index > Today's Earth, Our Future > 2. Gifts from the forests > Forests are Amazing!
 
Forests are Amazing!
Forests not only provide us with wood and food, but also act as enormous "sponges" or "green dams." Look, the rain has begun! Let's step into a forest. The forest's soil feels soft like a sponge because it's filled with many small cracks that steadily absorb rainwater. On the other hand, the soil in schoolyards is often hard with no cracks. For the amount of rainwater that a schoolyard's soil takes to absorb in 20 minutes, the forest's earth can absorb the same amount like a sponge in just one minute. Amazing, isn't it? Rainwater that has fallen on the forest's soil flows into mountain streams or stays underground (as "ground water"). Depending on the conditions inside the soil, the water may flow quickly into the rivers, while sometimes it takes several hours, several days or even several years. The forest soaks up the rainwater and stores it in the ground or gradually lets it run into the rivers, which help keep them from overflowing even after a torrential rain, and also keep them from drying up, even after several weeks without rain. In Japan, for example, considering that soil is one meter in depth, forests there can store as much as 44.4 billion tons of water, which is the same amount that it would take for about 8,000 middle-sized dams to hold! Now you see why forests are called "green dams," don't you? In forests, the trees and grasses extend their roots in all directions--from thick roots to ones as thin as a strand of hair--which hold the earth and stones tightly together, keeping the soil from flowing into nearby rivers. With the same amount of rainwater, the soil in an area without trees flows 150 times faster than it does in a forest. While dams become useless when earth and stones builds up behind them, forests that are located upriver stop the soil from flowing down riverbanks, acting as "dam protectors." In 1998, the Changjiang River in China had a great flood that killed thousands of people and carried most of the houses away. Since the Chinese government thought that the cutting of 85 percent of forest trees located upriver was responsible for the disaster, they tried to replant the trees. But sadly, the river flooded again the following year. Trees can be chopped down in the blink of an eye, but it takes a long, long time to grow them back into a "green dam." Another important role of forests is to absorb carbon dioxide and change it into oxygen. While it may be hard to see, forests protect us from floods, landslides, wind damage and avalanches, and they also clean our water and air. They are our constant protectors.
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   2. Gifts from the forests
   
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