124 THE HUMAN SIDE OF TREES 



tions failed to find any specimens of this tree in 

 Kansas and Nebraska, states where it is now quite 

 common. In many parts of the country second 

 and third growth trees are entirely unrelated to 

 the original timber. The Catskill Mountains of 

 New York when first visited by white men were 

 largely covered by spruce and hemlock. Such areas 

 as have been cut over have nearly always been 

 taken possession of by beech, maple and birch. Of 

 late years it has been noticed that poplars and 

 aspens show a strong disposition to grow up in 

 abandoned clearings. By noting the tree species 

 on a particular piece of woodland, a person familiar 

 with the Catskills can usually tell whether it is 

 first, second or third growth. 



This is a striking example of the selective power 

 exhibited by the trees in choosing where they shall 

 live. Some authorities claim that the trees have es- 

 tablished a natural rotation of crops. When the 

 pines and the spruces have exhausted the surface 

 soil with their wide-spreading roots only a few 

 feet under ground, the oak comes along and, with 

 its deep-travelling nutriment-suckers, taps the 

 lower-hidden food supplies. By the time the sturdy 

 acorn-bearer has become old and grey and de- 

 scended to the grave, the once impoverished sur- 

 face-soil has recouped itself with many generations 



