Tokyo: Garden showcases treasure of biodiversity

Photo by Taku Yaginuma / Special to The Yomiuri Shimbun
A reproduced tropical rainforest with tall palm trees

Inside the Green Dome Nettaikan in Itabashi Ward, Tokyo, it feels like lives in summer, even in the depth of winter. Towering palm trees and other flora grow in abundance in the botanical garden, creating a tropical oasis.

About 850 species of plants and fish, mainly from Southeast Asia, are found in the garden, helping visitors feel as if they are in a tropical rainforest.

Tropical rainforests, called “treasure houses of biodiversity,” are said to be home to more than half of all terrestrial life. In Southeast Asia, more than 1,000 species of trees grow on a 50-hectare area in some places. Tropical rainforests are productive and nurture a variety of life, but they are also mysterious places since it is not well understood how so many species can coexist there.

Photo by Taku Yaginuma / Special to The Yomiuri Shimbun
A giant freshwater stingray swims in a tank.

As you follow the visitor’s route through the greenhouse dome from the first basement floor to the second floor, you can see changes in the environment, from the sea to rivers, lowlands and high mountains, three-dimensionally. It is warm inside even in winter as the temperature is kept at 20 C and the humidity at around 70%.

A giant freshwater stingray swims majestically in a tank that re-creates a river. The fish is said to be the largest freshwater stingray species in the world.

A board describing Japanese superb fig as a “strangling plant” caught my attention. The species with the frightening name is often found in Okinawa Prefecture and the Shikoku region.

Photo by Taku Yaginuma / Special to The Yomiuri Shimbun
Vanda, a member of the orchid family

After the plant’s seeds, carried by birds, germinate on a tree, they extend their branches and leaves upward and roots downward, finally surrounding the tree and killing it.

Seeing the plant, I felt like I had a glimpse of the fierce competition for life, for sunlight and nutrients.

Bananas and vanilla can also be observed up close in the botanical garden. Orchid flowers bloom in the cloud forest zone, a re-creation of a mountainous area.

The world’s rain forests continue to shrink due to human development. According to the U.N. Food and Agriculture Organization, 178 million hectares, or five times the land area of Japan, were lost between 1990 and 2010. Ninety percent of these were in tropical regions such as Brazil, the Democratic Republic of Congo and Indonesia. Many plants are said to have gone extinct there before they were even named.

Photo by Taku Yaginuma / Special to The Yomiuri Shimbun
Japanese superb fig, known as a “strangling plant”

Japan imports a lot of timber from Southeast Asia.

“I want people to understand through this experience that the tropical rainforests are connected to our life, and their decline is not someone else’s problem,” said Asumi Takigawa, 39, director of the garden.

Green Dome Nettaikan: 8-29-2 Takashimadaira, Itabashi Ward, Tokyo