Why is the rarely seen Yunnan Paulownia endangered?

Recently, researchers discovered a rare and endangered species called Yunnan sycamore in Guoditang Village, Tengchong City, Yunnan Province. Yunnan sycamore mainly grows in Yunnan, and there are only a few hundred of them in the country. Is Yunnan sycamore another name for Yunnan sycamore? Does it belong to the sycamore family? Why is it a rare and endangered species? …

To understand these issues, we must start with the natural environment in southwest my country.

The Yunnan tung tree in Guoditang Village (locally known as the Jiluo tree, source: Tengchong News Network)

Endemic species in the Southwest

Southwest my country has abundant rainfall, dense forests, and 20,000 protected wild plants, accounting for two-thirds of the total in my country. As one of the main provinces in the southwest, Yunnan Province is known as the "kingdom of plants and animals" and is the province with the richest species in my country. There are more than 19,300 plant species in the province, accounting for more than 40% of the total number of plants in my country (46,725 species). ("List of Chinese Biological Species" 2022 Edition)

Tung tree is a species endemic to southwest China, mainly growing in Yunnan, with a small part growing in Guizhou, Guangxi and other places. From 1921 when researchers discovered and named it "Tung tree" in Yunnan to now, it has been found only a few times in the more than 200 years, and the total number is no more than 250 (Science and Technology Daily, May 27, 2020). In February 2020, researchers discovered 31 wild Tung trees in Dahaoping, Tengchong District, Gaoligong Mountain Nature Reserve, Yunnan, which attracted widespread attention from the industry. At present, the Tung tree population in Gaoligong Mountain is the largest Tung tree population in China.

In June 2022, the first blooming of Tung Blossom Trees in Gulinqing Township, Yunnan (Source: China Green Times)

Along with the Yunnan tung, there is also a rare wild plant called the Yunnan tung. The Yunnan tung belongs to the genus tung of the Malvaceae family and is mainly distributed in most parts of Yunnan and Xichang, Sichuan. The IUCN Red List of Threatened Species lists it as an endangered species and a national first-class protected plant. There are only two to three thousand plants in the country.

Although the names of Tung and Yunnan sycamore are very similar, both are perennial deciduous trees and are mainly distributed in Yunnan, but they are completely different in biological characteristics, flower colors, etc. In terms of height, Tung is 20 to 30 meters high when it is an adult, while Yunnan sycamore is generally a few meters to more than ten meters when it is an adult; in terms of flower color, the flowers of Tung are yellow-purple, while the flowers of Yunnan sycamore are purple-red; in terms of lifespan, Tung generally lives for decades to hundreds of years or even thousands of years, while Yunnan sycamore usually only lives for decades; in terms of where it grows, Tung grows mostly in fertile mountains, while Yunnan sycamore grows beside villages or roadsides in addition to living in mountains.

Yunnan sycamore is a "cockroach" that can tolerate drought and barrenness (Photo source: Yunnan News)

Living fossils of the plant kingdom

Tung tree is tall and beautiful, easy to survive in the southwest, and is suitable for landscape trees. It is a national second-level protected key plant and is listed as an "endangered plant" by the China Red List of Species and the World Conservation Union. From the perspective of family, the industry generally believes that it belongs to the genus Tung tree of the Tiliaceae family, and a small number of experts believe that it belongs to the Malvaceae family.

In the 1950s, researchers discovered a plant similar to Tung in Guangxi and classified it as the genus Tung in the Tiliaceae family. However, many years later, they did not find Tung in this only distribution point, and further investigation is needed. In this case, Tung becomes even more important. Because if Tung becomes extinct, it will be extremely detrimental to the study of animals and plants of the same period as it.

The Yunnan tung tree is a very ancient plant. Its growth period can be traced back to the late Tertiary period of the Cenozoic era more than 2 million years ago. It can be called a "living fossil of the plant kingdom."

Due to its age, the Yunnan tung tree has evolved slowly and generally has a long lifespan. In Bakaqing Village, Mojiang County, Yunnan, there is a Yunnan tung tree that is more than 1,000 years old. It is 40 meters tall and its canopy covers an area larger than a basketball court. It is called the "King of Trees" by the locals. What's even more peculiar is that there are several small Yunnan tung trees growing around this tree, clustered together, like a small forest, which is truly a "one tree makes a forest".

The King of Tung trees in Mojiang County, Yunnan (Source: China Green Times)

Tung has very high requirements for the growth environment: the soil must be thick, the water must be sufficient, and the climate must not be too hot or too cold. In addition, the distribution area of ​​​​Tung is relatively narrow, mainly single, two or several plants coexist, there are almost no seedlings around, and the renewal rate is very slow. These two points are one of the main reasons why it has become endangered and rare, and is listed as a very small population of wild plants that are key protected in my country.

Representatives of rare wild plant species

Tung oil tree is a representative of China's extremely rare wild plants. Extremely rare wild plants refer to plants that are affected by various factors in nature, whose populations and individual numbers are lower than the minimum viable population, and may be endangered at any time. The minimum viable population, also known as the stable survival limit, is the minimum effective number required to ensure the stable survival of a population within a specific period of time. Below this amount, the population will gradually decrease until it becomes extinct. Generally speaking, the minimum viable population of woody plants is 5,000 plants. It can be seen that Tung oil tree, with only more than 250 plants in the world, is a standard extremely rare wild plant, which has completely reached the level of "endangered".

Experts have found that there are two natural factors that restrict the growth of very few wild plant populations: one is that the distribution area is relatively narrow; the other is that the distribution is discontinuous, with a long distance between two distribution areas. There are also two human factors: one is that people plant fruit trees and occupy their growth areas; the other is that excessive felling of trees destroys their ecological environment.

In view of the above reasons, the government and the scientific community have targeted the protection of the Yunnan tung tree. On the one hand, the government has set up a certain range of protection areas in its main growth areas to prohibit human destruction of its growth environment; on the other hand, the scientific research team distributed Yunnan tung tree seedlings to local farmers with high enthusiasm and guided them to plant them. Through a series of efforts, the endangered Yunnan tung tree has not only greatly increased in number, but also made great progress in biological protection research.

Experts lead villagers to plant Yunnan tung trees (source of the picture see watermark)

References:

1. "Research on the Conservation Biology of the Endangered Plant Tung Blossom", author Gao Zerui, "Chinese Academy of Sciences Institutional Repository", 2010

2. "Study on the Phylogeny and Biogeography of the Endangered Plants Meconopsis and Meconopsis", author Yuan Changchun, Wanfang Medicine

3. Flora of China, 2004 edition, published by Science Press

Author: Wei Deyong, member of Shenzhen Writers Association, Guangdong