The significance of Qinling-Huaihe line is the geographical dividing line between north and south. There are obvious differences between the north and the south of this line in natural conditions, agricultural production methods, geographical characteristics and people's living customs. Qinling-Huaihe line is the 800 mm isorainfall line in July, the traditional north-south dividing line, the distribution dividing line between paddy field and dry land, the 1 0℃ isotherm, the rice-wheat planting dividing line, the dividing line between subtropical zone and warm temperate zone, the dividing line between humid and semi-humid zone, and the dividing line between subtropical monsoon climate and temperate monsoon climate. As well as the north-south boundary line in China and the rivers in most areas north of Qinhuai are frozen or not, and rivers and lakes are frozen in winter. When winter comes and the north wind whistling, most trees will lose their leaves, and those that don't lose their leaves are mostly needles, which are called conifers. Because the annual precipitation in the northern region is less, and the precipitation is mostly concentrated in summer, the river water volume is small and the water level changes greatly. The flood season is only formed in summer, the time is relatively short, and the river sediment concentration is relatively large. In the south of Qinhuai, on the other hand, there is no ice in winter, no deciduous trees and evergreen seasons. The river has large water volume, small water level change, long flood season and small river sediment concentration. From the perspective of agricultural production and people's living customs, the difference between the north and the south of Qinhuai is more obvious. The cultivated land in the north is dry land, and the main crops are wheat and miscellaneous grains, which are harvested twice a year or thrice every two years; Paddy fields are the main crops in the south, and subtropical cash crops such as rice, sugarcane and tea are the main crops. Two or three seasons a year. People usually say that "northern wheat and southern rice, southern boats and northern horses" is a true portrayal of this difference. The Huaihe River Line in Qinling Mountains passes through Gansu, Shaanxi, Henan, Anhui and Jiangsu provinces, which is an important geographical dividing line in eastern China. There are significant differences in climate, rivers, vegetation, soil and agricultural production between the north and the south. Geographical significance of Qinling Mountains

There is an east-west mountain range in central China-Qinling Mountains. It is like a "wind wall", which blocks cold air from going south in winter and southeast monsoon from going north in summer. Since ancient times, due to the special geographical environment in which the Qinling Mountains are located and the differences in climate change, cultural landscape and living customs between the north and the south of the Qinling Mountains, it has been called the dividing line between the north and the south of China. Traditionally, the south of Qinling Mountains is the south of China, and the north of Qinling Mountains is the north of China. However, the official name of Qinling Mountain began to exist only in the Han Dynasty. The Qinling Mountains in a broad sense is a huge east-west mountain range across the central part of China, starting from Baishi Mountain in the north of Lintan County in Gansu Province in the west and bounded by Dieshan Mountain and Kunlun Mountain. Enter Shaanxi eastward through McKee in the south of Tianshui. At the junction of Shaanxi and Henan, it is divided into three branches, the northern branch is Xiaoshan, and the remaining veins extend eastward along the south bank of the Yellow River, commonly known as Mangshan; The middle branch is Xiong 'er Mountain; The south branch is Funiu Mountain. A small part of the southern part of the mountain range extends from Shaanxi to Yunxian County, Hubei Province. The Qinling Mountains are 1600 kilometers long and tens of kilometers to two or three hundred kilometers wide from north to south. They cover a vast area and are magnificent. In a narrow sense, Qinling refers to the middle part of Qinling, which is located in the middle of Shaanxi Province. It was called "Qinling Mountain" in the Han Dynasty, and it was named "Nanshan" because it was located in the south of Guanzhong. Geographical significance of Huaihe River

The Huaihe River to the east of Qinling Mountains is a big river in China, with a total length of 1000 km. The topography, rivers and hydrological characteristics on both sides of the Huaihe River are different. [Edit this paragraph] The concept of Qinhuai River Line, as an important geographical concept in China geography, was put forward by the famous geographer Zhang. The record in Newly Edited Geography (1908) is on page 185 of Newly Edited Geography published by Zhang Yu 1908: "The northern belt starts from Huaishui in the north and reaches the Yinshan Great Wall in the north. Animals train donkeys, horses and goats; There are many musk rhinos in the west. There are many plants, including bitter orange, elm, sandalwood, pear, chestnut, persimmon and grape. " This is Mr. Zhang's description of northern China. The so-called "southern boundary" is the north-south boundary [3]. This is the earliest known exposition on the Qinling-Huaihe Line. In Zhang's anthology "Nan Yuan Cong Draft", the article "Buddhist Geography" published by Zhang 1924 was included, and it was clearly mentioned that Qinling-Huaihe River divided China into north and south. The article describes China as follows: He first divided China into six parts. He wrote these six films like this: "Japan, Mongolia, Manchuria, Xinjiang, Tibet, Qinghai. The land of the headquarters, or Yu Yu, is also called Hantu. ..... In terms of natural conditions, it is divided into three zones: north and south. The northern region is the Yellow River Basin. The south is bordered by Beiling and Huaishui ... "Speaking of the Huaihe River, he said:" The Huaihe River originated from the Beiling branch. It is the dividing line between north and south. " It has been made clear here that the Huaihe River is the dividing line between north and south. It shows that as early as 1924, Mr. Zhang divided China into north and south with Qinling and Huaihe rivers. According to the following description, it is known that Zhang's Beiling is today's Qinling Mountains (it seems that people didn't call that mountain Qinling at that time). Why is it called Beiling? Maybe it's because the south is opposite to Nanling. In the first year of the Republic of China (19 12), the book Geography of China, in which the Qinling-Huaihe line has appeared. As the book says, "In the country. Due to the potential of mountains and rivers, administrative districts can be defined as headquarters, northeast, northwest, north, west and five major departments. " For the headquarters. The book says: "The north-south ridge is divided into three zones horizontally. The Yellow River, the Yangtze River and the Pearl River flow through here. North of the Huaihe River in Beiling is the northern belt, which is the Yellow River Basin ... "This textbook has a description that this book is mainly written according to Zhang's geography textbook. In a paper entitled "An Introduction to Climate in China" written by Zhu Kezhen 1935, Mr. Zhu explicitly talked about the Qinhuai River Line. But he is talking about a foreigner, keresey, who wrote a book "The Geographical Basis of China" at 1934. The book writes: "Among the mountains in China, the largest is the eastern branch of Kunlun Mountain, and the common name of China is Qinling Mountain, which runs from Tibet to the east to the Pacific coast. This mountain range is divided into two geographical regions in China, and there are significant differences in climate, agriculture and human activities. " Of course, it seems that the statement that the Qinling Huaihe River Line was put forward by foreigners is obviously wrong. Mr. Zhu Kezhen went on to say, "Anyone who has been to the Qinling Mountains has never failed to pay attention to the differences between the northern and southern parts of this mountain range. The reason is that the climate is obviously different, which makes the plant species, travel modes and human characteristics in North China and South China very different. " In an article published by Weng 1936, Soil and Related Life Problems in China, it has been clearly stated that Qinling-Huaihe River is the natural dividing line of China. But he said it from the perspective of soil. Mr Weng said that the soil in China can be divided into two categories. Qinling Mountains and Huaihe River are mostly calcareous soil in the north, and almost all of them are residual soil in the south ... In ancient times, Qinling Mountain was called the time limit of China, and so was the soil distribution. [Edit this paragraph] The natural range of dividing line is divided into Qinling-Huaihe line. From the name, its drawing seems very simple. Draw a line along the Huaihe River in Qinling Mountains. However, when you face a large-scale map of China, you will find that there is no way to start: the Qinling Mountains start from Baishishan in Gansu in the west, and McKee in the south of Tianshui in the east enters Shaanxi. At the junction of Shaanxi and Henan, it is divided into three branches, the northern branch is Xiaoshan, and the remaining veins extend eastward along the south bank of the Yellow River, commonly known as Mangshan; The middle branch is Xiong 'er Mountain; The south branch is Funiu Mountain. The Qinling Mountains and Huaihe River are divided into north and south, only the east of China. How to divide the western part of China into north and south parts is very interesting. The west can be divided into two regions, but the north and south are reversed, and the cold and hot are reversed. To the west along the Qinling Mountains, there are roughly two east-west mountains connected with the Qinling Mountains: one is Qilian Mountain, which is connected with Altun Mountain all the way west; The other is the Kunlun Mountains, which starts from Pamirs in the west and stretches for more than 2,000 kilometers to the east. If the Qinling Mountains are divided into north and south to the west, these two mountain systems can be considered [1]. The distinction between north and south mentioned here is not a cultural concept, but refers to the distinction between north and south in natural geography, specifically the distinction between subtropical zone (south) and warm temperate zone (north). The subtropical and warm temperate zones of physical geography are defined and standardized. Liu Jiaoshou from the Department of Geography of Shaanxi Normal University has been studying the Qinling Mountains for many years. He advocated drawing the north-south boundary line at the 800-meter contour line on the southern slope of Qinling Mountain. According to Mr. Liu, the subtropical zone has ended at the contour line of 800 meters above sea level, because the altitude of the mountain is gradually rising and the temperature is dropping, and the indicator plants of the subtropical zone such as oranges and bamboos are no longer visible. The south should stop here, so the north-south boundary of China should coincide with the 800-meter contour of the south slope. Examples of Three Maps of China's North-South Boundary The late famous geographer Ren Meihua advocated drawing China's North-South Boundary at the 700-meter contour line on the northern slope of Qinling Mountains. Because from the northern slope of Qinling Mountains, the whole Guanzhong Basin is a warm temperate zone, but with the rise of mountains, the temperature drops. At the 700-meter contour, the climate is not warm temperate, but mountainous. The higher it is, the colder it is. In fact, Mr. Ren Meihua regards Qinling Mountain as a mountain system in warm temperate zone. Other geographers, such as Huang, advocate that the north-south boundary should be drawn on the main ridge line of Qinling Mountains. The reason is that it can keep the integrity of the vertical natural belt on both sides of the mountain, just to compare the two and see the difference between the north and the south. But there is no clear ridge line in Qinling Mountains. How to divide this method is still unknown. You can also connect the highest points of some high-altitude peaks and count them as the ridge line of Qinling Mountains. In the book China Eco-geographical Regional System Research published in 2008, Academician Zheng Du and others made a detailed comparative analysis of the climate and vegetation in the north and south of Qinling Mountains, and classified the natural environment of Qinling Mountains by using the latest scientific and technological means. Finally, from a comprehensive point of view, the dividing line between China warm temperate zone and subtropical zone in Qinling area should be drawn at the main ridge. In fact, the natural dividing line between north and south in China is the climate dividing line first. As far as the hot zone is concerned, it is the dividing line between the northern warm temperate zone and the southern subtropical zone; In the division of water, it is the dividing line between the arid and semi-humid climate in the north and the humid climate in the south; In the division of rainy season and dry season, it is the dividing line between spring drought and summer rain climate in the north and spring rain, plum rain and summer drought climate in the south [2]. However, this transition and change is completed through a fairly wide belt. We can't see any changes in climate, agriculture, natural landscape, etc. on both sides of the Huaihe River, which are more than ten or twenty kilometers apart. In fact, because the Huaihe River area is mainly a plain area, the cold and warm air flow between the north and the south is unimpeded, and it is really impossible to produce a clear north-south dividing line. Take "orange crossing Huaihe River, turning north into bitter orange" as an example. Due to the strong cold air in the central and southern parts of eastern China in winter, it often brings fatal low temperature to citrus. Therefore, even on the banks of the Yangtze River south of Huaihe River, except for some favorable areas, citrus cultivation generally has no economic value. The Qinling Mountains to the west of the north-south boundary block the cold air in the north in winter, so Lingnan is a typical subtropical zone (it can grow citrus and other subtropical index plants that can't grow on both sides of Huaihe River at the same latitude) when it is a typical warm temperate zone to the north of the ridge. However, the Qinling boundary is not a line. Because the southern slope of Qinling Mountain is subtropical only at an altitude of 1000 meters, and the width between the contour lines of the two slopes of Qinling Mountain, that is, the width of the boundary zone, is about 90- 1 10 km. Moreover, in history, the north-south boundary zone moved north and south with climate change. If global warming continues, the subtropical northern boundary may even move northward to the middle and lower reaches of the Yellow River in the future. [Edit this paragraph] Important geographical boundaries

The geographical significance of 1. Temperature 1, 1 October temperature1. 2. Isograms of daily average temperature ≥ 10℃ and accumulated temperature ≥ 4,500℃. 3. The dividing line between warm temperate zone and subtropical zone. 2. precipitate 4. Isoprecipitation line with annual precipitation of 800 mm. The dividing line between wet zone and semi-wet zone. 3. Climate 6. Subtropical monsoon climate. Agriculture. The boundary between dryland agriculture and rice agriculture. The boundary between rice production and wheat production. Vegetation 9. Boundary between evergreen broad-leaved forest and deciduous broad-leaved forest. River 10. The river flow to the north of this line is large, and the water level changes little. The river flow to the south of this line is small during the ice age, and the water level changes greatly. There is no ice age 1 1, Qinling Mountains (and Bayan Kara) or the Yangtze River and the Yangtze River. The terrain south of the line is broken, mainly basins and hills. Eight. Region 13, South China-North China boundary line 14, Central China-North China boundary line.

1. Geography: the dividing line between the north and the south of China. 2. Climate type: the dividing line between temperate monsoon climate (north) and subtropical monsoon climate (south). 3. Temperature zone: the dividing line between warm temperate zone (north) and subtropical zone (south). 4. Natural belt: the dividing line between temperate deciduous broad-leaved forest belt (north) and subtropical evergreen broad-leaved forest belt (south). 5. Typical vegetation: the boundary between temperate deciduous broad-leaved forest (north) and subtropical evergreen broad-leaved forest (south). 6. On the soil: the dividing line between brown soil (north) and red and yellow soil (south). 7. Hydrology: the watershed between the Yellow River system and the Yangtze River system. 8. Dry and wet area: the dividing line between semi-wet area (north) and wet area (south). 9. Topographically: the dividing line between the North China Plain and the middle and lower reaches of the Yangtze River. 10, 1 monthly average temperature 0℃ isotherm passes through this area. 1 1, and the annual precipitation is 800 mm 12. Agriculture: the dividing line between the main wheat producing areas (dry farming in the north) and the main rice producing areas (paddy farming in the south). 13, the northern limit of the growth of subtropical fruit citrus (citrus is born in the south). 14, the watershed between the Yangtze River and the Yellow River