104 MAN ON THE LANDSCAPE 



sibilities of research and invention. Commerce and industry do their 

 best not to disappoint. 



There is a serious question, however. How long can this high level 

 be sustained? 



In the case of vegetation there appears to be a definite ceiling on 

 the per acre yield which land can sustain over a long period of time. 

 It is set by the nature of plants and by the practical difficulties of 

 returning fertility to the soil. Periodically, science gives agriculture, 

 forestry, etc., a shot in the arm which should raise the ceiling. But, 

 in practice, these advances usually serve only to offset previous de- 

 clines. 



The history of past cultures has in many cases been this : There 

 was a rise in living standard, which was sustained for a time, even 

 a few centuries perhaps, followed by a disastrous fall. This is the 

 exploitative cycle. It has been reproduced on a small time scale in 

 hundreds of American communities. Ghost towns are its evidence, 

 and abandoned logging camps, abandoned farms, abandoned factories. 



Sustained yield is the only principle on which a permanent social 

 order can be built. The level of organic consumption may be re- 

 vised slightly up or down from time to time, up if scientific advances 

 permit, down if deterioration of climax conditions appears. 



Altering the Landscape. Man is the dominant life form of the 

 earth ; no other can compete with him in a short-term pitched battle. 

 His tools, chemicals, weapons, and intellect make him supreme. Yet, 

 the total environment can out-endure him, out-survive him in a con- 

 test. At the end of such a contest man will be gone ; but, environment, 

 scarred and wrecked, will remain to lick its wounds and recover. 

 When and if man returns he should be wiser, more friendly, more 

 cooperative. Environment is man's master, but can be made his 

 partner. 



When man approaches the landscape with the intent of altering 

 it, he should keep a principle in mind : 



The maintenance of maximum plant productivity requires that 

 changing the climax vegetation must not debase the fundamental 

 reactions of the environment. 



To ignore this dry statement is to deny the cumulative evolution- 

 ary progress of millions of years. To ignore it is to assume that 

 Nature, or God, as you please, has been wasting time since the earth's 

 beginning. To ignore it is to say that there is no relationship between 

 the earth and life. 



How can such reactions as soil formation, maintenance of fertility, 

 prevention of erosion, and good soil structure be retained? Let us 

 state a few principles. 



1 If the climax preserved a year round vegetative or humus 



cover on the soil, man's cropping system must do likewise. 

 2 If nature returns humus into the soil, man must return humus. 



