METHODS OF CONSERVATION 369 



Man^s Need of Conservation. — Man's domination of the 

 civilized world has meant, as he multiplied, the necessity of more 

 food, more water and better water supplies, more power to light 

 his cities and run his machines, more fuel, and in fact more of 

 everything necessary to his complex life. The balance of nature 

 has been disturbed by man in his ever increasing demand for food 

 and other supplies. In consequence, he must learn how to con- 

 serve the supplies so necessary to him. It is certainly the place 

 of a course in Civic Biology to show the average citizen how and 

 why this may be done. 



Methods of Conservation. — Although in biology we are not 

 directly concerned with methods of conservation which deal with 

 our mines or our fuel oil, we are indirectly studying the con- 

 servation of water supplies when we deal with the problem of the 

 protection of our forests. Our national health is the largest 

 problem of conservation with which we have to deal, and some 

 methods have been discussed in earlier chapters. This chapter 

 is concerned particularly with the conservation of useful plants 

 and animals. This gives us two general methods to consider: 

 first, how to protect our useful plants and animals ; second, how 

 to eliminate harmful organisms. 



Methods of Forest Conservation. — Back of all life on the earth 

 are the food supplies made by the green plants. Back of our water 

 supplies and our rich soil lie our forests. We have already seen 

 that the forest is being used more than four times as fast as it 

 grows s and that our forest areas are lessening each year. We 

 already lack hardwoods for trim and furniture and our pulp wood 

 reserves are dwindling rapidly. 



Avoiding Waste. It is evident that we must replant our forests 

 as they are used and plant new areas, and that we must obtain 

 substitutes for some of the forest products, and make use of waste 

 products from the forests. Formerly, lumber companies burned 

 the sawdust and other waste from the mills; now fuel alcohol 

 and other valuable products are obtained from them. It is esti- 

 mated that more than 300,000,00Q gallons of fuel alcohol could be 

 made annually from the wood thus wasted. It is estimated that 

 20% of the timber now wasted might be used in building. Rail- 

 roads use 15% of our timber for ties ; treatment of these ties with 



