Introduction

The living organisms that bring about various changes in the environment through their activities are called biotic factors. Biotic factors in the tropical rainforest are the living elements in this zone. These are plants, animals, insects, fungi, and microorganisms. All these biotic factors in the tropical rainforest are discussed in detail below.

Biotic factors in the tropical rainforest are the primary cause of the high level of biodiversity in this area. So biotic factors play a significant role. The abundance of plants and animals in the rainforest is, in fact, richer than any other habitat. Although their amount has sometimes increased and decreased during the last few million years of climatic changes, it is still one of the oldest ecosystems on Earth.

Tropical rainforests are home to millions of species, making up 50-80% of all living organisms. In each hectare of the rainforest, there can be up to 42,000 plant species, 2500 bird species, 500 mammal species, and 3000 fish species. Additionally, there are likely millions of undiscovered species living in the rainforest. These biotic factors, along with abiotic factors, create the complex and diverse ecosystem of the tropical rainforest (1).

What is a tropical rainforest?

Areas located between 10 degrees north of the equator and 10 degrees south of the equator where the temperature is constantly high and where annual rainfall exceeds 800 to 2500 mm and the forests that grow in warm and humid regions are called tropical rainforests.

Some interesting facts about tropical rainforests are

• Tropical rainforests always have warm and humid weather. There is no dry season here.
• It is also known as the lowland equatorial evergreen rainforest.
• The tropical rainforest is a type of tropical moist broadleaf forest.
• Rainforests are generally found between 10°N and south of the equator.
• The average monthly temperature here exceeds 18°C in all months of the year.
• Here the average annual precipitation is not less than 1680 mm.
• It is one of the highest biodiversity zones in the world.
• Because of heavy rains in those regions, the soil is always wet, and thus the forests are evergreen.
• The evergreen rainforest retains its green color all year because the trees shed their leaves one by one instead of all at once.
• The forests of this region are so dense that sunlight cannot reach the ground. Therefore, it is dark even during the daytime. Therefore, this forest area is called the “land of eternal twilight”.
• Soil is very soft due to humidity in the forest (3) & (4).

What is an abiotic factor?

Abiotic factors refer to non-living components of an environment that can impact the organisms living there and the ecosystem’s functioning, as opposed to factors that come from living organisms or biological activity.

Water, soils, various minerals, and gaseous substances are the abiotic factors of ecosystems. Green plants use all these elements in food preparation. They are the nonliving things of the environment.

The abiotic factors of the tropical rainforest are temperature, soil type, humidity, and sunlight (4).

List and details of all the biotic factors of the tropical rainforest

Biotic factors are the living organisms of the environment. Tropical rainforest biotic factors are

Plant species

There are about 42,000 types of plant species found in tropical rainforest areas. One hectare of tropical rainforest is home to 500 species of small trees and 2000 species of higher plants. There are also various types of angiosperm plant species found in this region. These include orchids, heliconia, lilies, bromeliads, etc.

Various flowers, herbs, woody vines, lichens, and mosses can be noticeable in this rainforest zone. Some plants such as rosewood, ironwood, mahogany, banana trees, rubber trees, bamboo trees, cassava, avocado, kapok trees, epiphyte, lobster-claws, cacao, palms, bougainvillea, pitcher plants, etc. are found in this region (1).

Characteristics of plants

• Plants grow relatively faster because of the humid environment.
• The forest is so dense that the sunlight cannot reach the ground.
• Trees are very tall. The trees are about 40-50 meters long or more.
• The leaves of the tree are quite broad and long and remain green throughout the year.
• Hence the forests of this region are known as evergreen forests.
• Trees spread their branches and cling to each other and form a canopy like an open umbrella.
• Different species of trees are seen per hectare.

Layers of plant species

1. First layer

This layer consists of the tallest trees. As the leaves of these trees are large, they form a cover like an umbrella or canopy. This layer receives maximum sunlight and rainfall. The height of this layer’s trees is 40 to 60 meters. That is why it is called the dominant layer.

2. Second layer

The plants in this layer are located slightly below the plants in the first layers. Their height is about 20 to 40 meters.

3. Third layer

Plants present in these layers are 15 to 20 meters tall. The leaves of trees at this level are broad to absorb most of the sunlight that penetrates the upper layers.

4. Fourth layer

There are no big trees found in this layer. The height of the plant of this layer is about 5 to 10 meters. They are isolated in the forest. Plants in this layer do not stay at one height for long. After a few days, they moved upwards.

5. Fifth layer

Plants in this layer are ferns. Their height is only 1 to 2 meters from the surface. The species diversity of these plants is quite low. As the amount of sunlight received decreases, the density of this layer decreases (2).

Animal species

There are various types of animal species found in tropical rainforests. About 3500 types of fish, 500 types of mammals, 1500 types of birds, and 3 million types of insects are found in this zone.

Morpho butterfly, sloth, jaguar, opossum, howler monkey, Julia butterfly, monarch butterfly, green anaconda, iguanas, poison frog, electric eel, piranha, antelope, bonobo, gorilla, tree swift, leaf bird, fairy- bluebird, wood swallow, hornbill, macaw, spider monkey, orangutans, coral snake, bushmaster, etc. are noticeable here.

Also, some tiny animals are seen on the ground in this forest, they are called Cryptozoic. Stratification can also be observed in the animal groups living in the rainforest region. These are

1. First layer

A variety of birds, butterflies, bats, etc. reside above the highest layer of evergreen forest. These animals can fly extremely fast. Eagle, swiftlet, etc. are found in this layer.

2. Second layer

The tallest trees in this forest form the canopy layer, home to a variety of animals. Some small animals such as squirrels, morpho butterflies, sloths, jaguars, opossums, etc. are also observed here.

3. Third layer

Some insects, birds, and mammals are found in this layer.

4. Fourth layer

Animals living in this layer are highly skilled in tree climbing. They can climb to the highest level using tree trunks, ranches, etc. Herbivores and carnivores both these types of animals are both observed in this layer.

5. Fifth layer

Most of the animals living in this part are large herbivores. Some birds are also seen. Although these animals are large in size, their bodies are flexible so they can easily enter dense forests. But these animals are not adept at climbing trees.

6. Sixth layer

Small animals live in these layers (1) & (4).

Microorganisms

There are some types of microorganisms found in the tropical rainforest. These are acidophilic bacteria, actinomycetes, mycorrhizae, actinoplanes, blue-green algae, coral fungus, organ pipe fungus, etc. are different types of microorganisms are noticeable here (2).

• Plant species are the producers of tropical rainforest regions.
• Animals species are the consumers &
• Microorganisms are the decomposers of the tropical rainforest. All these biotic factors in the tropical rainforest depend on each other to form the rainforest ecosystem. 

Q&A

1. What biotic factors are in the tropical rainforest?

Living factors of the environment are identified as biotic factors. Biotic factors of tropical rainforests are animals, plants, insects, reptiles, amphibians, fungi, and microorganisms.

2. What are the biotic factors in the rainforest?

Rainforest regions are rich in biodiversity. So there are various types of biotic factors noticeable. These are different types of plants (rosewood, mahogany, ebony, orchids, philodendrons, etc.), animals (jaguar, sloths, gorillas, etc.), insects (morpho butterflies, bullet ants, etc.), fungi, bacteria, etc.

3. What animals in the tropical rainforest?

The green anaconda, toucans, gorillas, okapi, sloths, jaguar, harpy eagle, spider monkey, orangutans, hornbill, macaw, western lowland gorilla, chimpanzee, scarlet macaw, large flying fox, hummingbirds, lemurs, glass frogs, etc.

4. What are three abiotic factors in the tropical rainforest?

Abiotic factors are the nonliving things of an environment. Topography, rainfall, and temperature are three abiotic factors in the tropical rainforest.

5. What are some biotic factors in the temperate rainforest?

Some biotic factors in the temperate rainforest are moss, birds, animals, trees, insects, and bacteria. They are the living parts of this region.

6. 3 biotic factors in tropical rainforests?

Producers (plants), consumers (animals), and decomposers (microorganisms) are 3 biotic factors in the tropical rainforest.

7. How many animals in the tropical rainforest?

About 3500 types of fish, 500 types of mammals, and 1500 types of birds in the tropical rainforest.

Written By: Manisha Bharati