Photography: Zhang Zhihe
Cover News Intern Reporter Gou Chun
In recent years, the cute giant panda has won the love of countless people, and watching pandas has become an indispensable itinerary for coming to Sichuan. And why do giant pandas always like to "live" in Sichuan? The reporter searched and found that the six major mountain systems distributed in the current giant pandas, including the Qinling Mountains, the Minshan Mountains, the Qionglai Mountains, the Daxiangling Mountains, the Xiaoxiangling Mountains, and the Liangshan Mountains. Except for the Qinling Mountains that belong to Shaanxi Province, the other five major mountain systems are all in Sichuan, and only the tail of the Minshan Mountains penetrates deep into southern Gansu.
Recently, a reporter from the Cover News learned from the Sichuan Administration of Giant Panda National Park that the "Sichuan Provincial Chronicle·Giant Panda Chronicle" records the formation and changes of the distribution area of giant pandas. The distribution area of
forms the distribution area of
crust movement forms a natural barrier
giant panda population distribution area, concentrated in the Western Qinling fold belt and the intersection with the Kunlun fold belt. According to research, the main mountainous areas in this area were formed during the Paleozoic Carboniferous period to the Mesozoic Cretaceous period. Due to the strongest influence of geological tectonic movements such as the Haixi Movement, Indochina Movement and Yanshan Movement, the time of mountain formation and the influence of geological effects have different results, resulting in significant differences in the characteristics of 's natural geographical .
The Qinling Mountains were formed in the old Tertiary period (70 million years ago). Due to the influence of Yanshan movement, the crust changes occurred, the ground rises, forming mountains. The ground on the north and south sides of the mountain falls, forming the Hanzhong Basin to the south, and forming the Guanzhong Plain to the north; the crust was reactive between the Tertiary Oligocene and the Miocene (26-7 million years ago). Geologically, this crust activity was called one of the Himalayan orogeny, forming wavy mountains, hills and grasslands; The crustal movement between the Tertiary and Quaternary periods (2.5 million years ago) is called the second part of the Himalayan orogeny. This time, the crustal movement is characterized by large-scale faults. Affected by it, the crust undergoes strong differential fault blocks rise and fall. The broad valley and gentle hilly plain formed by the Neo-Terminal orogeny was changed. The Qinling Mountains were faulted in the north and south, the middle and lower reaches of the Yangtze River were broken with the Qinghai-Tibet Plateau , and the eastern edge of the Qinghai-Tibet Plateau formed a complex and diverse topographic landform.
Due to three strong tectonic (orogenic) movements, the Qinghai-Tibet Plateau has risen from the average altitude of about 1,000 meters in the Pliocene to the average altitude of more than 4,000 meters. On the one hand, the uplift of the plateau has led to a huge change in the Asian monsoon circulation, which has left eastern China and southern China under a relatively warm and humid monsoon climate environment since the Meso Pleistocene; on the other hand, it has aggravated the arid and desertification in the northwest inland, and promoted the formation of China's three major climate regions (the Qinghai-Tibet Plateau and the adjacent high-altitude zone, the western arid zone and the eastern monsoon prevalence zone). In addition, the uplift of the Qinghai-Tibet Plateau may have affected the transformation of global climate fluctuations, promoting the formation of alternate cycles of cold and warm periods with a period of approximately 100,000 years since the Middle Pleistocene.
From the perspective of the phylogenetic evolution history of giant pandas, the end of the Miocene is the initiation period of giant pandas; the giant panda small species in the early Pleistocene are in the growth stage of giant panda phylogenetic, and their distribution range is further expanded; in the middle and late Pleistocene, the giant panda Pasteur subspecies flourished unprecedentedly, but are mainly distributed in areas where the monsoon can penetrate deep in southeastern China. In short, in the process of the evolution of the giant panda system, the continuous uplift of the Qinghai-Tibet Plateau and the high-altitude environment caused by it have become a natural barrier for the expansion of the giant panda distribution range. On the other hand, the existence of the Qinghai-Tibet Plateau during the Pleistocene Glacier Age weakened the advancement of cold air flowing northwest to the southeast region to a certain extent. The various complex terrain and landforms formed by the plateau uplift in central and western China provided various possible refuges for the continued survival of giant pandas during the Pleistocene Glacier Age. Therefore, it became the last habitat of living giant pandas in the eastern edge of the Qinghai-Tibet Plateau and the middle section of the southern slope of the Qinling Mountains.
live giant panda distribution area, located in the second step of the three major terrain in China. This "step-type" terrain that reflects the differential tectonic movement of the earth's crust is mainly affected by the two-level tectonic lines in the east and north and east directions. The arrangement of mountains is almost consistent with the direction of geological structure.The spatial distribution pattern composed of these mountains is tilted from northwest to southeast. The Qinling Mountains lie across the northern edge of the region, becoming the dividing line between the north and south China's climate. It not only blocks the invasion of the cold current from the north, but also helps the depth of the southeast and southwest monsoons, leading to the complex and regular transitional alternation of the natural landscape, and also makes the climate of the north and south slopes of the Qinling Mountains very different. The southern slope belongs to the northern subtropical zone, and the northern slope belongs to the warm temperate zone, and is the intersection of flora components in central, north and west China.
Photography: Li Yunxi
Distribution area changes
Complex terrain creates a superior environment
Historically, giant pandas have a wide distribution area, generally located between 95° to 120° East longitude and 23° to 41° North latitude, and belongs to the Northern Subtropical. The climate in this area is warm and humid, densely packed with forests and numerous bamboo species. It is not only suitable for the survival of giant pandas, but also forms a giant panda - saber-toothed tiger and saber-toothed elephant animals.
However, with the changes in geological structure and climate, the evolution of animal and flora and population growth, especially the sharp decline in forest resources, has seriously threatened the living environment of giant pandas, and a large number of ancient animals and habitats have suffered devastating disasters. At the same time, from the late Pleistocene to the early Holocene (15,000 to 10,000 years ago), humans entered the Neolithic Age (Hocene), strengthening their survivability and living ability, constantly expanding their scope of activities, and destructively changing the forest ecological environment through cutting, burning wasteland, reclamation, hunting, war, etc., and reducing the food bases of giant pandas, and disappearing habitats, and greatly reducing the distribution range to a historical period with written records. Only some distribution areas have been preserved in Sichuan, Shaanxi, Gansu, Henan, Hubei, Hunan, Guizhou and Yunnan.
About 2500-3000 years ago, giant panda populations were also distributed in the northwest region and the Yellow River Basin. Later, due to the destruction of war and the losses caused by natural disasters and deforestation, severe desertification and desertification in the northwest region were caused. Not only did it greatly restrict the development of economy and culture, but also giant pandas and other specialty animals also lost hidden conditions and food conditions, and had to seek suitable places to survive.
In the past century, the distribution area of giant pandas has continued to retreat westward, and is only distributed in the river source of each tributary such as the Hanshui , Jialing River , Fu River , Tuojiang , Minjiang , Qingyi River , Dadu River and Anning River in the Yangtze River Basin, namely the eastern edge of the Qinghai-Tibet Plateau, the mountains in northwest Sichuan, the mountains in southern Gansu and the Qinling Mountains, and is located between 101°51′00″～108°47′57″ and 28°12′00″～34°00′18″. The distribution area starts from in Ningshan County, Shaanxi Province in the east, ends at in Jiulong County, Sichuan Province in the west, to in Zhouzhi County, Shaanxi Province in the north, and to in Leibo County, Sichuan Province in the south, with a total area of about 23,000 square kilometers. From a geographical perspective, the distribution latitude of ancient giant pandas spans about 18° and the longitude spans 25°; while the distribution area of the existing giant pandas spans only nearly 6° and the longitude spans only nearly 7°, and its distribution range has been greatly reduced.
The six major mountain systems distributed in the Qinling Mountains, Minshan Mountains, Qionglai Mountains, Daxiangling Mountains, Xiaoxiangling Mountains, and Liangshan Mountains. Except for the Qinling Mountains that belong to Shaanxi Province, the other five major mountain systems are all in Sichuan, and only the tail of the Minshan Mountains goes deep into southern Gansu.
Due to the different distribution ranges of mountain systems and the complex topography of each mountain system, the huge altitude difference, and the diverse climate types, it constitutes a special natural environment and complex and diverse ecological types, which are suitable for the survival and reproduction of a variety of organisms. It is rich in biodiversity, creating a superior environment for giant pandas and other rare, ancient and special animals. At the same time, the forest areas in which giant pandas live are warm and semi-temperature warm temperate mountain forests and subtropical mountain forests. The obvious characteristics are abundant rainfall, humid climate, and abundant water resources. They are distributed with coniferous forests, broad-leaved forests, and coniferous and broad-leaved mixed forests. There are more than 40 kinds of edible bamboos in giant pandas, which have various conditions required for giant panda activity habits and selection of staple bamboos.According to the survey, the relative richness of giant pandas in coniferous forests in the above distribution area reached 54≰44%, and the relative richness of broadleaf forests reached 40≰04%, and the total of the two was nearly 95%. Therefore, giant pandas chose these places to survive. The land resources, water resources, climate resources, forest resources and various other natural resources in its distribution area are all indispensable and important factors in the living environment of giant pandas.
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