This tree that Jamie’s climbing, is called a strangler fig. Once, there was another tree inside it. These trees are amazing to see – they can grow to 150 feet tall.
The way they start growing in the forest is pretty remarkable, too. A strangler fig doesn’t grow up from the ground, like most trees grow from seeds that sprout in the dirt. It actually grows down, from up above in the rainforest canopy.
To understand how the strangler fig grows, it’s helpful to understand the layers of the rainforest.
Layers of the Rainforest
On the bottom is the forest floor, where many plants grow and animals live. Leaves, fruit and branches fall to the forest floor, where they decompose and eventually become dirt.
The next layer is the understory, where small trees and shrubs grow. Little light reaches here, because of the trees overhead. Some understory plants have huge leaves, to help them absorb more light. Most plants here grow to a height of only 15 feet or less. Only a very few grow to become part of the canopy.
The canopy is formed by the tops of tall trees — like a big green umbrella over the top of the rainforest. Trees in the canopy are often a hundred feet tall, and absorb lots of light. This solar energy creates a rich source of food, such as leaves and fruits, for the huge variety of mammals, birds, insects, bats, frogs and lizards who live in the canopy. Many living things are only found in the canopy and never on the ground!
And finally, emergents tower over the top of the forest. They’re the few trees that grow taller than the canopy, and can grow as high as 250 feet.
This diagram is from the Needham, Massachusetts K-12 website.
The strangler fig: an epiphyte in disguise
The strangler fig has come up with some clever adaptations to help it compete for sunlight, water and nutrients. It starts as an epiphyte, high in the rainforest canopy.
Epiphytes are plants that grow on top of other plants, like this one:
Epiphytes don’t harm the tree, or take anything from it. They get all the nutrients they need from the air, water and sunlight. Some trees are covered with epiphytes — large trees can hold as much as one ton of epiphytes.
The strangler fig sprouts from a small, sticky seed, which gets to the canopy in the poop of an animal such as a monkey, bird or bat that has eaten the fig tree’s sweet fruit. It grows upward and develops leaves, to take in sunlight.
Unlike an epiphyte, however, the strangler fig also grows downward, and puts roots into the ground. To do this, it wraps itself around the host tree. Because it puts roots into the soil, the strangler fig is called a hemiepiphyte.
This is when the fig stops being a harmless epiphyte. The fig wraps itself around and around the host tree, so much that the host tree can’t get the sunlight and other nutrients it needs to survive. It looks like the host tree is strangled.
The host tree dies and decomposes or turns back to dirt, leaving a strangler fig much like the one Jamie climbed. That’s how it gets its strange shape – by growing around and eventually killing another tree. You can see in the last photo Jamie climbing down the inside of the strangler fig, where the original tree used to be.
Although it isn’t very nice to the host tree, the strangler fig is an important home and source of food to many rainforest creatures. The fig tree is called a “keystone species” because it is so important.
During some parts of the year, the fig is the only tree producing fruit, so some animals depend on it as their primary food source during this time. In some forests, as many as 70 percent of the animals depend on figs as part of their diet. Figs produce fruit not just once, but several times a year.
Many creatures also make their home in the strangler fig’s many nooks and crannies, including bats and other small mammals, reptiles, amphibians and birds.
1. Can you name the different layers of the rainforest? There are four.
2. What is an epiphyte?
3. Why are strangler figs important to the rainforest? What do they provide?
4. Have you ever eaten figs? (How about Fig Newtons?)
5. Why do you think the strangler fig got its name? Is it good or bad, or both? Why?