a Costa Rican cloud forest

 The Rain Forests of Costa Rica and Washington

a rain forest in Washington
 
Written in 1997, when I was in 7th grade
 

Rain forests cover only two percent of the land mass of Earth, yet they harbor more than 50 percent of the species of plants and animals in the entire world.

And rain forest trees are being cut down at a rate of 100 acres per minute. At first glance, you think, "Wow, that's a lot, that's too bad." But once you learn about the incredible diversity of plants and animals and the amazing amount of life in old-growth rain forests, you will realize that 100 acres per minute, more than an acre per second, is more than "a lot" and more than "too bad."

Rain forests used to cover most of the world. Today, tropical rain forests cover only two percent of earth's land mass, and temperate forests cover only 0.2 percent (of which two-thirds are on the Pacific Northwest coast of North America).

Millions of species of wildlife live in a tropical rain forest. In Costa Rica, the diversity is especially rich because species from North and South America have come there. As you walk, everything around is different. You "might pass one tree species and not see another for half a mile" (Christopher Baker). In temperate forests, though, much of the forest has the same kinds of plants and animals, making much of it seem the same.

The only way in which temperate rain forests outnumber tropical rain forests is the living biomass. Forests in the Northwest have 500 tons per acre, and tropical rain forests have only 300. On the west side of the Olympic Peninsula in Washington State, which gets more than 120 inches of rain, the productivity rate is higher than anywhere else on earth. Things grow everywhere-on the ground, rocks, riverbanks, and trees.

Both kinds of rain forests have distinct layers: the main ones are the canopy, understory, shrub layer, and floor. There is life on all levels, and many species spend all or most of their time in just one layer. This also results in more species, for example, instead of having one kind of beetle that lives all over a tree, there can be a different kind of beetle for each layer.

Also, in tropical rain forests, there are literally two climates: above or on the canopy, and below it. Underneath the canopy, the climate is hot and humid (90% humidity) for all 24 hours of the day. But on top of the canopy, breezes carry a lot of the moisture away, sometimes lowering the humidity to 60 percent, and the temperature changes 15 degrees from day to night. The floor is relatively open because only ten percent of the sunlight actually reaches it.

Often, one will walk through a tropical rain forest and hear all sorts of birds, monkeys, and more. But where are they? Almost everything is in the canopy, 300 feet above the forest floor. The ongoing battle for light has pushed everything up into the canopy. Half to three-quarters of the rain never reaches the ground. Nutrient-filled soil is in every crack, and there are even puddles suitable for tadpoles. Large cats like jaguars have adapted to spend their whole life in the canopy, jumping from branch to branch.

So what is it that makes tropical rain forests so different from temperate rain forests? In some ways they're the same: they both get a high amount of rainfall, they both have a lot of epiphytes (plants that live on other plants), and many other things. But they also have some big differences. In a tropical rain forest, nearly all of the life is in the canopy, and there is much more diversity than in a temperate forest.

The main reason is that a tropical rain forests gets sunlight throughout the year, but temperate gets mostly clouds and fog. So the trees and life in a temperate forest haven't fought as much to get to the sunlight. Instead, they have to try to make do with a small amount of light.

Also, though not too noticeable, temperate forests have seasons, so nutrients are used in "protein surges" where protein is used up in spring, falls to the ground as leaves, nuts, berries, etc., then sucked up again the next spring. In tropical rain forests, protein is constantly being sucked up, and the fact that everything is so eager to get nutrients speeds it up. A fallen leaf takes no more than a month to fully decay before trees suck up the nutrients and the cycle starts again.

Rainforest Plants

Intro | Plants | Animals | Conclusion | Bibliography