Can a single tree form a forest? Did the Hanging Gardens of Babylon really exist? A list of the top ten wonders of the tropical rainforest

Top 10 Wonders of the Rainforest

Chen Zhiheng, College of Tropical Agriculture and Forestry, Hainan University

Flowers on old stems

There are many cases of flowers blooming on tree trunks and old branches in the tropical rainforest. The formation of flowers on old stems is related to the special environment of the tropical rainforest. It is a biological phenomenon formed by plants gradually adapting to the environment during evolution. Trees in the middle and lower layers are at a disadvantage when competing with upper layer plants for sunlight, and flowers cannot occupy high branches to attract pollinators. Therefore, they choose to bloom flowers in relatively open positions on old branches and trunks, making the flowers easier to be discovered and visited by insects, which is conducive to reproduction. In addition, the stem flower phenomenon facilitates the transportation of nutrients and reduces energy consumption, and the thick trunks can also withstand the weight of the fruit.

Sky Garden

"Sky Gardens" are also called "crown gardens". They refer to the phenomenon that many kinds of epiphytes and climbing plants live and grow on the above-ground parts of rainforest trees. In the rainforest, because the trees are usually very tall and the crowns are dense, relatively little sunlight reaches the ground. And near the ground, there are a large number of shrubs and small trees growing densely, and most low-growing herbaceous plants will find it difficult to get enough sunlight. However, there are many opportunities on the trunks and crowns of trees. Therefore, some "smart" low-growing or climbing plants discovered such a great opportunity and slowly evolved the "unique skill" of leaving the ground and living in trees to compete for more sunlight.

Dripping leaf tip

Also known as dripping tip, it mainly refers to the phenomenon that water on the leaves of most plants in the tropical rain forest flows down along the leaf tip. The formation of dripping leaf tips is related to the hot and rainy environment of the tropical rain forest. The relative humidity is extremely high, and the water vapor in the air and the rainfall that occurs at any time often form a layer of water film on the surface of the leaves. In order to remove these water films, after millions of years of evolution, these leaves have formed tail-shaped leaf tips. The drooping tail-shaped leaf tips can easily guide the water film on the surface of the leaves to gather together and become water droplets to flow down, thus forming the unique landscape of "dripping leaf tips" in the tropical rain forest.

Giant leaf phenomenon

The giant leaf phenomenon refers to the fact that many species of plants growing in tropical rainforests have huge leaves. The huge leaves can receive more sunlight and grow well. The large leaves can accommodate several people under the leaves to shelter from the rain. It is generally believed that this is the result of tropical rainforest plants and plants adapting to weak light.

Colorful Rainforest

It means that many tree species in the rainforest will grow new leaves in all seasons. The new leaves of various plants are particularly eye-catching in the vast "green sea" of the rainforest, making the rainforest colorful and full of charm from a bird's-eye view. This is an ecological countermeasure made by plants to adapt to the rainforest's year-round warm and suitable environment for growth. The red, yellow and other colors of young leaves can protect the leaves and reduce the damage of ultraviolet rays and the nibbling of herbivores.

Strangulation

It refers to the situation that after the fruits of strangler plants are eaten by birds, the seeds are not digested and are excreted on other trees. Under suitable conditions, these seeds germinate and grow many aerial roots. The aerial roots grow along the host tree trunk to the ground and insert into the soil, robbing the host plant of nutrients and water. These aerial roots gradually thicken and branch, forming a root network that tightly clamps the main trunk of the host tree, preventing the growth of the host plant. As time goes by, the aerial roots of strangler plants grow more and more, and grow more and more luxuriant, while the strangled host plant eventually dies and rots due to the oppression of external strangulation and lack of internal nutrients. The main trunk of the strangler plant is only a circle surrounded by aerial roots, which looks like a pig cage. In the tropical rain forest, there are 20 to 30 species of banyan trees with strangling functions. They often choose some tall and upright hosts as strangling targets, so that they can more easily obtain a wider ecological niche, and the host will also provide more nutrients after being strangled to death. The phenomenon of strangulation is a very cruel fact of competition among plants, which is quite similar to the "crow occupying the magpie's nest" in the animal world.

Buttress root phenomenon

Also known as plank roots, they refer to the huge flanks at the base of some tall trees in the rainforest, which can be several meters high and several meters wide, and have the functions of supporting, absorbing nutrients and breathing. Plank roots are a special adaptation of tall trees, which can well avoid the problem of "top-heavy" caused by the wide crown and heavy upper body. They effectively strengthen and support the above-ground part, can also resist the attack of strong winds and rainstorms, and have the function of retaining moisture. It solves the dilemma of tree roots in tropical rainforests that it is difficult for them to enter the deep soil while supporting the above-ground part.

Climbing vines

It refers to the vine-entangled scene formed by a wide variety of vines. Hainan vine taro that grows on trees, dense centipede vines and vines with twisted roots that stretch across the rainforest, together form a series of rainforest wonders. They compete to climb and receive the baptism of sunlight. Cliffs, rocks or lush trees are all the support of these climbing plants. In the tropical rainforest, it is common to see lush trees surrounded by climbing plants. This is also an ecological countermeasure formed by vines to compete for more sunlight and living space.

A single tree makes a forest

As banyan trees grow, they produce "aerial roots" on their outstretched branches. The newly grown "aerial roots" are like long, thin beards, hanging down. When they fall into the soil, they gradually thicken and slowly become prop roots. The prop roots can absorb water and nutrients, while also supporting the branches that continue to expand outward, so that the original crown continues to expand. These constantly formed prop roots are like many feet, constantly expanding the territory, day after day, forming a spectacular scene of covering the sky and blocking the sun, and a single tree forming a forest. This is a unique landscape formed by competing for more sunlight and living space. At the same time, it also strongly supports the huge crown, helping these trees to gain a foothold.

Root boulder

Also known as "trees on rocks", this phenomenon usually occurs in banyan trees in tropical rainforests. The huge tree roots grow around the rocks, and eventually the aerial roots will continue to grow along the rocks, forming trees on rocks. This is a unique phenomenon formed by rainforest plants in order to compete for more growth space. This can help plants obtain more stable growth conditions, and also reflects that the rainforest has very rich water and heat conditions.