4o8 How Living Things Affect Ojie Another unit vii 



because our continued existence depends in which we disturb plant-animal rela- 



on our ability to do so. Conservation tionships: by destroying organisms; by 



really attempts to maintain normal rela- providing conditions which make it pos- 



tionships which have been disturbed by sible for other species to increase at a 



our civilization. Closely related to keep- great rate; and by importing plants or 



ing normal relationships among living animals which, without their native ene- 



things is conservation of soil, without mies, increase very rapidly. Each disturb- 



which we could not obtain sufficient ance of normal relationships may create 



food. You must remember all the ways a new problem for us. See Exercise 5. 



Questions 



1. State some of the many uses of forest trees to us. State two important 

 causes of the destruction of forests. 



2. Explain an important indirect result of forest destruction. 



3. If we are to have forest conservation what is the limit on the number 

 of trees one may cut each year? Which trees should be selected for 

 cutting;-? 



4. What is meant by topsoil? Describe three practices which lead to 

 destruction of topsoil. 



5. Name three methods of saving the soil. 



6. Explain contour plowing and planting. 



7. Explain sheeting. What is meant by a cover crop? 



8. Explain three ways by which farmers may restore fertility to soil. 



9. Name four animals that we have destroyed. 



10. What steps have been taken to conserve wild plants and animals? 



11. Describe two important lav.s designed to conserve wild animals. If 

 animals are being killed off too fast by hunters or fishermen, what laws 

 can be passed to protect them? 



12. Why is conservation so important? 



Exercises 



1. Suppose that you were the director of a lumber company that 

 owned vast stretches of forest land. What regulations would you issue to 

 prevent forest fires on your land? What fire-fighting training would you 

 give your employees? See Figure 353. 



2. By class discussion, plan a biological survey of a small field or city 

 lot near your school. Which facts will \'ou need to know about each ani- 

 mal and plant? If the season permits, carry it out. Prepare a scientific re- 

 port of the work. 



3. Divide the class up into committees and obtain information about 

 organizations that help to maintain normal plant-animal relationships. In- 

 clude the U.S. Fish and Wildlife Service, the U.S. Forest Service, your 

 State Department of Conservation, Fish Hatcheries, the American For- 

 estry Association (Washington), Friends of the Land, and others. 



