62 PKIKCIPLES OF AMERICAK FORESTRY. 



the cultivated forests, unnece^ary crowding is prevented 

 by judicious thinning, and the land is kept evenly and com- 

 pletely stocked with the most profitable kinds. 



Succession of Tree-Growth is an expression sometimes 

 used as though there were a natural rotation of trees on the 

 land. There is nothing of the sort. Sometimes hard 

 woods will follow pine, or the pine the hard woods, where 

 the two were mixed at the time ^f cutting and there 

 was a young growth of one or the other kind which had 

 a chance to grow when its competitor was removed. Where 

 land is severely burned after being cut over, the trees 

 that show first are generally the kinds with seeds that 

 float long distances in the wind, such as Poplar and Birch, 

 or those having fruits especially liked by birds, such as 

 the Bird Cherry, which is very widely distributed. These 

 show first on account of getting started first. The Pine 

 and the other trees may come in later owi ng t o their being 

 seeded later, or owing to the later advent of conditions 

 favorable to their germination and growth. It may hap- 

 pen in the case of burnt-over pine land that pine seed is 

 distributed over it the first year after it is burned, but 

 owing to there being no protection from the sun the young 

 seedlings of White and Norway Pine, which are very deli- 

 cate, are destroyed. After a young growth of Poplars 

 has appeared the pine seed may find just the right con- 

 ditions for growth for a few years and finally get ahead 

 of the Poplars and crowd them out, while in the meantime 

 it is being much improved by the presence of the Poplars^ 

 wliich, grow rapidly and force the Pines to make a tall 

 growth. On the other hand, however, the Poplars, Birches, 

 and other trees and shrubs and even weeds may sometimes 

 make so strong a growth as to kill out the young Pine 

 seedlings iLtSey are not sufficiently well established at the 

 time the mature. growth is cut. 



Regeneration is a term commonly used in forestry to 



