10/10-10/11

We are starting the unit on the rainforest. This is the first assignment. It is due Wed. The questions are embedded in the reading.



What are TROPICAL RAINFORESTS? Rainforests 101
The tropical rain forest is the greatest expression of life on earth. - Dr. Thomas Lovejoy-A leading rainforest expert

Directions: A. Answer on your own paper.
B. Write your answers in full sentences.

Tropical rainforests are not just a bunch of trees. Rainforests are a complex relationship between plants and animals that depend on one another in numerous and many times unknown ways. If one link is removed, the whole balance of the system can be dramatically changed and often not for the better.
Rain forests are forests that are found near the equator in the tropic zone. They are found in North America, South America, Africa, Asia and Australia. In these forests, it is warm all the time, and rainfall is abundant and constant.
Rain forests cover about 6% of the surface of the earth. That is about as much area as the lower 48 states. They have some features that are quite similar everywhere, no matter which continent they are on.

Q1. How large an area is 6% of the earth?

A tropical rainforest will have these conditions:

1. Rain forests have lots of rain. They don’t call it a rain forest for nothing. Rain forests get over 60 inches of rain a year. Some places have recorded over 400 inches! That is averaging more than an inch of rain every day for an entire year.

2. Rain forests have lots of heat energy. Because rain forests are located near the equator, they have warm temperatures all year long. Places near the equator get more solar energy than other places. It is estimated that a square inch of land near the equator will get twice as much solar energy as a place in the temperate zone.
There is very little seasonal change in temperature in rain forests. It doesn’t even change much between day and night. That means the temperature doesn’t ever change much. The temperature will be nearly the same in December as it is in July. The average temperature is around 80º. There is never any winter with snow or frost, like in Wisconsin.

Q2. Why do plants grow so well in rainforests?

3. Rain forests have the greatest amount of biodiversity in the world. The constant rain and heat are the perfect conditions for plants to grow. The humid conditions make it a virtual plant paradise, like a giant greenhouse. Because so many plants thrive there, animals that eat plants live there in abundance too. Animals that eat the animals that eat the plants then are common. Life is everywhere.
If a place has a lot of biodiversity it has many different kinds of life or species. A species is a group related organisms with common features that can reproduce and create new members of that species. Jaguars are a species. So are pink river dolphins. Scientists figure that half or more of the plant and animal species that are in the world can be found in the rain forest. Researchers have figured out that the more biodiversity a place has, the fewer members of that species there are. For example, the rain forest has many different kinds of butterflies but very few of each kind. Going to a rain forest is very cool because there are so many different things to see, but having very few of each kind can be problematic. If the rain forest is destroyed, having a few of each species makes it easier for that species to become extinct than if there is a great number. Many plant and animal species have yet to be discovered in the rainforest. The fear is that they could become extinct before they are even known.

Q3. What is it like in a place that has a lot of biodiversity?

Q4. How many of the world’s species live in the rain forest?

Q5. Why is destroying the rain forest a problem for it’s biodiversity?

4. Rain forests have poor soil. Many people look at a tropical rainforest and make the seemingly logical conclusion that the soil is wonderful because of the abundance of plant life. But the topsoil is very thin because of the heavy rains. Many times the topsoil is only one to three inches deep. The rains wash away the soil and nutrients in the soil the plants need to survive.
Rainforest plants survive by having their roots run shallow along the top of the soil. The leaves fall from the trees, leaving a carpet of leaf litter on the forest floor that is constantly in a state of decay. Soil is essentially decayed and decomposed plants and animals with bits of rock and sand material mixed in. The hot, wet, humid conditions causes the leaves to decompose very quickly. The surface roots suck up the nutrients from the newly rotted leaves before the rain can wash all of them away. Basically the plants feed themselves in a constant cycle of decay and growth.
Rain forests are very complex ecosystem that we are just beginning to understand.

Q6. Why is rain forest soil so thin?

Q7. Make a list of ways you think forests in Wisconsin are different than tropical rain forests.