayish brown with irregular longitudinal cracks. Leaves on long branches, seedlings and young trees are linear-lanceolate or narrowly lanceolate, 5~ 12 cm long, entire, tapering at the top and cuneate at the base; The leaves on the short branches are oval rhombic, round to kidney-shaped, 25 cm long and 3 cm wide, with 2~4 pairs of wedge-shaped coarse teeth at the top, truncated at the base, sparsely nearly heart-shaped or wide wedge-shaped; Petiole length 1~3 cm, smooth, slightly flat, dioecious, rhombic; Bracts rhombic, upper part usually serrate, caducous; Male inflorescence is1.5 ~ 2.5cm long, with 23~27 stamens, pedunculate and purple anthers; The female inflorescence is 3~5 cm long, the ovary is stalked, the stigma is wide and purple; The ear length is 6~ 10 cm. The germinated fruit is oval, long 10~ 15 mm, 2-split, with short fluff at the beginning and smooth back.
(2) Features
Populus euphratica is a typical mesophyte in the desert area of Asia and Africa, which has been adapted to the extremely arid continental climate for a long time. Strong adaptability to large temperature changes, like light, like soil moisture, atmospheric drought resistance, high temperature and cold resistance; It is suitable for the warm temperate desert climate above 65,438+00℃, and the accumulated temperature is between 2,000℃ and 4,500℃. It is most suitable for growing along warm temperate desert rivers and on the fine sandy soil of floodplain with accumulated temperature above 4,000℃. It can withstand the extreme maximum temperature of 45℃ and the extreme minimum temperature of -40℃. Populus euphratica has strong saline-alkali tolerance, and grows well when the total soil salt content is below 1% in the range of1m. When the total salt content is 2 ~ 3%, the growth is inhibited; When the total salt content exceeds 3%, it dies in pieces. Flowering in May and fruiting in June-July.
(3) Protecting value
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Populus euphratica is a unique and precious forest resource in desert areas. It plays a very important role in stabilizing ecological balance, preventing wind and fixing sand, regulating oasis climate and forming fertile forest soil in desert rivers. It is a natural barrier for developing agriculture and animal husbandry in desert areas. At the same time, Populus euphratica is an ancient tree species, which is of great scientific value to the study of climate change, river change, flora evolution and ancient economic and cultural development in desert areas of Asia and Africa.
(4) Protective measures
Rationally adjust the relationship between agriculture, animal husbandry and forestry in arid desert areas and prohibit deforestation; The reservoirs in the upper reaches of the river should regularly release water to the middle and lower reaches to ensure the restoration and development of Populus euphratica forest. At the same time, two Populus euphratica nature reserves will be established in northwest China as scientific research and species protection bases.
(5) key points of cultivation
Reproduce with seeds. The seeds of Populus euphratica are easy to lose germination ability due to water loss. In July and August, the ear turns from green to yellow, and the top of the capsule cracks, revealing white flocs. After that, excellent mother plants should be selected in time, and the ear should be collected, dried and seeded. Choose moist, fertile and well-drained fine sand or sandy loam to build a bed, a ridge bed or a low bed, and drill or sow the seeds after mixing them with fine sand. 2~4 years old seedlings can be planted. Afforestation can use direct seeding or planting seedlings. Populus euphratica in Xinjiang is the most widely distributed area in China and even in the world. It is said that 90% of the world is in China and 90% of Populus euphratica in China is in Tarim Basin. The area of Populus euphratica Reserve in Tarim Basin alone is 3,800 square kilometers. There are also scattered patches in Junggar basin in northern Xinjiang. Populus euphratica is the only tree species that lives in the desert, and it has witnessed the process of desertification in the arid area of northwest China from beginning to end. Now, although it has retreated to the river bank of the desert, it is still the soul of life in the desert called "the sea of death". Populus euphratica was widely distributed in temperate and warm temperate regions in western China. Fossils of Populus euphratica were found in Qianfo Cave, Kuqa, Xinjiang, Tiejianggou, Dunhuang, Gansu and Ping Long, Shanxi, which proved that it was a tertiary residual plant more than 65 million years ago. Nowadays, in addition to the Qaidam Basin, Hexi Corridor and Alashan in Inner Mongolia, a small amount of Populus euphratica can be seen on both sides of some rivers flowing into the desert. More than 90% of Populus euphratica forests in China are curled up in Xinjiang, and 90% of them are concentrated in Tarim Basin, which is called "extremely arid desert" in southern Xinjiang. Although Populus euphratica grows in extremely arid desert areas, its bones are full of thirst for water. Although it has made many changes to adapt to the arid environment, such as leathery leaves, long hair on branches, and even young leaves such as willow leaves to reduce the evaporation of water, it is known as "Populus heterophylla". However, as a big tree, it still needs corresponding water to survive. Therefore, ecotype is mesophyte, which is an intermediate type between aquatic and xerophyte. So where does it need water? It turned out to be a plant with water. Where the desert river goes, it follows. The rivers in the desert change quite frequently, so Populus euphratica leaves stops everywhere in the desert. Relying on the protection of root system, it can still live very comfortably as long as the groundwater level is not less than 4 meters; After the groundwater level drops to 6~9 meters, it can only be cheerful and unhappy; If the groundwater level is lower, it will have to say goodbye to the world. Therefore, as long as you see rows of Populus euphratica, fresh or dry, you can judge that there was water flowing here. Because of this, some people call Hu Yang an "irresponsible mother". It leaves its descendants everywhere, regardless of their lives. In fact, this is also a kind of helplessness to environmental constraints. Populus euphratica in Tarim basin, especially along Tarim River, is the largest distribution area of Populus euphratica on the earth, which was once very brilliant. In the Western Han Dynasty, the coverage rate of Populus euphratica in Loulan was at least above 40%, and people depended on it for food, clothing, housing and transportation. By the Qing Dynasty, "Hutong (Populus euphratica) was still everywhere and became a deep forest." However, in the short period of 20 years from the mid-1950s to the mid-1970s, the area of Populus euphratica forest in Tarim Basin decreased sharply from 520,000 hectares to 350,000 hectares, a decrease of nearly one third. In the lower reaches of Tarim River, Populus euphratica forest has decreased by 70%. Among the surviving forests, declining forests account for a considerable part. The main reason for this result is the unreasonable social and economic activities of human beings. The disappearance of Populus euphratica and its undergrowth plants has made the middle and lower reaches of Tarim River one of the two major sources of sandstorms in Xinjiang. Fortunately, people learned from setbacks and began to save Tarim River and Populus euphratica forest. The emergency water delivery in the lower reaches of Tarim River has achieved initial results, and the Populus euphratica forests on both sides of the river have begun to recover. The Tarim Populus euphratica Forest Reserve with an area of nearly 390,000 hectares has been upgraded to a national nature reserve. Luntai Populus euphratica Park has also been upgraded to a national forest park; The wetland in the middle reaches of Tarim River, which is dominated by Populus euphratica forest land, has attracted the attention of international organizations and is listed as the key protection object. Populus euphratica, who received such high-standard courtesy from human beings for the first time, will certainly live up to human kindness and will definitely show the glory of history again! Heihe River, which originated in Qilian Mountain, is the largest river in Hexi Corridor of Gansu Province, and was called weak water in ancient times. Its downstream flows into Ejina in western Inner Mongolia and into Juyan Sea. Juyanhai, located about 400 kilometers north of Jiuquan, Gansu Province, was known as "Juyanhai Granary" from the Western Han Dynasty to the Song and Yuan Dynasties. Counties or military departments were set up in Juyanhai area throughout the dynasties. Xixia built the famous Black City on the ruins of the city wall, which was once a prosperous transportation hub on the Silk Road. 13rd century Kyle "When the Yuan Dynasty Polo went to Dadu Road and passed through Black City, it was still a place with" abundant water resources, dense pine forests, wild donkeys and all kinds of wild animals frequented ",and it was a fertile land for agriculture and animal husbandry. Until the 1940s, Juyanhai still had more than 300 square kilometers of lake surface, surrounded by Heihe River and Beida River to Ejina, forming a fan-shaped forest belt on the flat and vast Gobi Desert. This forest belt extends from Tiancang Township in Jinta County, Gansu Province to Juyan River in Ejina, with a length of about 200 kilometers and a width of 15 kilometers, forming a "grasshopper reed". After the 1960s, 30 reservoirs with a million cubic meters or more were built in the whole basin, among which Qijiadian, Ying Ge Zui, Qinghe Bay, Yuanyangchi, Jiefang Village and Heishan Lake were larger in scale. Finally, the whole Heishui River was basically sucked dry, so that the downstream was cut off; In addition, the precipitation is less, the youngest is only a dozen millimeters, the evaporation is as high as 4000 millimeters, the Juyan Sea dries up, and 850,000 mu of natural vegetation such as Populus euphratica, Salix, Hippophae rhamnoides rot and die. It is still decreasing at a rate of 50,000 to 70,000 plants per year, and 50 million mu of grassland is desertified. Groups of farmers and herdsmen had to move their families and become ecological refugees.
1April, 1998, a sandstorm from Ejina swept through Beijing, Jinan and Xuzhou, and reached Nanjing directly. The source of this dust comes from the Alashan Plateau in the north. When this oasis dies, the next victims under the sandstorm are Hexi Corridor and Hetao Plain. For example, Bashang Plateau in northern Hebei and Hunshandake Sandy Land in central Inner Mongolia. By comparing two sets of Landsat images, we can clearly see that the dark green representing forests and grasslands is shrinking sharply, while the yellow quicksand is expanding rudely. According to the analysis of satellite photos of Weichang County in Hebei Province and Duolun County in Inner Mongolia 1987 and 1996, the area of quicksand increased from 68,000 hectares to 129 and 100 hectares in 9 years, with an increase of 89.9%, and the forest area decreased from 363,500 hectares to 222,400 hectares. The situation in Hunshandake Sandy Land is also not optimistic. According to the analysis of satellite photos of 1989 and 1996, the area of quicksand increased from 185500 hectares to 358600 hectares, an increase of 93.3%, while the area of grassland decreased from 602500 hectares to 43000 hectares, a decrease of 28.6%. Tarim Basin is the most widely distributed desert area in China, and it is also the area with the richest desert heat resources in China. In the desert, quicksand is absolutely dominant, accounting for about 85% of the desert. There are natural vegetation belts dominated by Populus euphratica and Salix, which form natural oases in the desert along the Tarim River and in the front of alluvial fans at the edge of the desert. This is the largest natural Populus euphratica forest in the world, with a total area of 352,000 hectares. It is mainly distributed around the Taklimakan desert, like a green Great Wall, which tightly locks the expansion of mobile sand dunes. At the same time, Populus euphratica forest is also an excellent four-season pasture and wildlife habitat. Due to the decrease of water in the lower reaches of Tarim River, hundreds of miles of Populus euphratica forest collapsed due to thirst. Although Populus euphratica has a strong vitality, "it will not die in a thousand years, it will not fall in a thousand years, and it will not fall in a thousand years." But it cannot escape the long-term waterless disaster. Populus euphratica can't live for a hundred years in this Millennium, and tears are exhausted.
In recent years, the water transport capacity of the source and main stream of Tarim River has shown an obvious downward trend. Populus euphratica died in a large area. The area of Populus euphratica forest in the middle and lower reaches of Tahe River reached 5.8 million mu in 1950s, 2.97 million mu in 1970s and only 1.525 million mu in 1990s. In the past 40 years, it has decreased by half every 20 years and nearly 3/4. The reduction of Populus euphratica forest area has also led to the continuous reduction of wild animals living in forest areas. In the 1970s, a small number of wild animals such as red deer were found in Populus euphratica forest area, and now they have basically disappeared.
The green corridor downstream is on the verge of destruction. From the 1960s to the early 1980s, the desertification in the middle reaches of the Tahe River has been expanding. The downstream area is the most seriously desertification area. During the 20 years from 1958 to 1978, the proportion of desertified land in this area has increased from 12% to 52%, and new sand dunes have been formed continuously, and the green corridor is in danger of disappearing.
According to the satellite remote sensing survey of the office of the National Agriculture Department of China, during the period from 1986 to 1996, Heilongjiang, Inner Mongolia, Gansu and Xinjiang provinces * * * reclaimed1940,000 hectares of land, while the reserved area was only 986,000 hectares, half of which was abandoned, that is, desertification. Comprehensive monitoring by authoritative departments shows that during the 25 years since 1950s, the area of desertified land in China has expanded by 65,438 0.56 square kilometers every year, and by the early 1980s, the expansion speed has accelerated to 265,438 0.000 square kilometers every year. According to the results of the national desertification survey in 1994, the rate of desertification has reached 2460 square kilometers per year, and the area of desertified land in China is close to1700,000 square kilometers, accounting for 18% of the national territory, and most of them are concentrated in the west. In Houshan of Inner Mongolia, Alashan, the lower reaches of Tarim River in Xinjiang, the southeast of Qaidam Basin in Qinghai, Bashang of Hebei and Naqu of Tibet, the average expansion rate of sandy land is above 4%. There have been several famous ancient cities (such as Karatun, Gyeonggi, Loulan, Heicheng, Juyan and Wantong) in the sand area in history. ) to reflect the changes in deserts since human history. On April 5th, 2006, Populus euphratica growing area in Tarim, Xinjiang was approved as a national nature reserve by the State Council. People praise Populus euphratica like this: hold your head high for a thousand years, stand upright for a thousand years after death, fall into immortality for a thousand years, cast iron bones for a thousand years, and praise unyielding quality for a thousand years.
(6) Populus euphratica landscape
Populus euphratica landscape is listed as one of the top ten wonders in China.
Features: Go deep into the desert and feel the vitality of Populus euphratica.
Wonderful attractions: Ejina Banner, Inner Mongolia: The location of the movie Hero is divided into two parts: Populus euphratica and Strange Forest.