| The study of ecology is important for
everyone who cares about our world. Air, water, and land -- we would not live
without any of these. But what do we mean by land? It is the earth beneath our
feet, wherever we are. It is mountains and plains. It is wide fields for growing
com and wheat. Or it may be an airfield or a parking lot or a highway or a whole
city -- land covered with cement, asphalt, and buildings. Land is the solid part
of the Earth. Land is the soil plants grow in. That is the most important things about the land -- it is the place where green plants grow. Without green plants there would be not life on Earth. Green leaves make oxygen. All of us -- ants, elephants, people, every living creature -- must have oxygen to stay alive. We breathe in oxygen and our bodies use it. Carbon dioxide is formed in the process and we breathe it out. Leaves use carbon dioxide along with water to make food for plants. Then they give off oxygen. This process has been going on for millions of years. It is part of the pattern of our natural life on Earth. This pattern had changed very little for millions of years before people arrived on Earth. People found ways to improve their lives by changing nature, by trying to make nature fit in with their way of life. Warm houses in winter, electric lights at night, factories to produce our food, our clothes, our gadgets(零用品) -- all this people have accomplished. And we learned to grow more food on the land than nature could grow without our help. All this is good -- up to a point. But it has gone too far. We have produced too much and we have failed to see what this was doing to our world. We have not understood the ways in which all living things on Earth depend on one another. We ourselves have increased until the sheer numbers of people on Earth have upset the balance of nature. |