56 



MAN ON THE LANDSCAPE 



That they do have such limitations is common knowledge. Just how 

 the plant will react when one of the above factors changes, or the 

 plant is placed in a different setting, is difficult to determine, except 

 by trying it. Some plants are finicky, others flexible. Furthermore, 

 changing one of the environmental factors may result in changes in 

 others. Altering soil acidity by adding lime may increase the fertility 

 for some plants; it may make the soil more granular and absorbent, 

 thus actually increasing the effectiveness of rainfall, and altering the 

 "little climate" in which the plant lives. 



Environment is so closely related to life that a knowledge of its 

 development is needed to understand the world today. 



FIG-. 18. A road cut exposes the earth's rock mantle. The thin layer of top- 

 soil 'is seen, lying* on several feet of subsoil which shades into the parent rock. 

 In your mind, roll the rngr of topsoil off the landscape, notch the subsoil with 

 rullies and you have elemental badlands, barren of all but the simplest forms 



of life. 



1 





. 



-yfrmg 



*m.+? 



*' "icaf ift^HK'i 



