Plant killer or bridge of life? Why can the banyan tree form a forest?

Have you ever seen a single tree forming a forest? There is a strange phenomenon in the tropical rainforest area that our northern friends cannot experience. It is the Ficus genus of the Moraceae family, which is currently mainly distributed in the southern part of my country.

Why can a banyan tree "become a forest of its own"? This has to do with the tropical rainforest. The rainforest area is in a high temperature and high humidity environment all year round, so the water content in the soil is saturated. However, the oxygen content is relatively low. In order to meet its own breathing needs, the banyan tree will grow aerial roots on its stems and branches. Aerial roots can obtain oxygen and water from the air. When the aerial roots come into contact with the soil, they will become thick and become the prop roots of the banyan tree. The prop roots can support the branches to continue to grow outward, eventually forming the phenomenon of "a forest of its own".

In addition, banyan trees have another unique use. In Cherrapunji, India, a place with the highest rainfall in the world, ordinary wooden bridges are difficult to withstand heavy rain. So local residents use aerial roots, a biological engineering method, to build bridges. They first use the trunk of the betel nut tree to make a simple support bridge, and then pull the aerial roots on both sides of the bridge to the support bridge. When the aerial roots are completely entangled, it will become a natural bridge. This natural bridge will not collapse due to heavy rainfall, but will grow stronger and stronger due to the sufficient rain, so it is also called the "bridge of life."

However, the banyan tree is a nightmare for other woody plants. Since the seeds of the banyan tree are relatively hard, birds usually excrete them in a short period of time after eating them, which makes it very likely that the seeds will be excreted on other plants. Then, the banyan tree will "strangle" the plant.

In the early stage of strangulation, the banyan tree will just "hug" the plant and coexist peacefully. In the middle stage of strangulation, in order to grow better, the banyan tree will pierce the bark of the plant to absorb water and nutrients, and at the same time press on the supporting plant to cause it to be overloaded. The most terrible thing is that in the late stage of strangulation, the strangled plant will rot and die, so the banyan tree is also called the "plant killer."

Another interesting thing is that some banyan trees will drop their seeds on themselves, and some aerial roots will entangle themselves. Do you think it will strangle itself? Please leave a message to tell us your opinion!

Produced by: Science Popularization China, Smart Farmers, Xinglong Tropical Botanical Garden, Chinese Academy of Tropical Agricultural Sciences, National Tropical Plant Germplasm Resource Bank, Guangming.com

Scientific review: Spice and Beverage Research Institute, Chinese Academy of Tropical Agricultural Sciences

Producer: Qin Xiaowei, Zhan Zhao

Co-ordinator: Xie Xiang, Wu Yuetong

Planning: Wei Lai

Guest: Huang Jingping

Filming and Production: Lai Yuhao

Cover design: Tu Ziyi