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Poplar's ancestors appeared 135 million years ago and are the oldest rare tree species in the world. 65 million years ago, poplar gradually became the most important group tree species in the northwest riverbank forest of China. Poplar has repeatedly migrated with the diversion of rivers to desertification, and the traces of its stops have witnessed the process of desertification in northwest China. Today, poplar forests are still like green walls locking the expansion of the desert. Poplar has ecological, scientific, economic, medical and aesthetic values. The colorful feast of the original poplar forest in autumn flashes the splendor of generational struggles with the drought and desert and the splendor of strain, giving people a shock that touches the heart.
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Populus, populaceae, populaceae, is a tall, deciduous natural tree. Poplar belongs to the poplar school, one of the five schools of poplar trees, and is the oldest species in the poplar genus. The tree is 15-30 meters tall and generally 100-300 years old. China's poplar is distributed in the desert Gobi belt in the northwest region. Populus interacts with the arid and saline environment in which it lives to form special biological properties. Its roots, leaves, branches, cells, reproduction, etc. change, suitable for sandy soil growth, drought tolerance, salinity tolerance, cold tolerance, heat resistance, wind and sand resistance, barren resistance, is the only deciduous tall tree that can be forested in the desert.
Poplar is a great creation of nature.
Just as the special animal of the camel was created in the desert, nature also created the special plant of the poplar. Poplar became the only tall tree in the extremely arid desert that blocked the erosion of wind and sand, and the only unique forest type.
The reason why poplar can adapt to extreme drought and harsh living environment containing saline alkali, and is praised as a desert hero tree, is because poplar has four special features in the shaping of nature for 135 million years: unique historical evolution, unique biological characteristics, unique living environment, and unique original ecological beauty.
Image source: Network
The origin of the name of the poplar is verified
Poplar, Latin literary name Populus euphratica, Willow family, Poplar genus, is a deciduous tall natural tree. The Uyghur language calls poplar "Tokrak," meaning "the most beautiful tree."
After research, the Hu character of the name poplar comes from the generic title of the northwest of China. Hu ben was a self-proclaimed Xiongnu. In the Han Dynasty Xiongnu Mao Dundan yu wrote to the Han Emperor: "There is the Great Han in the south, and there are strong Hu in the north, hu people, and the proud son of heaven." In ancient times, the peoples in the north or the west were called Hu people, and also generally referred to items and plants from northern and western minorities or foreign countries, such as huqin, pepper, carrots, etc. The hu character of poplar indicates that the growth area of poplar is in the northwest, and it is a specific tree species in the northwest. Hu Yang is called Hu Tong in books such as the Book of the Later Han Dynasty and the Biography of the Western Regions, because the poplar tree was mistaken for a tong tree at that time, and later it was determined that the poplar was a Poplar genus, and the name was Hu Yang. Poplar belongs to the poplar school, one of the five schools of poplar trees, and is the oldest species in the poplar genus. Poplars have poplar and gray poplar, and gray poplar requires higher water replenishment and cannot tolerate intensity salinization, but it is generally said that poplar is in both.
Internationally, the Latin name of poplar in plant taxonomy was given by the botanist Di A. Olivier in a travelogue in 1801, Chinese meaning "Euphrates".
Unique historical evolution
When the autumn wind ushers in the frost festival, the 3,800 square kilometers of poplar leaves in the Tarim River Basin shine through and jump under the sunlight, and layers of golden clouds rise in the blue sky. The strong and indomitable branches in the stormy sand shimmer with the splendor of the poplar's gaze, wrestling and straining with the desert for generations.
Poplar's ancestors appeared on Earth as early as 135 million years ago and are truly the world's oldest rare tree species. Poplar has undergone great changes during the ice age and the continental oceans, becoming a surviving left-behind species, exploring opportunities for development.
In the Cenozoic Tertiary Period, 65 million years ago, poplar appeared in the ancient Mediterranean coastal area. The mobile uplift of the continent in the Cenozoic period played a prominent role in the expansion of the habitat of poplar. Poplar gradually evolved with the uplift of the Qinghai-Tibet Plateau into the most important tree species in Xinjiang's riparian forests. At that time, poplar in western China was widely distributed in the Tarim Basin in southern Xinjiang, the western part of the Qaidam Basin, and the Hexi Corridor. In 1935, in the Tertiary Paleocene Strata of Kucha Thousand Buddha Cave in Xinjiang and Dunhuang Blacksmith Ditch in Gansu, the leaf fossils of poplar were found, proving that it was a relict plant of the Tertiary Desert Riverbank, with a history of more than 65 million years. The Tarim Basin was once intertwined with rivers and lined with poplars. In the Qing Dynasty, "hutong (i.e., poplar) was still everywhere in the wilderness and became a deep forest". Today, most of the Tarim Basin, once an oasis,away from the world's second-largest mobile desert, has been reduced to the tarim river, China's largest inland river. The lower Tarim River is reduced, and hundreds of miles of poplar forests are depleted in thirst. Although the Tarim Basin is still home to the world's largest primary poplar forest, the scene of deep forests in those days has become a thing of the past.
In the world, poplar is incoherently scattered in vast areas, and it has its presence in Asia, Europe, and Africa. According to statistics, most of the world's poplar grows in China, distributed in the desert Gobi zone of Xinjiang, western Inner Mongolia, Qinghai, Gansu and Ningxia in the northwest region of China. More than 90% of China's poplars are in Xinjiang, and more than 90% of Xinjiang poplars grow in the Tarim River Basin, the longest inland river in Southern Xinjiang, and on the northern edge of the Taklamakan Desert. Summer temperatures can reach as high as 43.2°C, while surface temperatures can reach over 70°C. When the sun shines directly during the day, the temperature in the desert reaches more than 41 °C, and at night it drops below -39 °C, and poplar can still grow in this alternating high and low temperature environment. The average annual precipitation is 45.2 mm, while the evaporation is as high as 1887-2910 mm. In such a harshest and cruelest environment, poplar evolved into an amazing ability to resist drought, wind and sand, salt and alkali, and cold and heat. The poplar forest is like a green great wall, tightly locking in the expansion of the highly mobile sand dunes.
Unique biological properties
In the long history of more than 100 million years, poplar has been specialized due to desertification, resulting in a series of irreversible changes in the genetic system and phenotype, forming special biological characteristics. The changes in the roots, leaves, branches, cells, reproduction, etc. of poplar make it suitable for the growth of sandy soil, drought tolerance, salinity resistance, cold tolerance, heat resistance, wind and sand resistance, and barrenness resistance, and are the only deciduous tall trees that can be forested in the desert, verifying the eternal truth of "survival of the fittest".
Poplar has a walking root and a perceptual response that is particularly sensitive to moisture. Poplar can smell water, can follow the water, and naturally grows towards the place where there is water. Poplar has a strong root network, and the main root can be deeply rooted below 10 meters. According to scientists, the roots of poplar can still be seen when the groundwater level of 13.5 meters is dug up in the Tarim River. The lateral and horizontal roots of poplar extend outwards, and their roots form a dense network of roots, reaching tens of meters in circumference. The root system of poplar is simply a water machine.
The trunk branches of the poplar can adapt to the abundance of water, and when the water is abundant, the branches are leafy, and the branches are broken and dried. When the water is sufficient, the branches are lush, vigorous, and the water source is poor, the poplar will grow fewer branches and leaves to reduce evaporation, and when the water increases, the growth vitality will be restored, and another derivative will be derived. When the tree begins to age, in order to concentrate water, poplar will gradually break off the branches and trunks of the top of the tree, and finally drop to three or four meters high, still green.
The most peculiar thing is that the leaves of various forms are concentrated on the same tree. In order to reduce the evaporation of water, the leaves on the young branches are narrow and long like curved eyebrows like willow leaves, the leaves on the old branches of large trees are oval and moist like poplar leaves, and the leaves on the old branches are more notched like maple leaves. Therefore, poplar is also known as three-leaf tree, variable leaf poplar, and heterophyllum poplar. In fact, the leaves of poplar are very variable, and even five or six different shapes can grow on a tree.
The reason why poplar can survive in the extremely arid desert without dying is also because it has extraordinary reproductive ability in the struggle and adaptation with nature. Poplar sprouts seedlings directly from its roots. Its seedlings are constantly growing wherever the roots that follow the water go. The horizontal roots of poplar have a strong germination force, and the trees have long roots and roots grow trees, forming a forest of trees. Because of this, the roots of poplar are called "aircraft carriers of life". Poplars bloom purple-red lanceolate flowers in the spring, and in the middle of summer, the trees bear strings of pale yellow oblong capsules. The capsules crack and scatter seeds the size of sesame seeds, which are covered with hairy wings and can be spread in all directions by the wind. Coincidentally, the ripening period of poplar seeds in the northwest is July to September, which coincides with the flooding period of inland rivers, and if the seeds fall on the wet river beach, they can germinate and take root in 4-6 hours, and grow into young trees in two or three days.
The mystery of populus anti-salinity
The reason why poplar can grow in a desert with high salinity and alkali staining is that the physiological structure of poplar can expel excess salinity in the body, and the other is that the trunk, bark, leaves, and roots of poplar itself contain a considerable amount of saline under normal circumstances.
In the desert containing salinity, as long as the roots of poplar cross the saline layer on the surface, the salinity is much less, but it is still impossible to avoid the large amount of salinity contained in the desert. It has long been discovered that poplar automatically excretes excess salt through crumpled skin cracks in the foliage and trunk. The wrinkled skin crack of the trunk is much more excreted from the body, and the alkaloid will drip down the trunk like tears, which is often called poplar tears.
In order to explore the mystery of poplar's ability to grow in saline-bearing fields, in the 1960s, two Australian scientists and an American scientist proposed the "osmosis theory" after years of research: the reason why poplar can survive in saline-alkali land is because the stems and leaves of poplar are covered with salt glands that can excrete too much saline from the body. This is only a preliminary revelation of the salt gland function of populus.
After these three scientists, Chinese scientists have completely unraveled the mystery of Poplar's powerful anti-salinity ability: Poplar's cells have a special structure and function. Poplar's cells have cytoplasm and vacuoles, and there is a diaphragm between the two, and there is a proton pump on the diaphragm. Vacuoles are like warehouses, with too much salinity in the cytoplasm pumping into the vacuoles through proton pumps. After the salinity in the vacuole dissolves with the water, the leaves and branches act in unison, automatically excreting excess salinity through the salt glands of the stems and leaves and the wrinkled skin cracks in the trunk, leaving water for the tree to absorb. This allows poplar to be unharmed by too much salinity and can grow healthily in deserts containing a certain amount of saline.
Unique untouched beauty
Poplars display their original magnificence all year round. The world's only four remaining original poplar forests: Xinjiang Luntai Tarim Poplar Forest, Inner Mongolia Alxa League Ejina Banner Poplar Forest, Xinjiang Shaya "China Tarim Poplar Hometown", Xinjiang Yiwu Poplar Forest Ecological Park Poplar Forest, each place makes people fascinated, lingering. The most amazing thing is the autumn poplar, which is the most beautiful color feast in the world once a year, and the golden picture scroll of wanli is only displayed once a year.
Everyone has a beautiful autumn in their hearts, but the autumn colors are different. Some autumn leaves are colorful, some fruits are rich and fragrant, some autumn scenery is vast and changeable, some are magnificent and magical, some autumn fog is like a dream, and some camel shadows and sheep flocks of golden seas flash. The autumn of the natural original poplar forest blends each scene into one scene, integrating the poplar landscape, natural landscape, river landscape and desert landscape, dotted with a golden yellow, facing the cold autumn wind.
In the desert Gobi, the river is not only the water of life in the Dinggen Desert of Poplar, but also nourishes the magnificent beauty of the poplar. Originating from the Qilian Mountains along the Ejina River, the spectacle of the Ejina Banner poplar forest meanders and stretches, splendid and charming. Along the Tarim River, the 2,179-kilometer-long floodplain is home to poplars, magnificent and stunning. The most noteworthy thing to see in the middle reaches of the Tarim River is the poplar forest in the Tarim River Basin in Luntai County, which is the most concentrated, the most completely preserved, the oldest, the largest and most representative poplar forest in the world.
From west to east, the Tarim River winds through the great desert, and the poplar forests on both sides cover the sky, forming a natural green corridor. Here are the best surviving "Tertiary living fossils" – natural poplar forests that stretch the sky. The golden poplars and the blue sky shine together, and the layers of forests are dyed with gold. After seeing the poplar forest of the wheel, you will certainly not forget the beautiful leaves for a long time, first green, yellow and green in an instant, turning yellow into yellow, and then orange, and soon become a golden yellow that is transparent and transparent in the sun, dreamily entering the colorful fairy tale world.
History and reality are so close at hand. The golden poplar not only paints a long scroll of heaven and earth, but also plays the triumphant song of the endless reincarnation of this ancient and tenacious life on earth. In the Tarim River Old Road, about 70 kilometers southwest of the county seat of Shaya in southern Xinjiang, there is a battlefield where poplar resists raging sandstorms and extreme drought. There are vast tracts of original poplar forests that have been dead for thousands of years, and the locals have named the Devil's Forest. Standing on the high sand hill and looking out into the distance, the north is the endless Oasis of the Weigan River, and in the south is the Taklamakan Desert, which can move the sand dunes with storms, and the Devil's Forest is between the oasis and the desert. The devil forest of about 20,000 acres in the east and west is varied and vigorous, and still preserves the thrilling scene of Hu Yang's life and death struggle. A cluster of poplars is full of vicissitudes, leaving only the body of resistance in the tyrannical sand, or lunging forward, or standing tall in the sky, or creeping branches, although the energy will be exhausted, it is still full of arrogance.
Poplar is the only precious forest resource in desert areas. Poplar forests are a natural barrier to the development of agriculture and animal husbandry in desert areas, protecting the oases on which people depend for their development and the homes on which they depend for their survival. But poplar, which has witnessed hundreds of millions of years of land and sea changes and survived the catastrophe of the Ice Age, is now facing a new disaster of water shortage. The poplar forest in the Tarim Basin, the largest and last poplar forest in the world, is in decline due to water shortages. Fortunately, people have learned from nature's revenge. On June 20, 2016, the special action for the ecological protection of poplar forests in the Tarim River Basin was officially launched: save the Tarim River, save the poplar forests! Be vigilant, don't let the poplar forest disappear in our vision! (High-end Fang Jia Peixin)
About the Author
High-end Fang is a Chinese photographer, a senior reporter of the Economic Daily, and the former vice president of the Capital Women Journalists Association.
Jia Peixin, founder, former secretary general and deputy director of the jury of the Fan Changjiang Journalism Award, the highest award of Chinese journalism, a Chinese photographer, a senior journalist, an editor-in-chief, and a former editor-in-chief of Farmers Daily and China Agricultural Publishing House.
Source: China Green Times
(Edited by Yin Lele)