506 BIOLOGY FOR BEGINNERS 



exercised in their planting or maintenance. If quick growth and 

 immediate results are wanted, soft maples or poplars are used, but 

 these are short lived and rather easily broken by storms. Elms 

 and hard maples, on the other hand, grow slowly, but are sturdy 

 and live to great age. 



City trees require special protection as they are especially 

 valuable and are not living under natural conditions. Insect 

 attacks can be overcome by proper spraying; damage by horses 

 and traffic can be prevented by guards around the trunks; suit- 

 able laws can be enforced to protect from damage by careless 

 linemen who cut out the tops to pass their wires; sidewalks and 

 curbs can be kept from injuring the roots; and " surgical " treat- 

 ment should be used when rot or injury makes wounds in any part. 



COLLATERAL READING 



Elementary Studies in Botany, Coulter, pp. 419-431; A First Book of 

 Forestry, Roth, entire; Care of Trees, Fernow, entire; Handbook of Trees, 

 Hough, look through; Nature Study and Life, Hodge, pp. 365-391; Prac- 

 tical Biology, Smallwood, pp. 376-388; Principles of American Forestry, 

 Green, entire; Trees of Northern United States, Apgar, look through; 

 Commerce and Industry, Smith, pp. 182-208; Our Native Trees, Keeler, 

 look through; "American Forestry" a monthly periodical. 



SUMMARY 

 Value of Forests. 



1. Control of water supply. 



2. Benefit to soil, humus. 



3. Effect on climate, wind protection. 



4. Home for birds and game. 



5. Forest products (see tabulation). 



Enemies of the Forests. 



1. Man, through careless lumbering, fires, etc. 



2. Insect enemies. 



3. Fungus diseases. 



4. Weather conditions, sleet, frost, snow. 



5. Grazing and other animals. Rodents. 



Protection of Forests. 



1. Laws, enforced and supported by people. 



2. Careful lumbering. 



3. Reforestation, planting, etc. 



