We have a new assignment. It is called What are the Four LAyers of the rain forest. It is due on thursday. Students will have at least 30 minutes to work in class. I am emphasizing complete sentences.
What are the Four Layers of the rain forest?
Directions: A. Answer on your own paper.
B. Write your answers in full sentences.
Rain forests have been described as having four layers. Did you know that a woods or forest near you has layers too? After reading about the four layers, look at a wooded area near your home and see if it looks like it has layers. Let’s start at the top.
Emergent Layer
Emergent means to stick out above. The emergent layer is the giant trees that stick out above all the rest. Emergent trees can be 150 feet tall or more. There aren’t very many of these, usually only one or two per acre. The kapok tree is probably the most famous emergent tree.
The emergent layer is windy and bright with sunshine. These conditions are very different than the other layers, so the emergent trees are different than the typical trees of the rain forest. First, they have very small leaves. It’s funny, the biggest trees have the smallest leaves. There is a good reason for this. The emergent trees have the full force of the wind. There is nothing to block the breeze from the leaves. If the leaves were large, the wind would catch them like a sail. This could rip them right off the tree. The wind can also rob a tree of its moisture by blowing on its leaves. The wind does not dry out small leaves as much.
The emergent layer has very few animals living there. Insects would be found crawling on some branches, but most larger animals will not go there. Predators, like the magnificent harpy eagle, make their homes in the high emergent trees. Hunters, like the eagle, often have very good eyesight. They sit in the tall trees and watch below. Any animal that ventures out of the hidden mass of branches can become an eagle’s lunch. Many animals instinctively avoid open areas where they can be seen.
Q1. How is an emergent tree different than a regular tree?
Q2. What 2 weather conditions do all emergent trees have?
Q3. Why won’t many large animals go into the emergent layer?
Canopy layer
A canopy is a covering put above an object as a shelter. The canopy of the rain forest is like its roof. It is a tangle of leaves and branches from hundreds of trees. It is generally 60 to 120 feet above the ground.
The canopy blocks the sunlight from reaching the floor of the forest. Most of the blocked sunlight is captured by the leaves for photosynthesis so the plant can make energy to survive. The energy from the sun that is stored in the leaves is also used as food by animals that eat them. The canopy is like the grasslands of the rain forest. Just like the prairies of North America could sustain huge herds of bison, the canopy leaves support huge populations of animals. Some estimate that 80 to 90 percent of rainforest animal life lives in the canopy. Scientists didn’t realize this until recently. Once this was figured out they had no way to get up in trees and study the organisms there.
Q4. What does the word canopy mean?
Q5. Why do most of the animals of the rainforest live in the canopy?
Very little light gets past the canopy for the plants on the lower levels. So to get light, some plants have developed an adaptation to survive. Instead of trying to grow in the shade of these trees, they have ways to actually grow on the branches of the canopy trees where they can get some sun. Plants that grow on other plants are called epiphytes.
Epiphytes live their entire life up in the treetops. Their roots are attached to a small mat of decomposed plants on the branches, which works like a thin layer of soil. The epiphytes get nutrients from that mat. Many epiphytes also have air roots that hang down and collect microscopic beads of water vapor in the humid air. Other plants, like the bromeliad, have thick spiky leaves that go around in a spiral and forms a cup that fills with water. The water is stored in this space and used by the plant to survive. A pineapple is a bromeliad. Look at its top and you get the picture of what a bromeliad looks like.
Epiphytes are where all the action is in the forest. The leaves of the epiphytes are hiding places, homes, and food for a multitude of animals. One study found 250 species of animals lived or depended on one bromeliad epiphyte! Dozens of animals use the stored water of epiphytes for drinks and then there are predators that wait for the thirsty. Tree frogs and insects, like mosquitoes, lay their eggs in the water. It is a miniature community that is rarely ever witnessed because it takes place 90 feet above the ground.
Q6. How do epiphytes get sunlight to survive in the dark forest conditions?
When the rains come, the canopy of leaves works as an obstruction to slow the hammering rain. By the time the rain bounces off hundreds of leaves and branches, it is merely a trickle instead of a pounding force. If the trees were removed, the fierceness of the continual rains would not be slowed by the canopy, and the rain would dig up the ground like a plow and begin to wash it away.
Understory layer
The understory is all the small trees and shrubs that are under the canopy. It includes the tree trunks of the canopy trees. Many times it looks like the small understory trees reach to the bottom of the canopy making it difficult to see where one layer ends and another begins.
The understory doesn’t get much wind or light. It also doesn’t have many animals. It is described as the highway animals use to reach the canopy. Unfortunately, it is the section of the rainforest that is most easily visible to the tourist: tree trunks.
Q7. Describe the understory.
Forest Floor
Us humans spend a lot of our time examining the forest floor. The floor is the dead leaves that have fallen and very small plants. The floor is very important to the survival of the forest. The dead leaves quickly decompose into soil that helps feed the great trees. It provides the nutrients for the plants to suck up in their roots. The floor has no wind, gets very little, and is warm and humid. These are the perfect conditions for things to rot. The powers of decomposition are swift. It has the rich earthy smell of a compost heap.
Q8. What are the conditions that cause things to rot?
A giant tree may have roots that are only 24 inches deep. Tree roots in the rain forest are on the surface because the soil is so poor and thin. There isn’t anything good for them any deeper. Trees in Wisconsin have roots that go down nearly as deep as the tree is tall.
The tree’s roots are very important. Roots of plants suck up water and nutrients from the soil. Plants need those nutrients just like you need healthy foods to grow. The roots of plants do more than hold the plant up and suck up water and nutrients. They also hold the soil in place so it doesn’t wash away. If the rainforest plants are gone, erosion happens very fast and is very damaging.
Q9. Name 2 jobs tree roots do.
A healthy forest has very few plants on the forest floor because it receives so little light. It is actually quite easy to walk around. It is estimated that only 2% of the sunlight hits the floor. Plants that do live here must be able to live in the shade. Many green plants have developed huge leaves to capture any sunlight that gets through the canopy. Forest floor plants have become our houseplants because they can grow well in the shade of our homes.
Because the floor is dark this is where fungus grows. Fungus is a plant that doesn’t need sun to live. They get their energy by decomposing dead material into soil and usable nutrients. This makes fungus very important to the survival of the forest. A mushroom is an example of fungus and a wide variety of forest fungi flourish in the rain forest.
Q10. Why do healthy forests have few plants on their forest floor?
The forest floor has some animal action in it, but it doesn’t hold the mystery and imagination of the canopy. Many insects live in the leaf litter. The easiest to find are ants and beetles. They are everywhere. Beetles are the most common insect species on the planet. Some small animals live on the forest floor. Rabbit-sized rodents like agoutis and pacas scurry around in the litter. Large predators are rare, but the jaguar does look for prey here. Snakes can be seen hunting on the floor. Most snakes are actually nocturnal, so seeing one during the day is not that easy.
If you live by a forest or even a clump of woods you will observe many of these same characteristics. There will be layers, a few epiphytes and plants that grow better in the shade. Fallen leaves will be going through the process of decomposition and turning into soil and nutrients for the surrounding plants. Check it out.
Q11. Label the layers of the rainforest.
