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required but where natural regeneration is used one may find 20,000 

 or even 100,000 seedlings per acre. If we go into a mature forest 

 stand and count the trees per acre we will find probably 150, or some- 

 times 250, and occasionally 400 ; hence, we must conclude that a large 

 proportion of the trees which start out cannot survive. Two ques- 

 tions suggest themselves: What happens with the large number 

 of trees which cannot mature? Why is it necessary to plant so many 

 when only a small number can mature ? If one inspects a plantation 

 of trees a few years after it was established he will be able to note a 

 difference among the trees. Some are thrifty, which is shown by 

 their rapid growth, others are average, while still others show no 

 signs of growth whatever or may have died. If one returns ten years 

 later this condition is still more pronounced. By this time they 

 will have grown to such dimensions that their branches are beginning 

 to interlace. A struggle has started between them. There is no 

 longer sufficient space for all of them. They must battle with each 

 other for light and food. Some will conquer and be known as domin- 

 ant trees, while others will just about hold their own and be known 

 as intermediate trees, while still others will be conquered and be 

 known as suppressed or dead trees. This struggle for existence is 

 found in all places where trees grow in the form of a forest, and re- 

 sults in the elimination of the weaker specimens. At the same 

 time it gives such drastic discipline to the dominant ones that 

 they will produce a much higher grade of wood. Trees grown in 

 dense stands are usually free from lateral branches for a consider- 

 able distance from the ground and as a consequence the logs cut from 

 them will be relatively free from knots; while trees grown in open 

 stands or in open situations bear crowns which often reach almost to 

 the ground and produce numerous knots. Such trees as the latter, 

 consequently, yield an inferior grade of wood. 



In developing forests the owner or forester in charge should aim 

 to maintain a proper number of trees per acre and to treat them 

 so that they will not only yield a large quantity but also a good 

 quality of wood. He should not aim to differ from nature's ways 

 of doing things but improve on them. In order to improve the for- 

 est it is necessary that the forester carry on certain operations in 

 the immature stand which aim to improve the composition of the 

 stand and the form of the individual trees. He should also aim to 

 increase the rate of growth of the individual trees and as a result 

 increase the yield in volume and value of the final product. The 

 principal operations which one must carry out in order to realize 

 the above objects are: Cleanings, Liberation Cuttings, Thinnings, 

 Damage Cuttings, Pruning, Weeding, and Underplanting. 



Cleanings are cutting operations in young rather even-aged stands 

 which remove undesirable trees with little prospective value, and 



