WHAT FORESTRY IS AND WHAT IT DOES 191 



large open gaps where there is little chance for new trees 

 to spring up from seed furnished by the neighboring trees. 

 It is a method extensively practiced abroad where some of 

 the finest forests are the result. The U. S. government, as 

 well as many of the States, maintain forest-tree nurseries 

 where millions of little trees are grown from seed and 

 planted out on the National and State forests. Fig. 129 

 shows men engaged in this work. The fundamental prin- 

 ciples of starting and maintaining a nursery have already 

 been referred to in the chapter on " What Trees to Plant 

 and How." 



The third method of establishing a forest from seed is 

 by cutting the trees in the existing forest so that the seed 

 falling from the remaining trees will, with the addition 

 of light and space, readily take root and fill in the gaps 

 with a vigorous growth of trees, without artificial seeding 

 or planting. This gives rise to several methods of cutting 

 or harvesting forests for the purpose of encouraging natural 

 reproduction. The cutting may extend to single trees 

 over the whole area or over only a part of the whole area. 

 Where the cutting is confined to single trees, the system is 

 known as the " Selection System," because the trees are 

 selected individually, with a view to retaining the best 

 and most vigorous stock and removing the overcrowding 

 specimens and those that are fully mature or infested with 

 disease or insects. 



Fig. 130 is a diagrammatic illustration of the operation 

 of this system. In another system the cutting is done in 

 groups, or in strips, and the number of areas of the groups 

 or strips is extended from time to time until the whole 

 forest is cleared. This system is illustrated in Fig. 131. 

 Still another method consists in encouraging trees which 

 will thrive in the shade, such as the beech, spruce and 



