What is The Soil Type in The Tropical Rainforest?

If you have a green thumb, you must have an interest in tropical rainforests: the type of vegetation that grows there, the soil, the fauna, everything. You might wonder what is the soil type in the tropical rainforest? Let’s have a look.

Tropical rainforest soils are primarily composed of ultisols and oxisols. Although these soils are rich in aluminum oxide and iron oxide–which gives the soil its red color–tropical rainforest soil fertility is actually quite low.

Although you’ll find a lot of vegetation in rainforests, organic matter in the soil is lesser as compared to tropical forests. In this article, we will have a deeper look at the soil found in tropical forests, its features, and the flora it produces.

What is The Soil Type in The Tropical Rainforest?

The primary types of soil in tropical rainforests are Ultisols and Oxisols. Both types of soils are rich in aluminum oxide and iron.

Surprisingly, soil found in tropical rainforests is very poor in nutrients and has low fertility. So basically, the tropical rainforest soil is very poor. 

With all the thick vegetation, moisture, and warmth, you would consider this soil very rich. 

However, the truth is otherwise. 

There are many reasons for this poor soil, and some of them are:

    Nutrients Stored in Plants:

In forests, when dead organic matter falls to the ground, it adds valuable nutrients to the soil. In cooler or drier regions, this nutrient is built up in the soil for new growth. Contrary to that, in a tropical rainforest, the newly added nutrients to the soil are reabsorbed by plants as fast as they are deposited. Moreover, most trees in these forests are evergreen, and very few leaves actually fall onto the ground.

    Poor Soil Ability to Hold Nutrients:

The type of soil particles present in tropical forests has a very poor ability to hold nutrients for longer and prevent them from washing away. Even if you add nutrients to this soil artificially, the high volume of rainfall these forests receive wash them away in no time.

    Rapid Decomposition:

Due to the high temperature and moisture content in tropical rainforests, the dead organic material added to the soil decomposes rapidly as compared to other climates, and thus, nutrients are released and absorbed quickly.

    Humans Destroying Nutrients:

When humans burn rainforests for raising crops or cattle, most of the nutrients in the soil are being burned with the vegetation. This is another important reason for depleting soil nutrients.

If the soil of tropical forests is this poor, how do you find a good amount of shrubs and trees growing there?

Well, you’ll find the answer above the soil. 

On the ground, there is a layer of quickly decaying animals and plants. 

Most nutrients from these sources are washed away by heavy rainfall without allowing them to enter much in the soil.

Soil Types in The Tropical Rainforest

Usually, the soil in tropical forests is several meters deep. 

However, this soil is often leached or washed out, and a large number of nutrients and minerals are removed from the subsoils. 

It also breaks down rocks to produce soil. 

The leaching process for millions of years has left the soil with no to too little number of some of the fundamental nutrients required by plants.

The primary types of soil in tropical rainforests are Ultisols and Oxisols. Both types of soils are rich in aluminum oxide and iron.

The topsoil of these regions holds a huge amount of carbon that has a major influence on carbon dioxide levels, and thus, an important potential influence on climate change.

Due to deforestation on a large scale, tropical rainforests do not occupy more than 0.3% of the land surface on Earth. 

Topsoil plays an important role for all plants–no matter if they’re in forests or at home. 

For houseplants, check our top soil for houseplants: 4 common problems & which soil to use.

Temperate Rainforest Soil Type

The temperate rainforest soil is fertile. Usually, this soil is dark and damp. 

The dampness of soil is mainly due to the moisture and high amount of rainfall, whereas, the darkness is due to trees shading the sunlight. 

The fertility of temperate rainforest soil is a result of dead organic material on the forest floor that is being decomposed by insects, bacteria, and fungi.

Typically, the temperate rainforest soil consists of:

  • Andisols – formed by the deposit of volcanic ash
  • Spodosols – mainly sand
  • Alfisols – soil with a clay-enriched horizon.

Rainforest Carnivorous Plants

Most carnivorous plants are found in areas that have abundant water and sunlight but have a low amount of nutrients in the soil–especially nitrogen. 

With an incredible adaptation, they are able to trap and digest small animals and insects. 

Carnivorous plants have bright-colored leaves and sweet nectar that attract their prey, and once they arrive, the plant traps them. 

To trap their prey, plants leaves several tactics:

    Adhesive Traps

The plants that use adhesive traps usually have special glands on the end of their leave stalks that produce a sticky substance to trap small insects. Sundews use this technique to grab food.

    Suction Traps

For this technique, plants have bladders covered with lids or trap doors. As soon as an insect touches this trap door, it is sucked into the bladder and digested. Bladderworts use its suction trap to get food.

    Pitfall Traps

Plants like pitcher plants use this technique to trap their prey. They have a pool filled with enzymes, and when a prey slips in it, it gets digested.

    Snap Traps

Some plants have leaves that snap shut when their trigger hair are touched by more than once. Venus flytrap plants use this way to capture their food.

Some common carnivorous plants found in tropical rainforests are:

●     Genlisea

●     Venus flytrap

●     Pitcher plant

●     Bladderworts

Rainforest Plants and Flowers

More than two-thirds of the plant species are found in the tropical rainforests

These plants not only provide food for animals found in the region but are also the largest contributor to the world’s oxygen supply.

Flowers of tropical rainforests are adapted to hot and humid climates. 

These forests are home to exotic flowers and carnivorous plants found there can be up to 30 feet.

The main type of plants and flowers found in tropical rainforests include:

●     Rubber trees

●     Cacao

●     Passionflower

●     Queen’s tears

●     Monkey brush vines

●     Kapok tree

●     Bromelia

●     Orchids

Orchids are beautiful flowers that can grow in different conditions. 

If you want to add a colorful addition to your garden, you can check how to grow orchids in a greenhouse.

Rainforest Fruits

Tropical rainforests produce a wide variety of fruits. 

According to an estimate, there are more than 3,000 types of edible fruits are grown in tropical rainforests alone. 

In these forests, thousands of different types of fruits grow, many of them are not known by people.

 Some of the common fruits found in most rainforests are:

●     Figs

●     Bananas

●     Oranges

●     Dates

●     Lime

●     Avocadoes

●     Passion fruit

●     Grapefruit

The uncommon fruits include:

●     Kumbu or bacaba

●     Strawberry guava

●     Camu-Camu

●     Jagua

●     Acai palm berry

●     Buriti

Strawberry guava is a common fruit found in many areas of tropical rainforests. This fruit tastes just like strawberries and is often used to make jams.

There are many other fruits as well. Many of these fruits are used by locals in different forms for various purposes. 

Some of these fruits also have medical benefits and people have been using them for treating specific health issues.

Note: if you want to see your strawberry plants thrive in your garden, check out how to keep slugs from strawberries.

Rainforest Ferns

Ferns are a type of plant that is known as epiphytes. 

These plants thrive best in rainforests. 

They can easily grow on other plants but do not harm them.

The leaves of ferns look like feathers and fans. Almost all ferns do not produce flowers, fruits, or seeds. 

Instead, they reproduce through spores.

As many plants have been living on our planet for millions of years, ferns are here for much longer. 

Scientists believe that they were present even 325 million years ago.

Tropical Rainforest Ferns

Ferns have adapted to tropical rainforests, and the main adaptation is the presence of a rhizome. 

It grows horizontally just beneath the ground that allows it to absorb nutrients easily. 

There are more than 40 fern species found only in the tropical regions.

Some common ferns found in rainforests are:

●     Staghorn fern

●     Golden chicken fern

●     Bird’s nest fern

●     Rebecca’s tree fern

●     King fern

●     Gristle fern

●     Elkhorn fern

Conclusion

Tropical rainforests have a hot and humid climate and are found near the equator of the Earth. 

Despite the poor fertility of tropical rainforest soil, the combination of abundant moisture and constant warmth throughout the year make these forests a suitable home for many exotic plants and animals.

Tropical rainforests are in the news for many reasons around the year. 

One of the major concerns about these forests is the issue of deforestation that also results in severe damage to the soil. 

f you analyze the situation from the soil’s point of view, the cutting down of tropical rainforests interrupts the natural cycle of soil-plant making the soil highly vulnerable to erosion and loss of the most important topsoil.

About the author

Greg Volente

Greg Volente holds a Naturalist Certificate from the Morton Arboretum, worked for The Nature Conservancy leading environmental education programs and doing natural areas restoration, and worked in the soil science research & testing lab at Michigan State University. Besides gardening, he's an avid wildflower enthusiast, and loves botanizing, hiking, and backpacking.

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