Overview of meridian in Ziwuling

Ziwuling, also known as Hengling and Qiao Shan, spans Shaanxi and Gansu provinces and is located in the hinterland of the Loess Plateau. Because it is in the same direction as the prime meridian, it is called Ziwuling. Ziwuling forest area is a well-preserved natural vegetation area in the Loess Plateau and an important ecological public welfare forest in the central part of the Loess Plateau.

Ziwuling is located in the uplift mountain between the famous Dongzhiyuan and Luochuanyuan, facing Bai Yushan and Laoshan in the northeast, and connecting with Weibei Plateau in the south. Its northern section extends from Huachi, Gansu, from northwest to southeast to the south of Guoyuling, Huangling, and is divided into two branches, which extend into the source of Luohe and Luo Jing respectively, forming a watershed of Luo Jing water system. The west branch at the southern end extends to Xunyi County, Shaanxi Province, with Shimen Mountain as the highest point and an altitude of 1885 meters. The east branch extends to Yijun, Tongchuan and Yaoxian County, forming Yijun Beam. The main peak of Ziwuling is1.687m above sea level, located at the left source of Qushui River. Others, such as the pier beam at the junction of Ganquan, Zhidan and Fuxian (elevation1.625m), Wulidun in the upper reaches of Qushui River (elevation1.625m) and Qiquanmiao Mountain in Yijun (elevation1.734m), are all meridian.

Ziwuling is located at107 30 ′ ~109 40 ′ north latitude and 33 50 ′ ~ 36 50 ′ east longitude. Including Huachi, Heshui, Zhengning and Ningxian in Gansu, and Fuxian, Huangling, Yijun, Tongchuan, yintai district, Yaoxian and Xunyi in Shaanxi, with a total area of 23,000 square kilometers, including 4 counties in Gansu and 6 counties in Shaanxi. The terrain is high in the south and low in the north, and it inclines from west to northeast, with an altitude of11700m and a relative height difference of 300 m. The top of the headland is round and gentle, with an inclination of 3 ~ 5, and the gully slope is steep up and down, which is10 ~. This area is located in the transitional zone between forest grassland and semi-arid grassland, with mild and humid climate. The northern half of the region has a temperate semi-arid climate in north-central Gansu, and the southern half has a temperate semi-humid climate in south-central Gansu. The annual average temperature is 7. 14 ~ 8. 15℃, the extreme minimum temperature is -27. 17℃, and the extreme maximum temperature is 36. 17. There are rivers 15 in the area, including Malian River in Jinghe River Basin and Hulu River in Beiluo River Basin.

Xuanyuan Huangdi, the ancestor of China, was the first to move in this area, "migrating and pulling out mountain roads", cutting through thorns and opening up wilderness. His mausoleum is located on the Qiaoshan Mountain in the east wing of Ziwuling, so Ziwuling is also called "Sage".

1980, the millionth o n c (operational n navigation chart) film compiled by the Institute of Geography, China Academy of Sciences shows that Qin Zhi Road does exist on the Ziwuling at the junction of Shaanxi and Gansu. The history of Qin Daoism is called "Daoism in the Cloud", commonly known as "Emperor Daoism" and "Sage Articles". After Qin Shihuang unified China, the Great Wall along the Yangtze River was built to resist the invasion of Xiongnu. After more than 2,000 years of wind and rain erosion, Qin Zhi Road is still clearly identifiable, and some sections are still open to traffic.

Ziwuling not only has beautiful plateau and forest scenery, but also has a long and splendid historical and cultural heritage and rich animal and plant resources. There are more than 200 kinds of wood and economic trees such as pine, cypress and birch growing in Ziwuling. There are more than 50 species of wild animals such as leopard, deer, civet cat and black stork/kloc-0.

Ziwuling forest is not only an economic forest, but also an important ecological forest, which is known as the "green barrier" in Longdong and the "natural reservoir" in the Loess Plateau.